Rearrangement ofS-methylbenzylsulfoniumS-alkylides in non-basic media

摘要

J. CHEM. SOC. PERKIN TRANS. I 1995 431 Rearrangement of S-Methylbenzylsulfonium S-Alkylides in Non- Basic Media Tohru Tanzawa, Miyuki Ichioka, Naohiro Shirai and Yoshiro Sato" Faculty of Pharmaceutical Sciences, Nag0 ya City University, Tanabe-dori, Mizuho-ku, Nagoya 467, Japan S-Methylbenzylsulfonium S-alkylides, prepared by fluoride ion-induced desilylation of S-methyl-S- l -(trimethylsilyl)alkyI (2.4-disubstituted benzy1)sulfonium salts 8 in dimethyl sulfoxide, rearranged exclusively to Sommelet-Hauser products without Contamination of Stevens products. Although the Stevens rearrangement is a typical route for the isomerization of nitrogen and sulfur ylides and it has been the subject of many reports,' few have dealt with benzylsulfonium ylides. Hayashi and Oda reported the formation of Sommelet- Hauser products in 3-56 yields on treatment of dimethyl- (substituted benzy1)sulfonium salts with sodium methoxide in methanol, but they failed to mention Stevens products. They also stated that in the reaction of dibenzylmethylsulfonium perchlorate with sodium hydroxide, the ratio of the Sommelet- Hauser to the Stevens rearrangement product was increased as the concentration of the base rose, but no experimental results were reported.We have reported from studies of ammonium ylides in non- basic media that benzylammonium N-alkylides 1 are initially isomerized to isotoluene derivatives 2 via a 2,3 sigmatropic migration pathway, and are then converted into the products of Sommelet-Hauser rearrangement 3 and/or Stevens rearrange- ment 4 (Scheme 1).The former 3 are predominantly formed when an R' group is an electron-releasing or a weak electron- withdrawing substituent (Hammett para-substituent constant, gp z 0.6) and R2 is a hydrogen. The latter 4 are produced when R' is a strong electron-withdrawing group (e.g. NO2) and/or R2 is an alkyl group. However, the ylides giving 4 as the main product in non-basic media are converted into 3 in the presence of a strong basic amine (e.g. DBU) via a proton- dissociation and -recombination path~ay.~ These results suggest that only Sommelet-Hauser products are formed in basic media. Because the chemical behaviours of benzylsulfonium and benzylammonium alkylides are similar,' the Stevens products from the sulfonium ylides might be formed in non-basic media, especially from 4-nitrobenzylsulfonium S-methylides and benzylsulfonium S-alkylides. We examined the fluoride ion-induced desilylation of S-methyl+ -(trimethyl-silyl)alkyl( substituted benzy1)sulfonium salts 8.t The starting salts 8 were prepared by one of the three routes shown in Scheme 2.The results are summarized in Table 1. Reaction of 8 with cesium fluoride in dimethyl sulfoxide$ (DMSO) gave only the corresponding Sommelet-Hauser product 12 after 24 h at room temperature, except for a (2-methyl-4-methoxybenzyl) analogue 8h (entry 13 in Table 2). We were somewhat surprised that no Stevens product 13 was detected in any reaction mixture. The yield of methyl 142-7 It has been reported that a sulfonium ylide which was produced by fluoride-induced desilylation of S-methyl-S-(trimethyIsilyl)methyl(2-methy1benzyl)sulfonium triflate 8c in dimethoxyethane (DME), changed to a I :2 mixture of 10c and 12c in 64 yield.and that 1Oc was converted into 12c on a silica gel column. We are unable to reproduce this interesting conversion, however. 