Biooxidations of someN-arylpiperidines and related compounds usingBeauveria sulfurescens

摘要

J. CHEM. soc. PERKIN TRANS. I 1993 88 I Biooxidations of some N-Arylpiperidines and Related Compounds using Beauveria sulfurescens Nicholas Floyd,a Francois Munyemana,b Stanley M. Robertsb and Andrew J. WiIlettsa a Department of Biological Sciences, University of Exeter, Exeter, Devon EX4 4Q D Department of Chemistry, University of Exeter, Exeter, Devon EX4 400 Beauveria sulfurescens ATCC 7159 oxidized the N-arylamines 3,4, 7, 13, 18, 20, 22 at the 4-position with good selectivity and in 3666 yield. The oxidation of organic compounds at ostensibly non-activated positions using selected microorganisms is a powerful technique that has proved to be particularly useful for the introduction of additional functionality into certain structural types. For example the regio- and stereo-selective hydroxylation of steroids and alkaloids has been studied in some depth.However when other, often simpler, structural types are sub- jected to such a biotransformation the position of oxidation is almost invariable difficult to predict and only crude models of the oxidation process are a~ailable.~Beauueria sulfurescens ATCC 7 I59 is a microorganism that has gained popularity as an easy-to-use microbiological oxidant,rsquo; and we have set out to determine the rules governing the site(s) attacked by this organism for a wide range of substrates. In view of current interest in the area we report herein some initial investigations using some N-arylpiperidines and related compounds. As expected N-phenylpiperidine 1is oxidized to the phenol 2 (27 yield?) using B.sulfurescens ATCC 7159. However, substitution at the para-position in the aromatic unit with an electron-withdrawing group leads to oxidation in the hetero- cyclic ring. For example, the N-arylpiperidines 3and 4 form the hydroxylated derivatives 5 and 6 in 42 yield ? and 34 yield,t respectively. The products 5 and 6 were identified by com- parison with authentic samples and no other oxidation prod- ucts were isolated from these fermentations. The ketone 7 is a particularly good substrate in this biotransformation yielding the hydroxylated material ti7 in 66 isolated yield? (see Experimental section) which was considerably higher than in an equivalent recently reported biotransformation.8 In contrast, the 4lsquo;-ethyl compound 9 furnished only the primary alcohol 10 in 30 yield.It is noteworthy that compound 7is a vinylogous amide and it has been observed previously that amides are often good substrates in these types of biotran~formation.~In this connec- tion, it was of interest to find that the ketones 11 and 12 were recovered unchanged from the biotransformation. Altering the position of the substituent in the aromatic ring led to less efficient conversions. Thus, the ketone 13 produced the keto alcohol 14 (20) together with recovered starting material 56). The rneta-substituted compound 15 formed two alcohols 16 (25)? and 17(31).? The thiophene deriv- ative 18 produced the alcohol 19 (37)? as the sole oxidation product. Gratifyingly, when the aromatic moiety was kept constant and the heterocyclic portion of the molecule varied, the results obtained were largely in accord with expectations.For example, oxidation of the 4-methyl-N-arylpiperidine20 gave the tertiary alcohol 21 (55)t while the perhydroazepine 22 furnished the t Starting material (1amp;20) was recovered: the yields of product(s) are calculated on the amount of starting material consumed. 