Synthesis of antimetabolites of sucrose

摘要

J. CHEM. SOC. PERKIN TRANS. 1 1994 Synthesis of Antimetabolites of Sucrose Luigi Lay, Francesco Nicotra," Cristina Pangrazio, Luigi Panza and Giovanni Russo Dipartimento di Chimica Organica e lndustriale, Centro per lo Studio dele Sostanze Organiche Naturali del CNR, via Venezian 21,20133 Milano, Italy The C-disacc ha rides D-glycero-D-id0-D-lYXo-7.1 1 -an hydro- 6-deoxydodec-5-ulof ura nose- (5.2) 7a and D-glyCerO- D-id0 -D-/yXo-7,11 -an hydro- 1-0-benzyloxysuccinyl -6-deoxydodec- 5 -ulof uranose- (5,2) 7b. antimetabolites of sucrose, the second of which is provided with a succinyl group which allows its linkage to biopolymers, have been synthesized. Hydroxymercuriation of the easily available 3- (2',3',4',6'-tetra-O- benzyl-~-~-glucopyranosyi)prop-1 -ene 1 followed by iodode-mercuriation, oxidation, and treatment of the so obtained iodo ketone with triphenylphosphine afforded the stabilized ylide 3- (2',3',4',6'-tetra- 0-benzyl-a-D-glucopyranosyl)-2-oxopropylidene-triphenylphosphorane 2.Reaction of the ylide 2 with a properly protected D-glyceraldehyde 3 afforded the a,P-unsaturated ketone 4 with a 12-carbon-atom skeleton, the stereoselective osmylation of which, followed by deprotection, gave the C-disaccharide 7a. To obtain the succinylated C-disaccharide 7b. (S)-2-0- benzyl-3-0- (benzyloxysucciny1)glyceraldehyde 3b was employed, which was obtained by enzymic benzyloxysuccinylation of 2-0-benzylglycerol and subsequent oxidation. Antimetabolites of carbohydrates are molecules of great of the C12-skeleton of the C-disaccharide 7 from two fragments: interest; they can inhibit the biological processes in which the a C,-fragment 2, derived from the easily available 3-(2',3',4',6'- structurally related natural carbohydrates are involved, and can tetra-0-benzylg1ucopyranosyl)prop-1-ene 1 and the C,-frag- substitute for them in their recognition or regulation roles.ment of a properly protected D-glyceraldehyde 3. The An interesting modification which produces antimetabolites assemblage of the two fragments, the stereoselective hydroxyl- of carbohydrates is the substitution of the glycosidic oxygen ation4 of the E-double bound obtained in this linkage, and the with a methylene group, to afford the so-called C-glycosides. formation of the furanosidic cycle affords the synthetic target 7.3a gives rise Recently much synthetic effort has been directed towards the The use of 2,3-O-isopropylidene-~-glyceraldehyde synthesis of C-disaccharides as potential inhibitors of to the C-disaccharide 7a, while coupling of compound 2 with 2-3b affordsglycosidases and disaccharidases, and to studies on their O-benzyl-3-O-(benzyloxysuccinyl)-~-glyceraldehyde conformational preferences compared with those of the the C-disaccharide 7b, with a spacer for the haptenization of structurally related disaccharide. biopol ymers. The synthesis of C-disaccharides of non-reducing sugars, in The Wittig reagent 2 was synthesized as follows. The which the interglycosidic methylene group links the anomeric hydroxymercuriation of the alkene 1, effected with aq.centres of both sugars, is a difficult task. In fact the most obvious Hg(OAc), in acetone, afforded the hydroxymercurial8 in 97 synthetic scheme, which involves the attack of a one-carbon yield as a mixture of isomers. The iododemercuriation of the atom unit to the anomeric centre of the first sugar, and then the hydroxymercurial 8, effected with I2 in CH2C12, gave the linkage of the thus obtained intermediate with the second sugar, hydroxy iodide 9 which was then oxidized with pyridinium has serious