4 The reactions in DMSO proceeded more quickly to give higher yields of the products than in dimethylformamide or 1.2-dimethoxyethane. Table 1 S-Methylamp; 1-(trimethylsilyl)alkyl (substituted benzy1)-sulfonium salts 8 Total R' RZ R3 X Route" yield () a H H H OTf A 88 b H H Me OTf B 85 c Me H H OTf A 42 d H Me H Br C 58 e H Br H Br C 88 f H Me0 H OTf A 58 g H Me0 Me OTf B 40 h Me Me0 H OTf A 56 i H NO, H Br C 41 j H NO, Me OTf B 30 Route A: 5-6-8; B: 7-6-8; C: 5-8.1 2 3 4 Scheme 1 methyl-5-nitropheny1)ethyl sulfide 12j was low at room temperature but improved when the reaction was carried out at 0 "C(entries 17 and 18). To examine the reaction path, the reactions of 8a, d, f were carried out at 10 "C and quenched after 0.5 h. No change of the product from 8a (entry 1) was observed, but the products from 8d, f changed to complex mixtures (entries 5 and 9). These results suggest that 2-methyl- or 2-methoxy-substituted 6-(methylthio)methyl-5-methylenecyclohexa-1,3-dienes lld, f (isotoluene derivatives), which were initially formed from the ylides 9d,f existed in the reaction mixtures after 0.5 h but were decomposed during the aqueous work-up.During this research, we noticed that polymethoxy-substi- tuted 6-(dimethylamino)methyl-5-methylenecyclohexa-l,3-di-enes (isotoluene derivatives), which were 2,3 sigmatropic migration products of (polymethoxy-substituted benzy1)-ammonium N-methylides, were stable at room temperature, but quickly hydrolysed during aqueous work-up to polymeth- oxytoluenes, dimethylamine, and formaldehyde. However, 432 I. CHEM.SOC. PERKIN TRANS. I 1995 Table 2 Reaction of S-methyl-S-(trimethylsilyl)methyl(substituted benzy1)sulfonium salts 8 with CsF in DMSO Reaction Total Product ratio" Entry 1 8a 10 0.5 A' 2 8a RT 24 A 3 8b RT 24 A 4 8c RT 24 A 5 8d 10 0.5 A' 6 8d 10 0.5 B' 7 8d RT 24 A 8 8e RT 24 A 9 8f 10 0.5 A' 10 8f 10 0.5 B' II 8f RT 24 A 12 Sg RT 72 A 13 8h RT 24 A 14 8h RT 24 B 15 8h RT 24 C 16 8i RT 24 A 17 8j 0 0.5 Ad 18 Sj RT 24 A ____~~~~~~ ~ ~ ~ Temp.Time yield ("C) (h) Conditionb () 10 I1 75 -0 83 -0 80 -0 74 15 0 Complex mixture 59 -10 81 -0 74 -0 Complex mixture 60 -92 75 -0 87 -0 Complex mixture 80 15 0 78 12 0 78 -0 64 -0 31 -0 12 100 100 100 85 90 100 100 8 100 100 85 88 100 100 100 'Determined from the proton ratios of 'H NMR spectra. Condition A: the reaction was quenched with water; B: quenched with 12 rnol dm-3 aqueous NaOH; C: the reaction was carried out in the presence of DBU (5 mol equiv.).'DMSO-THF (3 : 1) was used as the solvent. DMSO-THF (5 :3) was used as the solvent. a Scheme 2 Reagenrs and conditions: i, Me,SiCH,SLi, Et,O, -20 "C, overnight; ii, Bu'Li, THF, -66 "C, R2C,H,CH2X, room temp., 3 h or overnight; iii, Me,SiCH,SMe, acetone or acetonitrile, room temp., overnight; iv, MeOTf, benzene, 0 OC, or ether, -15 OC, overnight when the reaction was quenched with 12 mol dm-3 sodium hydroxide, the hydrolysis was suppressed and Sommelet-Hauser rearrangement products or isotoluene derivatives were isolable.6 When the reactions of 8d, f were carried out at 10 OC and worked up with 12 rnol dm-, aqueous sodium hydroxide, the products were mixtures of lld, f and 12d, f (entries 6 and 10).A similar treatment of 8h gave a mixture of 2-methoxy-6-methyl-5- methylene-6-(methylthio)methylcyclohexa-l,3-diene 10h and 12h (entry 14).The same result was obtained when the reaction of 8h was carried out in the presence of DBU and worked up with water (entry 15). These results support that methoxy- substituted isotoluenes lld, f, h exist in the reaction mixtures at room temperature but quickly react with water