Utilization of whole cell mediated deracemization in a chemoenzymatic synthesis of enantiomerically enriched polycyclic chromeno[4,3-b] pyrrolidines

Abstract

Various aryl and alkyl substituted optically pure propargyl alcohols were obtained with excellent ee (up to >99%) and isolated yields (up to 87%) by deracemization using whole cells of Candida parapsilosis ATCC 7330. The whole cells show substrate specificity towards alkyl substituted propargyl alcohols and a switch in the enantioselectivity has been observed from 'R' to 'S' upon increasing the chain length. For the first time, enantiopure (R)-4-(3-hydroxybut-1-ynyl)benzonitrile, (R)-4-(biphenyl-4-yl)but-3-yn-2-ol, (S)-ethyl 3-hydroxy-5-phenylpent-4-ynoate and (S)-4-phenylbut-3-yne-1,2-diol were obtained using this strategy. Optically pure propargyl alcohol thus obtained was used as a chiral starting material in the synthesis of enantiomerically enriched poly-substituted pyrrolidines and a pyrrole derivative successfully demonstrating a chemoenzymatic route.

Direct observation of redox reactions in Candida parapsilosis ATCC 7330 by Confocal microscopic studies

“…From the earlier reports 1 3 27 the asymmetric reduction of prochiral ketones using C. parapsilosis ATCC 7330 is well documented. Therefore, the substrate 1b was subjected to asymmetric reduction but it resulted in low conversion (<10%) to the product alcohol, a phenomenon seen for substrates with bulky groups including naphthyl group which show either less or no conversion to the product alcohols 4 38 39 .…”

Lipase-catalysed enantioselective kinetic resolution of rac-lipidic alkynylcarbinols and a C5 synthon thereof via a hydrolysis approach

“…As already mentioned, most of the previously reported lipase-mediated resolutions of LACs were performed via acetylation in organic solvent [11][12][13][14][16][17][18][19][20][21][22][23]. Our research group has recently reported the LMKR of rac-2-Ac via hydrolysis using MeCN (20% in aqueous buffer medium) as co-solvent [5].…”

“…Lipase-mediated kinetic resolution (LMKR) of some rac-LACs was also reported as alternative strategy for the production of enantiopure compounds [11][12][13][14][15][16][17][18][19][20][21][22][23] most of the examples involving acetylation approach in organic solvent [11][12][13][14][15][16][17][18][19][20][21][22]. Recently, the LMKR strategy via hydrolytic approach was used by our research group to resolve the rac-acetates of the LACs 2 and 3 (Fig.…”

Enantio- & chemo-selective preparation of enantiomerically enriched aliphatic nitro alcohols using Candida parapsilosis ATCC 7330

“…This observation is in consensus with a recent report from our lab which also highlighted the effect of steric factors on the ee of product alcohol under the conditions studied using this biocatalyst. 58 Table 1 Asymmetric reduction of 1-nitro-2-butanone 1a using C. parapsilosis ATCC 7330 using different cosolvents…”