limitations in terms of p-elimination side-reactions chlorochromate (PCC) to the iodo ketone 10 in 87 yield. The and incorrect stereochemical outcome of the reaction. For reverse sequence, oxidation and then iododemercuriation, is these reasons, Kishi2'*' and we2d projected the synthesis of impracticable as the oxidation of the hydroxymercurial 8 C-disaccharides related to sucrose following two different affords mainly the methyl ketone 11.Any attempt to obtain synthetic strategies, both of which required the ex now this iodo ketone 10 by different routes, such as treatment of construction of the fructose moiety. the alkene 1 with Ag2C03-12,5 failed. The conversion of the We now describe the improvement of our synthetic scheme, iodo ketone 10 into the Wittig reagent 2 requires strictly with the introduction of a spacer which protects the hydroxy controlled experimental conditions. Simple treatment of the group at the fructosidic end of the molecule so avoiding the iodo ketone 10 with PPh, in benzene afforded quantitatively interconversion of the furanosidic form into the corresponding the methyl ketone 11.The conversion requires the presence pyranosidic form. Moreover, the spacer allows the conjugation of Et3N, and must be effected in MeCN at room tempera- of the antimetabolite to a biopolymer; the thus obtained ture. The transformation of the thus obtained phosphonium glycoconjugate may act as immunogen when administered to salt into the ylide 2 was effected in situ by treatment of the animals, and stimulate the production of antibodies against the reaction mixture with NaHCO,, and the ylide was purified by non-metabolizable analogue of sucrose. These antibodies might silica gel chromatography.Following this protocol, the ylide 2 be able to recognize the sucrose molecule, and, if this is the was obtained in 57 yield together with 40 of the methyl case, they can be used inter alia as biosensors. ketone 11. A detailed account of our previous results, which have been Treatment of the ylide 2 with 2,3-O-isopropylidene-~-reported in a communication,2d is also given. glyceraldehyde 3a in MeCN afforded the a,unsaturated ketone 4a in 88 yield. The osmylation of the double bond of compound 4a, effected in aq. acetone at -30 "C following the Results and Discussion catalytic procedure, occurred with 60 diastereoselection to The synthetic strategy (Scheme 1) involves the construction afford the diol 5a, which was separated from the diastereo- 334 J.CHEM. SOC. PERKIN TRANS. 1 1994 n + wos:R -0 3a RR'= Is 3b R=Su,R'=Bn1 'PphI HioHO .OBnw26H Sa RR'= Is,W'=H 7 -/RO -5 Sb R=Su,R'=Bn,R''=H HHO O G 6 RR'= IS, R"= AC HO 7a R=H 7b R=SU Scheme 1 kOFi 4a RR'=Is 4b R=Su,R'=Bn Bn = CH2Ph Is = isopropylidene Su = COCH22C02Bn R OH 8 R=CHpHgCl 9 R=CHpI BFi BnO R 0 10 R=CHzI 11 R=Me isomer by acetylation and careful chromatography on silica gel. The deisopropylidenation of 5a or of its acetate 6 can afford four different hemiacetalic isomers in equilibrium, the desired one being the a-furanoside 13. Treatment of the diacetate 6 with freshly prepared FeC1,-silica gel, in the absence of solvents,6 afforded a single product as shown by TLC pexane-ethyl acetate (1 :1); R,0.303.However, isolation of the product by chromatography on Florisil gave rise to two additional isomers (R, 0.51 and 0.58), which when re-treated with FeC1,-silica gel were reconverted into the former compound (R, 0.30). The product with R,0.30, isolated by silica gel chromatography, was found to be the a-pyranoside 12, which allowed the easy determination of the stereochemistry of the previous osmylation. Compound 12 shows a 10.5 