to form complex mixtures. It is still unclear what types of decomposition occur in water. Thus, no Stevens rearrangement product was formed in the isomerization of benzylsulfonium ylides. It is interesting but unclear why such difference exists between the chemical behaviour of the N-ylides and the S-ylides.Experimental All reactions were carried out in N, or Ar. DMSO was dried by distillation under reduced pressure from CaH,. Diethyl ether was distilled from Na benzophenone ketyl. CsF was dried over Pz05at 180 "C under reduced pressure. 'H NMR spectra were recorded at 270,400 or 500 MHz. All melting and boiling points are uncorrected. J-Values are given in Hz. 4-Methoxybenzyl (Trimethylsilyl)methyI Sulfide 6f.-A solution of (trimethylsily1)methanethiol (4.33 g, 34.0 mmol) in ether (100 cm3) was added at -20 OC to butyllithium (1.41 mol dm-3 in hexane; 23 cm3, 37.0 mmol) followed, after 2 h by 4- methoxybenzyl bromide (5.60 g, 35.7 mmol); stirring was then continued overnight at the same temperature.The reaction was quenched with water (100 cm3) and the mixture was extracted with ether (3 x 100 cm3). The combined extracts were washed with saturated brine, dried (MgSO,), concentrated, and distilled under reduced pressure to give the title compound 6f (5.77 g, 60), b.p. 12O0C/1.O mmHg (Found: C, 60.2; H, 8.2. C,,H,,OSSi requires C, 59.95; H, 8.4); v,,,(film)/cm-' 1174 (OMe), 1250 and 846 (CSi); 6,(270 MHz; CDCI,; Meamp;) 0.05 (9 H, s, SiMe,), 1.68 (2 H, s, CH2Si), 3.65 (2 H, s, CH,S), 3.80 (3H,s,OMe),6.84(2H,d,J8.6,Ph)and7.21(2H,d,J8.4,Ph). 4-Methoxybenzyl 1-(Trimethylsily1)ethyl Sulfide 6g.-A solution of benzothiazol-2-yl 1-(trimethylsilyl)ethyl sulfide ' 7 (5.35 g, 20.0 mmol) in THF (200 cm3) was added at -60 "C to teri-butyllithium (1.70 mol dm-3 in pentane; 11.7 cm3, 20.0 mmol) and the mixture stirred for 2 h.4-Methoxybenzyl chloride (2.7 cm3, 20.0 mmol) was then added to the mixture after which stirring was continued overnight at the same temperature, and then for 3 h at room temperature. The reaction was quenched with saturated aqueous NH,CI (100 cm3) and the mixture was extracted with ether (3 x 200 cm3). The combined extracts were washed with water and saturated brine, dried (MgSO,), concentrated, and distilled under reduced pressure. The distillate at 138-1 39 "C/4 mmHg was chromato- graphed on silica gel (hexane-trichloromethane, 4: 1) to give the title suljide 6g (2.14 g, 42) (Found: C, 61.2; H, 8.8. C13HZ2-OSSi requires C, 61.4; H, 8.7); v,,,(film)/cm-' 1250 and 837 (CSi); 6,(270 MHz; CDCI,; Meamp;) 0.02 (9 H, s, SiMe,), 1.28 (3 H, d, J 7.3, CMe), 1.82 (1 H, q, J 7.3, CHSi), 3.71 (2 H, s, J.CHEM. SOC. PERKIN TRANS. 1 1995 0 10 R*yJySMe 13 Scheme 3 Reagents and conditions: i, CsF,DMSO, 10deg;C or room temp., 0.5-24 h CH,S), 3.80(3 H, s, OMe), 6.84(2 H, d,J8.6, Ph)and 7.24(2 H, d, J 8.6, Ph). 4-Methoxy-2-methylbenzyl (Trimethylsify1)methyI Sulfide 6h.--In a manner similar to that described for 6f, (tri- methylsi1yl)methanethiol (3.132 g, 26.04 mmol), butyllithium (1.60 mol dm-, in hexane; 16.3 cm3, 26.1 mmol), and Cmethoxy- 2-methylbenzyl bromide * were treated to give the title suljide 6h (3.81 g, 58x1, b.p. 127 OC/0.7 mmHg (Found: C, 61.1; H, 8.6. C13H220SSi requires C, 61.4; H, 8.7); v,,,(film)/cm-' 1253 and 848 (C-Si); 6,(400 MHz; CDCI,; Me,) 0.05 (9 H, s, SiMe,), 1.69 (2 H, s, CH,Si), 2.37 (3 H, s, PhMe), 3.66 (2 H, s, CH,S), 3.78 (3 H, s, OMe), 6.67 (1 H, dd, J8.2, 2.8, Ph), 6.73 (1 H, d, J 2.8, Ph) and 7.09 (1 H, d, J8.2, Ph).4-Nitrophenyl 1-(Trimethylsily1)ethyI Sulfide 6j.