6 CH2CH20H Ac i Rrsquo;=R~=H 10 11 n=l 2 Rrsquo;=oH,$=H 12 n =2 3 Rrsquo; = N02, $= H 4 Rrsquo;=CN,R~=H 5 Rrsquo; = NO2, $= OH 6 Rlsquo; = CN, R2= OH 7 Rrsquo; =AC,FLH 8 Rrsquo; =Ac, $=OH 9 Rlsquo; = Et, R2= H 13 Rrsquo; = R3 = H, R2=Ac 14 Rrsquo; = H, R~= AC, R~= OH 15 R1=Ac,R2=R3=H 16 Rrsquo; = AC, R~= H. R~= OH 17 Rrsquo; = CH(OH)Me, f? = R3 = H li d$ 0 0 AC Ac Ac 18 R=H 20 R=H 22 R=H 24 19 R=OH 21 R=OH 23 R=OH alcohol 23(58).? The latter alcohol was optically active (cch7 -1 1.4 (CHCl,, c 0.37)) and, through formation of the Mosherrsquo;s ester and NMR spectroscopy, the compound was judged to be a 82: 18 mixture of enantiomers. The absolute configuration of the major enantiomer was not determined.The pyrrolidine derivative 24 was not transformed under our standard conditions. In summary, 4rsquo;-substituted N-arylpiperidines and related compounds are oxidized with excellent selectivity using B. sulfurescens ATCC 7159. In comparison, parallel experiments using Curvularia lunata NRRL 2380 gave less satisfactory results; for instance, the ketone 7afforded the alcohol 8 in just 20 yield on incubation with the latter organism.Experimental Conversion of the Ketone 7 into the Alcohol 8 with Beauveria sulfurescens.---The bioconversion medium comprised corn steep liquor (20 g dm ,) and glucose (10 g dm ,) in water adjusted to pH 4.85 with aqueous sodium hydroxide (1 mol dm-3). In a typical fermentation, the sterilized medium was inoculated with a 72 h-old vegetative culture and incubated with reciprocal shaking (28 OC, 200 rpm) in a 2 dm-3 conical flask filled with 1 dm-3 of medium. After 72 h of growth, an ethanolic solution of 4'-piperidinoacetophenone(100 mg cm 3, (10 w/v) was added to the culture (100 mg dm-3). After an additional 72 h period of incubation, the mycelium was filtered off and washed with water and the filtrate was continuously extracted (48 h) with methylene dichloride. The organic phase was dried (MgSO,) and concentrated under reduced pressure. The crude residue was analysed by TLC using ethyl acetate as eluent. Flash chromatography over silica gel (eluent ethyl acetate) gave the alcohol 8 (65 mg) as well as starting material (10 mg).Data for compound 8 were as follows: R, 0.37 (ethyl acetate); m.p. 124-126 "C (lit.,7 123-124 "C); v,,,/cm-'(CHC13) 3625 (OH), 3030, 3010, 2980, 1665 (GO), 1600, 1515, 1425, 1195, 1045, 780 and 665; 6,(250 MHz, CDCI,) 7.87 (2 H, d, J 9.8),6.89(2H,d,J9.8),3.94(1 H,tt,J9,4.5),3.8amp;3.68(2H,m), 3.20-3.06(2H,m),2.51 (3H,s),2.0amp;1.92(2H,m), 1.76(1 H,s, OH) and 1.72-1.56 (2 H, m); 6,(62.9 MHz, CDCI,) 196.58 (M),153.89, 130.52, 127.11, 113.47, 67.40, 45.19, 33.61 and 25.99. J.CHEM. SOC. PERKIN TRANS. i 1993 Acknowledgements We thank the SERC (Biotechnology Directorate) for post- doctoral Fellowships (N. F., F. M.) and the SERC Mass Spectroscopy service for accurate mass determinations. References 1 H. Iizuka and A. Naito Microbial Conversions of Steroids and Alkaloids, University of Tokyo Press and Springer-Verlag, Berlin, 1981, pp. 1-396. 2 H. L. Holland, The Alkaloids (ed. R. G. A. Rodrigo), Academic Press, London, vol. 18, 1981. 3 K. Kieslich, Microbial Transjormations of Non-Steroid Cyclic Compounds, Thieme, Stuttgart, 1976. 4 K. Faber, Biotransformation in Organic Chemistry, Springer-Verlag, Heidelberg, 1992, pp. 18amp;1 and references therein. 5 A. Archelas, J. D. Fourneron and R. Furstoss, Tetrahedron Lett., 1988, 29,6611;R. A. Johnson, M. E. Herr, H. C. Murray and L. M. Reineke, J. Am. Chem. SOC., 1971,93,4880. 6 B. Vigne, A. Archelas, J. D. Fourneron and R. Furstoss, Tetrahedron, 1986,42,2452. 7 E. C. Taylor and J. S. Skotnicki, Synthesis, 1981,606. 8 R. A. Johnson, M. E. Herr, H. C. Murray, C. G. Chichester and F. Han, J. Org. Chem., 1992,57,7209. 9 G. S. Fonken and R. A. Johnson, Chemical Oxidations with Microorganisms, Marcel Dekker, 1972; A. Archelas, J. D. Fourneron and R. Furstoss, J. Org. Chem., 1988,53, 1797; W. Carruthers, J. D. Prail, S. M. Roberts and A. J. Willetts, J. Chem. SOC.,Perkin Trans. I, 1990,2854. Paper 3/0 1038D Received 22nd February 1993 Accepted 3rd March 1993