Hz axial-axial coupling constant between 3-H and 4-H, and a 3 Hz axial- equatorial coupling constant between 3-H and 2-H. Moreover, a 1.5 Hz long-range coupling constant between 4-H and the OH group at C-5 clearly indicates the a-anomeric configuration OAc OH BnO A 13 and the conformational rigidity of the molecule.The presence of a carbonyl group beta to the anomeric carbon, as in compounds 4, 5,6 and 10 in the synthetic scheme, could in principle cause epimerization to the more stable J3-isomer.' The 5 Hz axial- equatorial coupling constant observed in compound 12between the anomeric hydrogen (7-H) and the adjacent 8-H clearly indicates that no epimerization occurs in the process. The filtration of a-pyranoside 12 on Florisil converted it partly into the furanosidic forms, the a-furanose 13 being predominant. The a-anomeric configuration of compound 13 was attributed on the basis of the 1.5 Hz coupling constant between 3-H and 4-H.*Deprotection of the mixture of isomers 12 and 13 by treatment with K,CO, in EtOH and subsequent catalytic hydrogenation with Pd/C afforded the analogue of sucrose, compound 7a, which was crystallized from EtOH.Owing to the hemiketalic nature of the C-disaccharide 7a, a mixture of furanose and pyranose forms was present in equilibrium, as evidenced by 13C NMR spectroscopy which J. CHEM. soc. PERKIN TRANS. 1 1994 H+Z" OR 14 R=H 15 R= COCHC02Bn shows three signals for the interglycosidic carbon (C-6) (6, 33.46, 34.71 and 38.35), the one at highest field being predominant (60). The highest chemical shift of C-6 in the predominant form suggests that this carbon is cis-oriented with the y-oxygen (y-effect), as in the a-furanose structure. Tests of sweetness, effected on a 3 aqueous solution, indicate that compound 7a is not sweet. In this regard it must be noted that apart from the substitution of the interglycosidic oxygen with a methylene, compound 7a differs from sucrose in the absence of the C-1 atom of the furanosidic moiety in the natural sugar. Studies on the structural requirements for sweetness indicate that the oxygen linked to C- 1 of the fructose moiety, and its distance from the hydroxy group at C-2 of the glucose moiety, are responsible for the sweetness response. The presence of a succinyl ester in position 1 of the de- protected C-disaccharide, as in compound 7b,will prevent the formation of the pyranosidic form and will allow linkage to a biopolymer.The synthesis of the succinylated C-disaccharide 7b requires the chiral glyceraldehyde 3b, in which the 2-OH is benzylated and the 3-OH benzyloxysuccinylated so that, at the end of the synthetic procedure, a simple debenzylation by catalytic hydrogenation will afford the desired product.2-O-Benzyl-3-O-(benzyloxysuccinyl)-~-glyceraldehyde 3b was synthesized by taking advantage from the results of Wong," who showed that the lipase from Pseudomonas spp. stereoselectively acetylates the pro-S hydroxy group of 2-0- benzylglycerol 14. Following this procedure, but employing benzyl trifluoroethyl succinate as the activated ester, we synthesized (S)-2-O-benzyl- 1 -O-(benzyloxysuccinyl)glyceroll5 in 78 e.e. (determined by HPLC on optically active poly- acrylamide and by NMR spectroscopy with europium tris- (heptafluorobutyrylcamphorate) Eu(hfc), as shift reagent).The oxidation of the free hydroxy group of compound 15 was effected with dimethyl sulfoxide (DMS0)-Ac,O, and the crude aldehyde 3b was treated with the ylide 2 in MeCN at room temperature. The desired (E)-a$-unsaturated ketone 4b was obtained in 59 yield after careful chromatography which allows its separation from Z-isomer. In