-In a manner similar to that described for 6g, a solution of 7(5.35 g, 20.0 mmol) in THF (200 cm'), tert-butyllithium (1 1.7 cm3, 20.0 mmol), and 4-nitrobenzyl bromide (6.48 cm3, 30.0 mmol) was treated to give the title sulfide 6g (1.93 g, 36), b.p. 149 OCjO.9 mmHg (Kugelrohr) (Found: C, 53.3; H, 7.0; N, 5.1. C,,HI9NO,SSi requires C, 53.5; H, 7.1; N, 5.2); vmax(film)/ cm ' 1250 and 853 (C-Si); 6,(270 MHz; CDCI,; Me,Si) 0.03 (9 H, s, SiMe,), 1.29 (3 H, d, J 7.2, CMe), 1.78 (1 H, q, J 7.2, CHSi), 3.78 and 3.83 (2 H, AB q, J 13.6, CH,S), 7.48 (2 H, d, J 8.7, Ph) and 8.17 (2 H, d, J8.7, Ph).S-Methyl-S- 1-( trimethylsilyl)ethyibenzylsulfonium Tripate 8b.-A solution of 6b (4.42 g, 19.7 mmol) and methyl triflate (2.7 cm3, 23.64 mmol) in ether (44cm') was stirred at -15 "C overnight. The solvent was evaporated under reduced pressure and the residue was washed with ether to give the title salt 8b (7.29 g, 9573, m.p. 73-74OC (Found: C, 43.0; H, 5.85. C,,H,,F,O,S,Si requires C, 43.30; H, 6.0); vm,,(KBr)/cm-' * This compound was prepared from 3,4-dimethylanisole (3.43 g, 25.18 mmol) with NBS prior to use.' 433 1263 and 847 (C-Si). The presence of the diastereoisomers was observed on the 'H NMR spectrum but assignment was difficult (isomer-l/isomer-2, 5 :I); 6,(500 MHz; CDCI,; Me,); isomer-I: 0.21 (9 H, s, SiMe,), 1.54 (3 H, d, J 7.3, CMe), 2.71 (3 H, s, SMe), 2.94 (1 H, q, J 7.3, CHS), 4.70 and 4.76 (2 H, AB q, J 12.3, CH,S) and 7.37-7.41 (5 H, m, Ph); isomer-2: 0.25 (9 H, s, SiMe,), 1.58 (3 H, d, J7.4, CMe), 2.79 (3 H, s, SMe), 3.29 (1 H, q, J 7.4, CHS), 4.48 and 4.68 (2 H, AB q, J 12.8, CH,S) and 7.51-7.53 (5 H, m, Ph).S-Methyl-S-(trimethylsilyl)methyI(4-methylbenzyl)sulfon-ium Bromide 8d.-A solution of 4-methylbenzyl bromide 5d (2.56 g, 14.90 mmol) and methyl (trimethylsi1yl)methyl sulfide (1.47 g, 10.9 mmol) in acetone (15 cm3) was stirred overnight at room temperature.The solvent was evaporated under reduced pressure and the residue was washed with ether to give the title salt 8d (2.02 g, 58), m.p. 114-1 16 OC (Found: C, 48.7; H, 7.2. C,,H,,BrSSi requires C, 48.9; H, 7.3); v,,,(KBr)/cm-' 1251 and 854 (CSi); 6,(270 MHz; CDC1,; Meamp; 0.10 (9 H, s, SiMe,), 1.79 (2 H, s, CH,Si), 2.15 (3 H, s, SMe), 2.20 (3 H, s, CMe),4.98(2H,s,CH2S),7.15(2H,d,J8.3,Ph)and7.28(2H, d, J 8.3, Ph). S-Methyl-S-(trimethylsilyl)methyl(4-bromobenzyl)sulfon-ium Bromide amp;.--In the same way, a solution of 4-bromo- benzyl bromide 5e (2.50 g, 10.0 mmol) and methyl (trimethyl- sily1)methyl sulfide (1.38 g, 10.3 mmol) in acetonitrile (15 cm3) wastreated togivethetitlesalt8e(3.38g,88),m.p. 112-113deg;C (Found: C, 37.4; H, 5.2. C,,HzoBr,SSi requires C, 37.5; H, 5.2); v,,,(KBr)/cm-' 1251 and 854 (C-Si); 6,(270 MHz; CDCI,; Meamp;) 0.10 (9 H, s, SiMe,), 1.79 (2 H, s, CH,Si), 2.15 (3 H, s, SMe), 4.43 (2 H, s, CH,S), 7.27 (2 H, d, J8.6, Ph) and 7.47 (2 H, d, J 8.6, Ph).S-Methyl-S-(trimethylsilyl)methyl(4-methoxybenzyl)sul-fonium Triflate 8f.-A solution of 6f (3.24 g, 13.5 mmol) and methyl triflate (1.5 cm3, 13.3 mmol) in dry ether (15 cm3) was stirred overnight at -10 "C. The solvent was evaporated under reduced pressure and the residue was washed with ether to give the title salt 8f (5.24 g, 96), m.p. 65-67 OC (Found: C,41.4; H, 5.8. Cl4H2,F,O4SZSi requires C, 41.6; H, 5.7); v,,,(KBr)/ cm-' 1159 (OMe), 1263 and 852 (C-Si); 6,(270 MHz; CDCI,; Me,Si) 0.24 (9 H, s, SiMe,), 2.57 (2 H, s, CH,Si), 2.79 (3 H, s, SMe), 3.82 (3 H, s, OMe), 4.70 and 4.73 (2 H, AB q, J 12.8, CH,Si), 6.93 (2 H, d, J 8.4, Ph) and 7.40 (2 H, d, J 8.4, Ph).S-Methyl-S- 1 -(trimethylsilyl)ethyl(4-methoxybenzyl)sui-fonium Trzpate 8g.