Enantioselective hydrolysis of five-membered-ring acetates catalysed by Pseudomonas fluorescens lipase

Abstract

The racemic acetates of five-membered-ring alcohols were successfully resolved into the optically active alcohols with high optical purities by Pseudornonas fluorescens lipase.

Photoisomers of avermectins

“…This was dissolved in 5 mL of MeOH-CH2Cl2 (8:2 mixture) and subjected to preparative HPLC in two portions. The fractions were checked by analytical HPLC and the appropriate ones combined and concentrated in vacuo to give 40 mg of 3a (see below), 335 mg of la, and 202 mg of 2a: HPLC (85:15 MeOH-H2G, 1.0 mL/min) iR 12.3,14.5 min (3, 97%); UV X^(MeOH) 243 nm (« 28700); MS, m/e 872 (M+); 400-MHz 7H NMR (CDC13) 6.43 (1 H, ddd, J = 15, 11, 2 Hz, C10H), 5.84 (1 H, d, J = 11 Hz, CgH), 5.78 (1 H, dd, J = 10, 2 Hz, C22H), 5.73 (1 H, dd, J = 15, 4 Hz, CUH), 5.70 (1 H, s, C7OH), 5.57 (1 H, dd, J = 10, 2 Hz, C23H), 5.40 (1 H, d, J = 3 Hz, CV.H), 5.25 (2 H, m, C1SH, C19H), 4.78 (1 H, d, J = 3 Hz, CrH), 4.59 and 4.52 (2 X 1 H, 2 brd, J = 14 Hz, C^Hj), 4.31 (1 H, m, C5H), 4.20 (1 H, d, J = 4 Hz, C13H), 4.03 (1 H, d, J = 6 Hz, C6H), 3.40 and 3.37 (2 X 3 H, 2 s, C3,-OCH3 and C3DCH3), 3.26 (1 H, m, C2H), 2.74 (1 H, br s, C12H), 1.86 (3 H, s, C4CH3).…”

Synthesis of Isopeptide Epoxide Peptidomimetics

“…In developing a strategy for the synthesis of target olefin isosteres of the γ-glutamyl dipeptide (e.g., 6 ), and the corresponding internal epoxide derivatives (e.g., 4) , the two important synthetic challenges in the molecules that need to be addressed are, (i) stereospecific generation of the chiral center which serves as a pseudo α -carbon in the C -terminal glutamic acid replacement, analogous to the 2 S or 2 R stereochemistry in the parent isopeptide, and (ii) selective formation of the E -olefin during synthesis of the olefinic dipeptide isostere. Stereospecific generation of either stereoisomer at C-1 of the cyclopent-2-ene derivative, 8 or ent - 8 , from ethyl 2-oxocyclopenane carboxylate, 9 , has been achieved via lipase-mediated ester hydrolysis13,19-21, or a dynamic kinetic resolution,22 respectively, (Scheme 1) leading ultimately to the “ l -Glu-γ- l -Glu” mimetic, 4 , and the “ l -Glu-γ- d -Glu” mimetic, 5 . The desired E -olefin is most consistently achieved by the Julia-Kocienski reaction through the olefination of an aldehyde (e.g., 7 ) 23,24.…”

Desymmetrisation of meso-diols mediated by non-enzymatic acyl transfer catalysts

“…also be readily accessed in 99% ee by kinetic resolution of its racemate with 50% w/w of Pseudomonas floreces lipase in 39% yield. 5 In terms of catalyst loadings, availability, performance and efficiency, diamine catalyst C13 may be preferred for the acylation of 23a (entry 10).…”

“…Enantioenriched secondary alcohols have been efficiently generated by the asymmetric reduction of ketones or by the use of lipases in enzymatic kinetic resolution processes. [1][2][3][4][5] This latter approach is usually limited to yield products in only one enantiomeric form and extensive enzyme screening is often required. Small molecule catalysts are alternatives for the kinetic resolution of secondary alcohols (KRSA) and for the enantioselective desymmetrisation of meso-diols (EDMD).…”