particular, the E:Z ratio in the crude reaction mixture was 8: 1, as shown by 'H NMR spectroscopy. We also observed that the product with the wrong (Z)stereochemistry reacts more slowly than the E-isomer in the subsequent reaction. The osmylation of the a,p- unsaturated ketone 4b, effected at -30 "C, requires 48 h for completion. If the reaction is stopped after 24 h, virtually exclusive formation of compound 5b,the product of osmylation of the E-isomer 4b, is observed.The stereoselection of the osmylation, investigated by NMR spectroscopy, was higher than 90 (d.e.). Catalytic hydrogenation of the C-disaccharide 5b afforded the desired succinylated analogue of sucrose, compound 7b, in an a: p ratio of 4.3 :1. The ratio of the two isomers was determined by 13C NMR spectroscopy. In the predominant, a-isomer, the signal of the interglycosidic carbon (C-6) is shifted to higher field (6, 39.11 uersus 41.18) according to the y-effect due to the cis-oriented oxygen on C-4. Moreover, the signal of the anomeric carbon of the predominant a-isomer is shifted to lower field (6, 118.18 versus 115.19), according with the observation that the anomeric carbon of an a-fructofuranoside resonates at lower fields than that of the p-isomer." The succinylated analogue of sucrose, compound 7b, when tested in 3 aqueous solution, was found not to be sweet.Work is in progress to evaluate the effect of these molecules on different a-glucosidases. Experimental Mass spectra were recorded on a VG 70-70 EQ spectrometer.'H NMR and '3C NMR spectra were recorded on Bruker AC 300, Varian XL 200 and Bruker WP80 spectrometers for solutions in CDC13, unless otherwise stated; the signals of the aromatic carbons in the 13C NMR spectra are not reported. JValues are given in Hz. ID Values were measured at 20 "C on a Perkin- Elmer 241 polarimeter, and are given in units of lo-' deg cm2 g-'.Column chromatography was performed with the flash procedure using Merck silica gel 60 (23WOO mesh). TLC was performed on Merck silica gel-60 F-254 plates, developed with hexane+thyl acetate in the ratio reported in parentheses, and visualized by spraying with a solution containing H2S04 (31 cm3), ammonium molybdate (21 g) and Ce(S0,)2 (1 g) in water (500 cm3) and then heating at 110 "C for 5 min. Usual work-up refers to dilution with an organic solvent (CH,Cl,), washing with water to neutrality (PH test paper), drying with Na,S04, and evaporation under reduced pressure. 2-Hydroxy-3-(2',3',4',6'-tetra-O-benzyl-a-~-glucopyranosyl)-propylmercury Chloride 8.-To a solution of compound 1 (17.24 g, 30.6 mmol) in a 1 :1mixture of acetone-water (600 cm3) was added Hg(OAc), (9.75 g, 30.6 mmol) and the mixture was stirred for 4 h (TLC, 6:4).A solution of NaCl (3.55 g, 61.2 mmol) in 1 mol dm--3 NaOH (30.6 cm3) was then added and the mixture was stirred for 45 min. Usual work-up afforded title compound 8 (24.2 g, 97, mixture of two isomers), which was crystallized from hexane. M.p. 93-95 "C; 6,(75.432 MHz) (for the major isomer): 37.29 (t, C-1), 40.86 (t, C-3), 68.53, 71.68, 72.60, 78.42, 79.87 and 82.51 (6 d), 69.70, 74.03, 74.14, 75.57 and 75.96 (5 t) (Found: C, 53.1; H, 5.1. C3,H4,C106Hg requires C, 54.3; H, 5.05). 1-lodo-3-(2',3',4',6'-tetra-0-benzyl-a-~-glucopyranosyl)pro-pan-2-01 9.-To a solution of compound 8 (22 g, 27 mmol) in dry CH2C12 (70 cm3) under dry N, was added I, (6.8 g, 27 mmol).After 4 h (TLC, 6 :4) 5 aq. Na2S,03 was added, and the mixture was stirred for 30 min. Usual work-up afforded title compound 9 (17.2 g, 90, mixture of two isomers). Oil; 6,(75.432 MHz) (for the major isomer): 15.22 (t, C-1), 32.14 (t, C-3), 68.91, 71.53, 72.46, 78.54, 79.97 and 82.69 (6 d), 69.64, 73.86, 74.13, 75.64 and 76.05 (5 t) (Found: C, 62.4; H, 5.6. C37H41106requires C, 62.7; H, 5.8). 