-A solution of 6g (2.11 g, 8.3 mmol) and methyl triflate (1.1 cm3, 9.9 mmol) in ether (13 cm3) was stirred overnight at -16deg;C. The solvent was evaporated and the residue washed with ether to give the title salt 8g (3.26 g, 9473, m.p. 8687deg;C (Found: C, 42.8; H, 6.0. C15H25F304S2Si requires C, 43.0; H, 6.0); v,,,(KBr)/cm-' 1254 and 849 (C-Si). The presence of diastereoisomers was observed on the 'H NMR spectrum but assignment was difficult (isomer- ljisomer-2, 5: 1); 6,(270 MHz; CDCI,; Me,Si); isomer-1: 0.23(9H,s,SiMe3), 1.53(3 H,d, J7.3,CMe),2.71 (3 H,s,SMe), 2.89(1 H, q, 57.3, CHS), 3.81 (3 H, s, OMe), 4.63 and 4.77 (2 H, AB q, J 12.5, CH2S), 6.91 (2 H, d, J8.6, Ph) and 7.42 (2 H, d, J 8.6,Ph);isomer-2:0.28(9H,s,SiMe3),1.59(3H,d,J7.3,CMe), 2.78 (3 H, s, SMe), 3.31 (1 H, q, 37.3, CHS), 3.82 (3 H, s, OMe), 4.48and4.69(2 H,ABq,J12.5,CH2S),6.89(2H,d,J8.3,Ph) and 7.43 (2 H, d, J 8.3, Ph).S-Methyl-S-(trimethylsilyi)methyl(4-methoxy-2-methyl-benzy1)sulfonium Trzjlate 8h.-A solution of 6h (1.63 g, 6.42 mmol) and methyl triflate (0.73 cm3, 6.45 mmol) in benzene (10 cm3) was stirred overnight at 0deg;C. The solvent was evaporated and the residue was recrystallized from ethyl acetate-ether to give the title salt 8h (2.59 g, 96), m.p.106- 107 "C (Found: C, 43.3; H, 5.9. CI5H2,F,O,S2Si requires C, 43.0; H, 6.0); vma,(KBr)/cm-' 1263 and 850 (C-Si); 6,(400 MHz; CDCl,; Me,Si) 0.25 (9 H, s, SiMe,), 2.39 (3 H, s, PhMe), 2.57 (1 H, d, J 13.7, CH,Si), 2.89 (1 H, d, J 13.7, CH,Si), 2.89 (3 H, s, SMe), 3.80 (3 H, s, OMe), 4.67 (1 H, d, J 12.6, CH2S), 4.80 (1 H, d, J 12.6, CH,S), 6.75 (1 H, d, J2.7, Ph), 6.77 (1 H, dd,J2.7,8.1,Phjand7.38(1H,d,J8.1,Ph). S-Methyl-S-(trimethylsilyl)methyl(4-nitrobenzyl)sulfonium Bromide 8i.--In a manner similar to that described for 8d, a solution of 4-nitrobenzyl bromide 5i (3.24 g, 15.0 mmol) and methyl (trimethylsily1)methyl sulfide (2.10 g, 15.6 mmol) in acetone (15 cm3) was treated to give the title salt 8i (2.02 g, 4173, m.p. 119-120deg;C (Found: C, 41.1; H, 5.6; N, 4.2.C12H,,BrN02SSi requires C, 41.1; H, 5.75; N, 4.0); v,,,(KBr)/cm-' 1249 and 854 (C-Si); 6,(270 MHz; CDCl,; Me,Si) 0.10 (9 H, s, SiMe,), 1.79 (2 H, s, CH,Si), 2.15 (3 H, s, SMe),4.51 (2H,s,CHzS),7.56(2H,d,J9.6,Phjand8.10(2H, d, J 9.6, Ph). S-Methyl-S-1-(trimethylsiiyl)ethyl(4-nitrobenzyl)sulfonium Trzyate 8j.-In a manner similar to that described for 8b, a solution of 6j (1.93 g, 7.14 mmol) and methyl triflate (0.97 cm3, 8.56 mmol) in ether (1 1 cm3) was treated to give the title salt 8j (2.54 g, 82), m.p. 81-82 "C (Found: C, 38.9; H, 5.1; N, 3.0. C14H22F3N05SZSirequires C, 38.8; H, 5.1; N, 3.2); v,,,(KBr)/cm-' 1262 and 855 (C-Si). The presence of dia- stereoisomers was observed on the 'H NMR spectrum but assignment was difficult (isomer-1 /isomer-2, 4 : 1); 6,(270 MHz; CDCI,; Me,Si); isomer-1: 0.24 (9 H, s, SiMe,), 1.59 (3 H, d,J6.9,CMe),2.78(3 H,s,SMe),2.95(1 H,q,J6.9,CHS),4.88 and4.99(2H,ABq,J12.9,CH2S),7.80(2H,d,J8.9,Ph)and 8.23(2H,d,J8.9,Ph);isomer-2:0.28(9H,s,SiMe3),1.61 (3H, d,J7.3,CMe), 2.89(3 H,s, SMe), 3.35(1 H,q,J7.3, CHS),4.69 and 4.99 (2 H, AB q, J 12.9, CH,Ph), 7.77 (2 H, d, J 8.9, Ph) and 8.26 (2 H, d, J 8.9, Ph). Reaction of S-Methyl-S-(trimethylsilyl)methylbenzylsul-fonium Iodide 8a with CsF.