Enzymatic Approach to Enantiomerically Pure 5-Alken-2,4-diols and 4-Hydroxy-5-alken-2-ones:  Application to the Synthesis of Chiral Synthons

Abstract

Enantiomerically pure 1,3-diols 1-3 were obtained by a chemoenzymatic approach (lipase PS from Burkholderia cepacia). These diols were converted into useful chiral synthons, which could be considered homologues of glyceraldehyde and glyceric acid acetonides. Applications of these synthons to the de novo synthesis of sugars and preparation of conagenin carboxylic moiety were shown. Hydroxy ketone 4 was chosen as a model system for another synthetic evolution: it was obtained in enantiomerically pure form by enzymatic resolution and converted into chiral tetrahydropyranes, such as the stereoisomers of the commercial fragrance Gyrane.

Baker's Yeast Reduction of β‐Hydroxy Ketones

“…syn ‐ and anti ‐( E )‐4‐Hydroxy‐3‐methyl‐6‐phenylhex‐5‐en‐2‐one ( rac ‐10): 23 This compound was obtained from cinnamaldehyde (16.5 g, 0.125 mol) and butan‐2‐one (9.0 g, 0.125 mol); a 0.5:1 mixture of syn ‐ and anti ‐ 10 was obtained (13.5 g, 53 %): 1 H NMR (400 MHz, CDCl 3 ): δ = 7.45–7.15 (m, aromatic H), 6.70–6.55 (m, Ph CH =), 6.20–6.10 (m, = CH –CH), 4.65 (ddd, J = 5.6, 3.8, 1.5 Hz, CH OH syn ), 4.38 (t, J = 7.4 Hz, CH OH anti . ), 2.90–2.65 (m, CH CH 3 ), 2.23 (s, CH 3 CO anti ), 2.22 (s, CH 3 CO syn ), 1.20 (d, J = 7.3 Hz, CH 3 CH syn ), 1.14 (d, J = 7.1 Hz, CH 3 CH anti ) ppm.…”

“…(2 S ,4 R , E )‐6‐Phenylhex‐5‐ene‐2,4‐diol [(+)‐ anti ‐12]: 23 1.83 g (18 %). [ α ] D = +39.7 ( c = 1.15, CHCl 3 ) {ref 23. [ α ] D = +40.5 ( c = 1.13, CHCl 3 ) for (2 S ,4 R )‐ anti ‐ 12 }.…”

“…(2 S ,3 R ,4 S , E )‐3‐Methyl‐6‐phenylhex‐5‐ene‐2,4‐diol [(+)‐ anti , syn ‐17]: 23 0.807 g (8 %). ee = 99 % (HPLC).…”

New Caffeoylquinic Acid Derivatives and Flavanone Glycoside from the Flowers of Chrysanthemum morifolium and Their Bioactivities

“…The relative configuration of 1 was determined by the coupling constant and ROESY data (Figure 2b). The J 7′′, 8′′ and J 8′′, 10′′ values of 10.0 Hz [25] together with the ROESY correlations from H-10′′ to H-7′′ and H-12′′ suggested that H-7′′, H-10′′, and H-12′′ are cis -orientated. Attempts to determine the absolute configuration of compound 1 were unsuccessful due to the insufficient amount of sample.…”

Synthesis of L‐ and D‐4,6‐Dideoxyhexoses and 4,6‐Dideoxy‐C‐phenylglycosides from Enzyme‐Generated Products

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) several stereogenic centres. We have recently optimized [11] an enzymatic method for the kinetic resolution of 1,3-diols of type I (Scheme 1), to be converted into chiral synthons II, showing two or three stereogenic centres with controlled stereochemistry and one carbonyl group suitable of further functionalisation. Scheme 1. We wish herein to report on the synthesis of the single stereoisomers of new 1,3-diols 1 with defined stereochemistry at three adjacent stereogenic centres and on their use as chiral synthons to prepare biologically active molecules such as 4,6-dideoxyhexoses 2 and 4,6-dideoxy-C-phenylglycosides 3, which contain non-oxygenated carbon atoms in positions 4 and 6 in the sugar ring.…”