1-Iodo-3-(2',3',4',6'-tetra-O-benzyl-a-~-glucopyranosyl)pro-pan-2-one 10.-To a stirred solution of the alcohol 9 (9.3 g, 13 mmol) in dry CH,Cl, (60 an3), under N,, was added PCC (4.3 g, 20 mmol). After 6 h (TLC, 7 :3) the mixture was filtered on silica gel and eluted with Et,O.Evaporation afforded crude ketone 10 (8.10 g of labile crude product, 87), which was crystallized from Et,O-hexane to afford pure title compound 10 (4.3 g). The mother liquor was submitted to chromatography (7 :3) to afford the pure salt 8 (1.42 g recovery). Compound 10 had m.p. 8142°C (from Et,O-hexane); CarlD+13.4 (c 1, CHC13); 6"(200 MHz) 2.94 (1 H, dd, J 14.5, 8, 1-Ha), 3.12 (1 H, dd, J14.5,6, 1-Hb),3.66(l H,d, JlO,3-Ha), 3.58-3.80(6H,m), 3.82(1 H,d, J10,3-Hb),4.484.96(9H,m)and7.35(20H,Ph); dc(20.115 MHz) 7.35 (t, C-1), 36.95 (t, C-3), 71.42, 72.82, 73.47,77.76 and 79.17 (5 d), 69.12,73.47,74.83,75.13 and 81.78 (5 t) and 199.89 (s, C-2) (Found: C, 62.75; H, 5.5. C37H39106 requires C, 62.9; H, 5.6).2-0xo-3-(2', 3',4',6'-tetra-0-benzyl-a-~-glucopyranosyl)pro-pylidenetriphenylphosphorane2.-A solution containing PPh3 (1.6 g, 6.1 mmol) and Et,N (0.1 1 cm', 1.1 mmol) in dry MeCN (60 cm3) was added, through a double-tipped needle, under N,, to a solution of ketone 10 (4.3 g, 6.1 mmol) in MeCN (10 cm3). After 20 h (TLC, 7: 3), the mixture was washed with 5 aq. NaHCO, and extracted with CH,Cl,. The organic phase was then dried (Na,S04) and evaporated. Chromatographic puri- fication (AcOEt) afforded title compound 2 (2.9 g, 57) and the methyl ketone 11(1.7 g, 40). Compound 2, m.p. 39-41 "C (from AcOEt); aD +43.5 (c 1, CHCl,); dc(75.432 MHz) 38.06 (dt, Jc,p 14.5), 53.68 (dd, Jc,p 107.9), 69.75, 72.99, 74.15, 75.66 and 76.04 (5 t), 72.21, 73.50, 78.88,80.61 and 83.15 (5 d) and 201.22 (s, CO); m/z(FAB) 841 (M') (Found: C, 78.4; H, 6.1.C,,H,,O,P requires C, 78.55; H, 6.35). Compound 11, oil; aD +15.3 (c 1, CHCl,); 6,(300 MHz) 2.18 (1 H, s, Me), 2.77 (1 H, dd, J 15.4, 8.3, 1-Ha), 2.89 (1 H, dd, J 15.4, 5.5, 1-Hb), 3.60-3.90 (6 H, m), 4.45-5.00 (9 H, OCH,Ph, 1'-H) and 7.35 (20 H, Ph); 6,(75.432 Hz) 31.28 (9, Me), 41.68 (d, C-1), 69.45, 74.1 1, 74.1 1, 75.69 and 76.1 1 (5 t), 71.54, 73.05, 78.36, 80.03 and 82.75 (5 d) and 206.76 (s, CO) (Found: C, 76.7; H, 7.2. C37H400, requires C, 76.5; H, 6.9). (E,S)-5,6-Isopropylidenedioxy-1-(2',3',4',6'-tetra-O-benzyl-a-~-glucopyranosyl)hex-3-en-2-one4a.-A solution of the ylide 2 (1.5 g, 1.8 mmol) in MeCN (15 cm3) was stirred for 2 h under dry N, with 2,3-O-isopropylidene-~-glyceraldehyde3a (2.5 g, 19 mmol).The solvent was then removed under reduced pressure and the residue, submitted to chromatography (7 :3), afforded title compound 4a (1.09 g, 88) as an oil, alD +51.5 (c 1, CHCl,); 6,(200 MHz) 1.39 (3 H, s, Me), 1.41 (3 H, s, Me), 2.84(1 H,dd, J16,8, 1-Ha), 3.00(1 H,dd, J16,5.5, 1-Hb), 3.50- 3.84(7 H, m), 4.11 (1 H, dd, J8,6.5), 4.40-4.93 (10 H, m), 6.31 (1 H, dd, J 16, 1.3, 3-H), 6.64 (1 H, dd, J 16, 5.5,4-H) and 7.35 (20 H, Ph); 6,(50.288 MHz) 25.74 (4,Me), 26.52 (4,Me), 37.98 (t, C-1), 68.77, 68.77, 70.78, 72.84, 73.33, 73.50, 74.99, 75.37, 77.70, 79.32, 82.13, 110.22 (s, 0-C-0), 130.07 (d, C-3), 142.79 (d, C-4) and 196.87 (s, CO) (Found: C, 74.55; H, 7.0.C4, requires C, 74.5; H, 7.0). D-glycero-D-ido-D-lyxo-7,11-Anhydr0-8,9,10,12-tetra-O-benzyl-6-deoxy -1,2-0-isopropylidenedodec-5-ulose5a.