-The salt 8a (375 mg, 1.O mmol) was placed in a 20 cm3-flask equipped with a magnetic stirrer, a septum, and a test tube which was connected to the flask by a short piece of rubber tubing.CsF (0.76 g, 5 mmol) was placed in the test tube.After the apparatus had been dried under reduced pressure and flushed with N,, a mixture of DMSO-THF (3 : I; 4 cm') was introduced at 10 "C with a syringe followed by CsF added from the test tube. The mixture was stirred at 10 "C for 0.5 h and then poured into water (100 cm3) and extracted with ether (4 x 50 cm3). The combined extracts were dried (MgSO,), concentrated, and distilled under reduced pressure to give methyl 2-methylbenzyl sulfide5 12a (114 mg, 7573, b.p. 129 OC/1.5 mmHg (Kugelrohr). When the same reaction was carried out in DMSO (3 cm3) and quenched after 24 h at room temperature, 12a (126 mg, 83) was obtained. Reaction of 8b with CsF.-In a manner similar to that described above, a mixture of 8b (388 mg, I .O mmol) and CsF (0.76 g, 5 mmol) in DMSO (3 cm3) was stirred for 24 h at room temperature and worked up to give methyl 1-(2-rnethylphenyl)- ethyl sulfide 12b (133 mg, 80), b.p.120 "C/2 mmHg (Kugelrohr) (Found: C, 71.95; H, 8.5.C,,H,,S requires C, 72.2; H, 8.5); v,,,(film)/cm-' 2969, 2916, 1489 and 669; 6,(500 MHz; CDCI,; Me,Si) 1.58 (3 H, d, J 6.7, CMe), 1.94 (3 H, s, SMe),2.38 (3H, s, PhMe), 4.16(1 H,q,J6.7, CHS), 7.11-7.25 (3H,m,Ph)and7.44(1H,d,J7.3,Ph). J. CHEM. SOC. PERKIN TRANS. 1 1995 Reaction of S-MethyI-S-(trimethylsilyl)methyl(4-methyl-benzy1)suuonium Iodide' amp; with CsF.-In the same way, a mixture of the salt 8c (766 mg. 2.0 mmol) and CsF (1.52 g, 10.0 mmol) in DMSO (6 cm3) was stirred for 24 h at room temperature and then worked up.IH NMR spectroscopy of the residual oil indicated the presence of 6-methyl-5-methylene-6- (methylthio)methylcyclohexa-1,3-diene' 1Oc and methyl 1 -(2,3-dimethylphenyl)ethylsulfide 12c. The ratio was calculated on the basis of the proton ratios of the 'H NMR spectra (entry 4 in Table 2). The samples were isolated on a HPLC column (Waters p Bondasphere 5~ Silica-lOOA, I50 x 19 mm, hexane- dichloromethane, 3 : 1). Compound 1Oc; I,,,(ether)/nm 305 (log E 3.75); 6,(400 MHz;CDCI,;Me,Si) 1.22(3H,s,CMe),2.10(3H,s,SMe),2.55 and 2.68 (2 H,ABq, J12.6, CH,S), 5.10(1 H, d, J I.l,=CH,), 5.15 (1 H, s, =CH2), 5.71 (1 H, dd, J9.5, 1.1,4-H), 5.87 (1 H, m, 2-H), 5.99 (1 H, ddd, J9.5, 5.6, 1.1, 3-H) and 6.16 (1 H, d, 59.3, 1-H).Reaction of 8d with CsF.-In the same way, a mixture of the sulfonium salt 8d (320 mg, 1 .O mmol) and CsF (0.76 g, 5.0mmol) in DMSO-THF (3 : 1) (4 cm3) was stirred at 10 "C for 0.5 h and then quenched with water. TLC and 'H NMR spectra of the ethereal extract indicated that the products were composed of a complex mixture and were difficult to isolate (entry 5 in Table 2). The same reaction was carried out and quenched with 12 mol dm-, NaOH. The ethereal extract was dried and concentrated. 'H NMR spectra of the residue (98 mg, 59) indicated the presence of two isomers: 2-methyl-5-methylene-6-(methyl-thio)methylcyclohexa-1,3-diene 1 Id and methyl 2,Sdimethyl- benzyl sulfide 1M. Compound lld (not isolated); S,(400 MHz; CDCl,; Me,) 1.79 (3 H, s, CMe), 2.17 (3 H, s, SMe), 2.60 (2 H, s, CH,S), 3.07(1 H, m,CCH), 4.96(1 H, s,=CH,), 5.08 (1 H, d, J 1.0,=CH2), 5.72 (2 H, m, 1-H, 3-H) and 6.10 (1 H, d,J9.5,4-H).The same reaction was carried out at room temperature and quenched with water after 24 h. Distillation of the ethereal extract gave 126 (134 mg, 8l), b.p. 80 "C/2.5 mmHg (Kugelrohr), S,(400 MHz; CDCI,; Me,Si) 2.04 (3 H, s, SMe), 2.30(3H,s,PhMe),2.34(3H,s,PhMe),3.72(2H,s,CH2S),6.98 (2 H, m, Ph) and 7.05 (1 H, d, J7.5, Ph). Reaction of 8e with CsF.