-To a solution of enone 4a (1.08 g, 1.56 mmol) and N-methyl- morpholine N-oxide (NMMNO) (424 mg, 3.14 mmol) in acetone-water (8 :1, 10 cm3), cooled at -30 "C, was added a mixture of Os04 in Bu'OH (20 mg, 0.07 mmol, in 4 cm3). The mixture was stirred overnight at -30 "C, and then 5 aq. Na2S,0, was added. After 10 min of stirring, usual work-up afforded title compound 5a and its diastereoisomer at C-3 and C-4 in an 8:2 ratio, determined by 13C NMR spectroscopy (990 mg, 88). Crude compound 5a was directly submitted to acetylation which allowed its separation from the isomer; 6,(20.115 MHz) (for the major isomer in the crude mixture): 25.20 (4,Me), 26.96 (9, Me), 35.44 (t, C-6), 66.89,69.30, 70.90, 72.39,72.64,73.31,73.61,74.86,75.23,75.49,77.79,78.69,78.89, 81.73,109.36 (s, 0-C-O) and 209.62 (s, CO) (Found: C, 70.8; H, 7.1.C43H50010 requires C, 71.05; H, 6.9). The minor isomer: dC 25.38 (s, Me), 26.55 (s, Me), 36.78 (t, C-6), 109.78 (s, 0-C-0) and 208.59 (s, CO). D-glycero-D-ido-D-lyxo-3,4-~i-O-acety~-7,11-anhydro-8,9,-10,12-tetra-O-benzyl-6-deoxy-1,2-O-isopropylidenedodec-5-u1-ose 6.-To a solution of crude compound 5a (440 mg, 0.60 mmol) in dry pyridine (2 cm3) was added Ac,O (0.2 cm3). After 3 h, usual work-up and careful chromatography (6 :4) afforded title compound 6 (373 mg, 95 calculated on pure 5a) as an oil, aD +51.8 (~0.7, CHCl3);6,(200 MHz) 1.31 (3 H, S, Me), 1.40 (3 H, s, Me), 1.96 (3 H, s, Ac), 2.17 (3 H, s, Ac), 2.95 (2 H, d, J J.CHEM. SOC. PERKIN TRANS. 1 1994 6.3, 6-H,), 3.60-3.80 (7 H, m), 3.82 (1 H, dd, J 8.6, 5.5, 9-H), 3.95(1H,dd,J8.6,6,8-H),4.17(1H,q,J6,7-H),4.40-4.92(8 H, OCH,Ph), 5.77 (1 H, d, J2.2, 4-H), 5.83 (I H, dd, J6.5, 2.2, 3-H) and 7.35 (20 H, Ph); 6,(75.432 MHz) 25.74 (9, Me), 27.11 (4,Me), 36.04 (t, C-6), 66.58 and 69.28 (t, C-1 and C- 12), 66.57, 69.26, 73.35, 73.68, 75.34 and 75.66 (6 t), 70.06, 70.93, 72.63, 74.19, 77.16, 77.67, 79.20 and 82.14 (8 d), 110.10 (s, 0-C-0), 170.01 (s, COO), 170.30 (s, COO) and 201.54 (s, C-5) (Found: C, 69.4; H, 6.4. C4,H54012 requires C, 69.6; H, 6.7). (~R)-D-g~ycero-~-ido-~-lyx0-3,~-Di-~-acety~-7,11-anhydro-8,9,10,12-tetra-O-benzyl-6-deoxydodec-5-ulopyranoside-(5,1) 12.-The diacetate 6 (200 mg, 0.25 mmol) and a sample (200 mg) of a powder obtained by stirring anhydrous FeCl, and silica gel (8:100, w/w),~ were mixed by addition of Et,O (5 cm3), stirring, and subsequent evaporation of the solvent.After 1 h in the absence of solvent, TLC (1:l) showed the disappearance of the starting material (R, 0.70) and the formation of a single product (R, 0.30). The powder was then poured onto a column of silica gel (5 g) and eluted with hexane- ethyl acetate (1 :1) to afford title disaccharide 12 (148 mg, 78) as an oil; 6,(200 MHz) 1.60 (1 H, OH), 1.76 (1 H, dd, J 15, 1.5, 6-Ha),2.07(3H, s,Ac), 2.11 (3H, s,Ac),2.20(1 H,dd, J15,11.5, 6-Hb), 3.43 (1 H, dd, J 8.5,7.7,10-H) ,3.55 (1 H, dd, J7.5,5,8-H), 3.56-3.75(4H, 1-and 12-H2),3.67(1 H, t, J7.5,9-H),3.91 (1 H, ddd, J8.5,5.5,4, 11-H),4.10(1 H,m,2-H),4.40(9H,0CH2Ph and 7-H), 4.95 (1 H, d, J 1.5,OH), 5.22(1 H, dd, J 10.5,1.5,4-H), 5.32 (1 H, dd, J 10.5,3,3-H) and 7.3 (20 H, Ph) (Found: C, 68.3; H, 6.6.C4,H,OO 12 requires C, 68.6; H, 6.5). (5S)-D-glycero-~-ido-~-lyxo-3,4-Di-O-acetyl-7,11-anhydro-8,9,10,12-tetra-O-benzyl-6-deoxydodec-5-ulofuranose-(5,2) 13.