-In the same way, a mixture of 8e (320 mg, 1.O mmol) and CsF (0.76 g, 5.0 mmol) was treated in DMSO (3 cm3) to give 5-bromo-2-methylbenzyl methyl suijide 12e(171 mg, 7479, b.p. 124"C/1.5 mmHg(Kugelrohr)(Found: C, 47.0; H, 4.8.C9H,,BrS requires C, 46.8; H, 4.8); v,,,(film)/cm-l 2914, 1485, 1435 and 869; 6,(270 MHz; CDCI,; Me,Si) 2.03 (3 H, s, SMe), 2.32 (3 H, s, PhMe), 3.61 (2 H, s, CH2S), 7.03 (1 H, d, J7.9, Ph) and 7.28-7.32 (2 H, m, Ph). Renction of 8f with CsF.-In a manner similar to that describedfor 8d, a mixture of 8f (405 mg, 1.0 mmol) and CsF (0.76 g, 5.0 mmol) in DMSO-THF (3 :1, 3 cm3) was stirred at 10 "C for 0.5 h and worked up with water. The products were a complex mixture (entry 9). The same reaction was carried out and quenched with 12 mol dm-3 NaOH and extracted with ether. The extract was dried and concentrated. 'H NMR spectroscopy of the residue (109 mg, 60) showed the presence of 2-methoxy-5-methylene-6-(methylthio)methylcyclohexa-l,3-diene llf and 5-methoxy- 2-methylbenzyl methyl sulfide 12f.The ratio was determined from the proton ratios of 'H NMR spectra (entry 10). Compound llf (not isolated); 6,(400 MHz; CDCl,; Me4Si)2.04(3H,s,SMe),2.51-2.69(2H,m,CH,S),3.31(1H, m,CCH),3.57(3H,s,OMe),4.92(1H,dd,56.0,2.4,I-H),5.02 J. CHEM. SOC. PERKIN TRANS I 1995 (I H,s,=CH,), 5.12(1 H,s,=CH,), 5.72(1 H,d,J9.8,3-H)and 6.15 (I H, d, J 9.8,4-H). The same reaction was carried out in DMSO (3 cm3) at room temperature and quenched with water after 24 h (entry 11). Distillation of the ether extract gave 12f (136 mg, 75), b.p. 126 OC,;1.5 mmHg (Kugelrohr); 6,(270 MHz; CDCI,; Me,Si) 2.03 (3 H, s, SMe), 2.31 (3 H, s, PhMe), 3.63 (2 H, s, CH,S), 3.78 (3 H, s. OMe), 6.72 (2 H, m, Ph) and 7.06 (1 H, d, J7.5, Ph).Reuction of8g with CsF.-In the same way, a mixture of 8g (420 mg. 1.O mmol) and CsF (0.76 g, 5 mmol) in DMSO (3 cm3) was stirred for 72 h at room temperalure and worked up to give methyl 1-(2-methyl-5-methoxyphenyl)ethylsulfide 12g (170 mg, 87), b.p. 135 OCjl.5 mmHg (Kugelrohr) (Found: C, 67.0; H, 8.2. C, 1H160S requires C, 67.3; H, 8.2); v,,,(film)/cm~' 2967, 2917, 1456 and 1038; 6,(270 MHz; CDCI,; Me,Si) 1.55 435 stirred for 24 h at room temperature and worked up with water (100 cm3) to give methyl 2-methyl-5-nitrobenzyyl sulfide 12i (1 53 mg, 78), b.p. 120 OCjl.5 mmHg (Kugelrohr) (Found: C, 55.0; H,5.55;N,7.05.C,Hl,NO,SrequiresC,54.8;H,5.6;N,7.1); v,,,(film)/cm~' 2968, 2920, 1568, 1493 and 850; 6,(400 MHz; CDCI,; Me,) 2.05 (3 H, d, SMe), 2.49 (3 H, s, PhMe), 3.72(2H,s,CH2S),7.33(1H,d,J8.2,Ph)and8.05-8.15(2H, m, Ph).Reaction of8j with CsF.-In the same way, a mixture of 8j (435 mg, 1.O mmol) and CsF (0.76 g, 5 mmol) in DMSO-THF (5 :3, 4.8 cm3) was stirred at 0 OC for 0.5 h and then treated to give methyl 1-(2-methyl-5-ni~rophenyl)ethylsulfide 12j (1 35 mg, 64), b.p. 170 OCjO.9 mmHg (Kugelrohr) (Found: C, 56.7; H, 6.1; N, 6.9. C,,H1,NO2S requires C, 56.85; H, 6.2; N, 6.6); v,,,(film)/cm-' 2980, 2924, 1586 and 1053; S,(270 MHz; CDCI,; Me,Si) 1.62(3 H, d, 36.9, CMe), 1.96(3 H, s, SMe), 2.49 (3H,d,J6.9,CMej,1.94(3H,s,SMe),2.30(3H,s,PhMe),3.79 (3 H, s, PhMe), 4.16 (1 H, q,36.9, CHS), 7.30 (I H, d, J8.3, Ph), (3H,s,OMe),4.11(1H,q,J6.9,CHS),6.69(1H,dd,J8.3,2.6, Ph) and 7.02-7.09 (2 H, m.Ph). Reaction of8h with CsF.-In the same way, a mixture of the sulfonium salt 8h (420 mg, 1.O mmol) and CsF (0.76 g, 5.0 mmol) in DMSO (3 cm3) was stirred for 24 h at room temperature and then quenched with water. 'H NMR spectroscopy of the ethereal extract indicated that the products were a complex mixture. The same reaction was carried out and quenched with 12 mol dm-, NaOH. 'H NMR spectroscopy of the residual oil indicated the presence of 2-methoxy-6-methyl-5-methylene-6-(methylthio)methylcyclohexa-l,3-diene 10h and 5-methoxy- 2,3-dimethylbenzyl methyl sulfide 12h. The ratio was calculated on the basis of the proton ratios of 'H NMR spectra (entry 14). The samples were isolated on an HPLC column (Waters p Bondasphere 5p Silica-IOOA, 150 x 19 mm, hexanexther, 97 :3).Compound 10h (an undistillable oil); /l,,,(ether)/nm 310 (log c: 3.90); 6,(400 MHz; CDCI,; Me,) 1.25 (3 H, s, CMe), 2.10 (3 H, s, SMe), 2.57 and 2.66 (2 H, AB q. J 12.6, CH,S), 3.57 (3 H, s, OMe), 4.63 (1 H, s, I-H), 5.13 (1 H, s,=CH,), 5.16 (1 H, s. =CH,), 5.75 (1 H, d, 39.8, 3-H) and 6.18 (1 H, d, J 9.8, 4-H). Compound 12h; b.p. 150OC/1.5 mmHg (Kugelrohr) (Found: C, 67.0; H. 8.1. ClIH,,OS requires C, 67.3; H, 8.2); v,,,(film)jcm-' 2970, 2917, 1455 and 1038; 6,(400 MHz; CDCI,; Meamp;) 2.05 (3 H, s, SMe), 2.19 (3 H, s, PhMe), 2.27 (3 H, s, PhMe) 3.66(2 H, s, CH,S), 3.77(3 H, s, OMe), 6.60(1 H, d,J2.7,Ph)and6.64(1 H,d,J2.7,Ph). A mixture of 8h (420 mg, 1.0 mmol), CsF (0.76 g, 5.0 mmol) and DBU (0.76 g, 5.0 mmol) in DMSO (3 cm3) was stirred for 24 h at room temperature and then poured into water (100 cm3).The ethereal extract was dried (MgSO,), and concentrated under reduced pressure. 'H NMR spectroscopy of the residual oil showed the presence of 10h and 12h (entry 16). Renction of8i with OF.-In the same way, a mixture of 8i (351 mg, I .O mmol), CsF (0.76 g, 5 mmol) in DMSO (3 cm3) was 7.99 (I H, dd, J8.3,2.3, Ph)and 8.31 (I H, d, J2.3, Ph). Acknowledgements This work was supported by a Grant-in-Aid for Scientific Research (No. 06672105) provided by the Ministry of Education, Science and Culture, Japan. References 1 (a)A. W. Johnson, Ylid Chemistry, Academic Press, New York, 1966; (b) A.R. Lepley and A. G. Giumanini, Mechanisms of Molecular Migralions,ed. B. S. Thyagarajan, Wiley, New York, 1971, p. 297; (c) I. Zugravescu and M. Petrovanu, N-Ylid Chemisrry, McGraw-Hill, 1976; (d)B. M. Trost and L. S. Melvin, Jr., Sulfur Ylides, Academic Press, New York, 1975; (e) I. E. Marko, in Comprehensive Organic Synthesis, eds. B. M. Trost and I. Fleming, Pergamon Press, Oxford, 1991, vol. 3, p. 913. 2 Y. Hayashi and R. Oda, Tetrahedron Lett., 1968.5381. 3 (a)S. Okazaki, N. Shirai and Y. Sato, J. Org. Chem., 1990, 55, 334; (b) N. Shirai, Y. Watanabe and Y. Sato, J. Org. Chem., 1990, 55, 2767; (c) Y. Machida, N. Shirai and Y. Sato, Synthesis, 1991, 117; (d) T. Kitano, N. Shirai and Y. Sato, Synrhesis, 1991, 996; (e)T. Tanaka, N. Shirai and Y. Sato, Chem. Pharm. Bull., 1992,40, 518; (f)T. Kitano, N. Shirai and Y. Sato, Chem. Pharm. Bull., 1992, 40,768; (g) T. Usami, N.Shirai and Y. Sato, J. Org. Chem., 1992,57, 5419; (h)Y. Sato, N. Shirai, Y. Machida, E. Ito, T. Yasui, Y. Kurono and K. Hatano,J. Org. Chem., 1992,57,6712;(i)T. Kitano, N. Shirai, M. Motoi and Y. Sato, J. Chem. SOC.,Perkin Trans. I, 1992,2851. 4 T. Tanaka, N. Shirai, J. Sugimori and Y. Sato, J. Org. Chem., 1992,57, 5034. 5 A. Padwa and J. R. Gasdaska, Tetrahedron, 1988,44,4147. 6 Y. Maeda, N. Shirai, Y. Satoand H. Takewaki, J. Org. Chenr.,in press. 7 A. R. Katritzky, W. Kuzmierkiewicz and M. Aurrecoechea, J. Org. Chem., 1987,52,844. 8 E. Ghera, A. Plemenitas and Y. Ben-David, Synthesis, 1984, 504. 9 D. J. Paterson, J. Org. Chem., 1967,32, 17 17. Paper 4/05272B Received 30th August 1994 Accepted 26th October 1994