-Compound 6 (200 mg, 0.25 mmol) was treated with FeC1,- silica gel as described before. After 1 h, Et,O (20 cm3) was added, and the mixture was filtered on Florisil and evaporated. Chromatography (6:4) afforded inter alia isomers 12 (28 mg) and 13 (20 mg) (R, 0.58 in 1:l).Compound 13: oil, 6,(200 MHz) 2.07 (3 H, s, Ac), 2.11 (3 H, s, Ac), 2.35 (2 H, m, 6-H,), 3.58-3.82(10H),4.44(1 H,d, J12,OCHPh),4.47(1 H,d, Jll, OCHPh), 4.59 (1 H, d, J 11, OCHPh), 4.63 (1 H, m, 7-H), 4.64 (1 H, d, J 12, OCHPh), 4.65 (1 H, d, J 11, OCHPh), 4.70 (1 H, d, J 1.5, 4-H), 4.76 (1 H, d, J 11, OCHPh), 4.81 (1 H, d, J 11, OCHPh), 4.92 (1 H, d, J 11, OCHPh), 4.98 (1 H, t, J 1.5, 3-H) and 7.3 (20 H, Ph); 6,(50.288 MHz) 20.79 (Me), 20.88 (Me), 24.93 (C-6), 66.19,68.70,69.67,71.58,72.50,73.47,74.96,75.37, 77.77,78.95,79.33,80.33,81.19,82.13,107.16(C-5), 170.26(CO) and 170.57 (CO) (Found: C, 68.3; H, 6.8). D-glyCerO-D-idO-D-lyX0-7,ll-Anhydro-6-deoxydodec-5-ulose 7a.-The crude mixture from the deisopropylidenation of compound 6 (12, 13 and its p-isomer, see preparation of compound 13) (200 mg, 25 mmol) in 90 EtOH (5 cm3) was treated with K2C03 (350 mg).After 2.5 h, dilution with water, extraction with ethyl acetate, drying with Na,S04, and evaporation of the solvent afforded the crude deacetylated product, which was dissolved in MeOH (10 cm3) and submitted to catalytic hydrogenation with Pd/C (lo, 40 mg). After 3 h, filtration and evaporation of the solvent afforded title compound 7a (65 mg, 80) as a mixture of pyranosidic and furanosidic forms (A), (B) and (C), m.p. 75 "C (decomp.) (from EtOH); 6,(50.288 MHz; CD,OD) (A) 33.46 (C-6) and 101.68 (C-5); (B) 34.71 (C-6) and 104.83 (C-5);(C) 38.35 (C-6) and 117.70 (C-5) (Found: C, 44.35; H, 6.7.C,,H,2010 requires C, 44.2; H, 6.8). Crystallization from EtOH enriched the sample in the form A: 6, 33.46 (t, C-6), 63.80 (t), 66.09 (t), 71.91 (d), 72.20 (d), 72.99 (d), 73.38 (d), 74.29 (d), 74.50 (d), 75.80 (d), 75.96 (d) and 101.68 (s, C-5). J. CHEM. soc. PERKIN TRANS, 1 1994 Benzyl2,2,2- TriJluoroethyl Succinate.-A mixture of succinic anhydride (5 g, 50 mmol), toluene (250 cm3), Et,N (7 cm3,10 mmol) and benzyl alcohol (5 cm3, 50 mmol) was stirred for 24 h. Usual work-up and chromatography hexane-ethyl acetate- MeOH (65 : 20 : 5) afforded the monobenzyl succinate tri- ethylammonium salt (6.5 g, 64).A mixture of the monobenzyl succinate (6.5 g, 31 mmol) in dry CH,Cl, (120 cm3) was then treated overnight with 2,2,2-trifluoroethanol (6 cm3) and dicyclohexylcarbodiimide (13 g).Water was then added and the mixture was stirred for 1 h, filtered, and submitted to usual work-up. Chromatography (7 :3) of the crude product afforded benzyl 2,2,2-trifluoroethyl succinate (9.0 g, quant.) as an oil, 6,(80 MHz) 2.71 (4 H, s, CH,CO), 4.45 (2 H, q, J 8, OCH,CF,), 5.14 (2 H, s, OCH,Ph) and 7.35 (5 H, s, Ph) (Found: C, 53.6; H, 4.6. C,,H,,F,O, requires C, 53.8; H, 4.5). (S)-2-O-Benzyl-1 -0-(benzyloxysucciny1)glycerol15.-A sol-ution of 2-O-benzylglycerol 14 (728 mg, 4 mmol) and benzyl trifluoroethyl succinate (4.6 g) in CHCl, (12 cm3) was stirred for 40 h at room temperature with lipase from Pseudomonas sp. (EC 3.1.1.3, Fluka) (50 mg; 42 U mg-I).The enantiomeric excess of the reaction, determined by HPLC (6: 3) on an optically active polyacrylamide column (Chiraspher 5 pm, Merck), was 78. Filtration of the reaction mixture on Celite, evaporation, and chromatography (7:3) afforded title compound 15 (1.5 g, quant.) as an oil, aD -11 {c 1.2, CHC1,; aD -14 calculated for the pure (S)-isomer}, 6,(300 MHz) 2.20 (1 H, OH), 2.53 (4 H, s, CH,CO), 3.77 (3 H, m, 2-H and 3-H,), 4.24 (2 H, d, J 5, 1-Hz), 4.58 (1 H, d, J 12, OCHPh), 4.69 (1 H, d, J 12, OCHPh), 5.13 (2 H, s, CO,CH,Ph) and 7.35 (10 H, Ph). Addition of Eu(hfc), split the singlet at 6 5.13 into two signals in the ratio 89: 11, respectively, at 6 5.66 and 5.57; 6,(75.432 MHz) 29.70 (t, 2 x CHZCO), 62.46 (t, C-3), 63.81 (t, OCHZPh), 67.26 (t, C-l), 72.80 (t, PhCHzOCO), 77.66 (d, C-2), 172.28 (s, CO) and 172.87 (s, CO) (Found: C, 67.5; H, 6.7.C,,H,,O6 requires C, 67.7; H, 6.5). (E,S)-5-Benzyloxy-6-(benzylox~succinyloxy)-1-(2',3',4',6'-tetra-O-benz~vl-a-~-glucopyranosyl)hex-3-en-2-one4b.-Com-pound 15(1.5 g, 4 mmol) was treated under N, with DMSO (39 cm3, 40 mmol) and Ac,O (20 cm', 28 mmol). After 4 h (TLC, 6 :4), dilution with CH,Cl,, washing many times with water, drying with Na2S0,, and evaporation under reduced pressure (20 mmHg and then 0.1 mmHg) afforded the crude aldehyde 3b(1.1 g). Compound 3b was dissolved in dry MeCN (35 cm3) and added, under N,, to compound 2 (1.4 g, 1.7 mmol). After 4 days (TLC, 7 :3), evaporation and chromatography (8 :2) afforded pure title enone 4b (917 mg, 59) and its Z-isomer (51 mg, 3.3). Oilt a,, +42 (c 1, CHCl,); 6,(300 MHz) 2.62 (4 H, S, CHZCO), 2.84 (1 H, dd, J 15.5,8, 1-Ha), 3.01 (1 H, dd, J 15.5, 5, 1-Hb), 3.55-3.83 (6 H, m, 2'-, 3'-, 4'- and 5'-H and 6'-H2), 4.1 1 (3 H, m, 5-H and 6-H2), 4.354.95 (10 H, m, 5 x OCH,Ph), 4.79 (1 H, m, 1'-H), 5.10(2 H, s, CO,CH,Ph), 6.34(1 H, d, J 16,3-H), 6.62 (1 H, dd, J 16, 5,4-H) and 7.06-7.50 (30 H, Ph); 6,(75.432 MHz) 29.61 (t, 2 x CHZCO), 38.60 (t, C-1), 66.05,67.21,69.35, 72.17, 73.98, 74.13, 75.64 and 76.03 (8 t), 71.38, 73.10, 76.46, 78.24, 79.98 and 82.69 (6 d), 132.25 (d, C-3), 142.32 (d, C-4), 172.57(s, 2 x CO,) and 197.36 (s, CO) (Found: C, 74.4; H, 6.3.C57H6001, requires C, 74.3; H, 6.6). D-glycero-D-ido-D-lyxo-7,ll-Anhydro-2,8,9,lO712-penta-O-benzyl-1-0-(benzyloxysuccinyl)-6-deoxydodec-5-ulose 5b.-A solution of enone 4b (880 mg, 0.94 mmol) in acetone-water (1 5 cm3; 8: 1) was treated at -30 "C with NMMNO (255 mg, 1.9 mmol) and a solution (0.25 cm3) of OsO, in Bu'OH (5 mg cm-,).After 48 h, aq. Na,S,03 was added and the mixture was stirred 337 for 1 h. Usual work-up and chromatography (7 :3) afforded title compound 5b (793 mg, 87) as an oil, alD +32 (c 1.6, CHCl,); dH(300 MHz) 2.63 (4 H, s, CH,CO), 2.74 (1 H, d, J 8, OH),2.96(2H,d, J7,6-H2),3.45-3.80(8H,m),4.00(1H,brt, J 8, 3-H), 4.22 (1 H, dd, J 12,4, 1-Ha), 4.36 (1 H, br d, J6,4-H), 4.424.90 (12 H, OCH,Ph, l-Hb and 7-H), 5.08 (2 H, s, CO,CH,Ph) and 7.10-7.40 (30 H, Ph); 6,(75.432 MHz) 29.43 (t, 2 x CHZCO), 35.59(t,C-6),63.42,66.96,69.25,73.14,73.70, 73.82, 75.27 and 75.73 (8 t), 70.41, 71.34, 72.78, 77.20, 77.20, 78.06,79.29 and 82.18 (8 d), 172.48 (s, CO,), 172.79 (s, COz) and 210.04 (s, co) (Found: c, 71.9; H, 6.7.C,,H6,0,, requires c, 72.0; H, 6.5). D-g~ycero-D-ido-D-~yxo-7,~1-Anhydro-1-O-(benzy/oxysuccin-yl)-6-deoxydodec-5-ulofuranose-(5,2)7b. A solution of ketone 5b (319 mg, 0.33 mmol) in MeOH (12 cm3) was submitted to hydrogenation with Pd/C (32 mg). After 20 h, filtration on Celite and evaporation afforded title compound 7b (137 mg, 96) as a deliquescent solid, 6,(300 MHz; D,O; 5OOC) (for the major isomer): 2.56 (1 H, dd, J 15,7, 6-Ha), 2.81 (1 H, dd, J 15,6, 6-Hb), 3.06 (4 H, m, CH,CO), 3.70 (1 H, s, 4-H), 3.80 (1 H, t, J7.5,10-H), 3.88-4.20 (4 H, m, 9- and 11-H, and 12-H,), 4.28- 4.65 (4 H, m, 1-Ha, 2-, 3- and 8-H), 4.72 (1 H, br d, J 13, 1-Hb) and 5.07 (1 H, m, 7-H); 6,(75.432 MHz; D20) (for the major isomer): 31.99 and 32.10 (t, CH,CO), 39.11 (t, C-6), 63.73 (t, C-12),67.18(t,C-l),71.19(d,C-4),75.60(d,C-7),76.94(d,C-9), 79.46 (d, C-lo), 80.15 (d, C-11), 82.86 (d, C-8), 83.81 (d, C-2), 84.68 (d, C-3), 118.18 (s, C-5) and 177.79 and 180.23 (s, CO,).The minor isomer (4.3 :1 ratio) showed 6, 41.18 (t, C-6) and 115.19 (s, C-5). Acknowledgements We thank 'Progetto Finalizzato Chimica fine 11' and MURST for financial support. References 1 (a)D. Rouzaud and P. Sinay, J. Chem. Soc., Chem. Commun., 1983, 1353; (6) B.Aebischer, J. H. 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