Abstract

A whole spectrum of biocatalysts for asymmetric reduction of prochiral ketones is well known including the Daucus carota root. However, this type of reaction is still challenging when pro-chiral ketones present low level of asymmetry, like heterocyclic ketones. In this work, 4,5-dihydro-3(2H)-thiophenone (1), 2-methyltetrahydrofuran-3-one (2), N-Boc-3-pyrrolidinone (3), 1-Z-3-pyrrolidinone (4) and 1-benzyl-3-pyrrolidinone (5) were studied in order to obtain the respective enantioselective heterocyclic secondary alcohols. Except for 5, the corresponding alcohols were obtained in high values of conversion and with high selectivity. In order to circumvent the low isolated yield of the corresponding chiral alcohol from 2, we observed that the use of carrots in the absence of water is feasible. Addition of co-solvents was needed to the water-insoluble ketones 3 and 4. Comparatively, baker’s yeast was used for bio reductions of 1, 3 and 4. And in terms of conversion, selectivity and work-up, the use of carrots were a more efficient biocatalyst, as well as a viable method for obtaining 5-member heterocyclic secondary alcohols.

摘要

用于不对称还原前手性酮的全谱生物催化剂是众所周知的，包括胡萝卜根。然而，当前手性酮呈现低水平的不对称性时，这种类型的反应仍然具有挑战性，如杂环酮。在这项工作中，4,5-二氢-3(2H)-噻吩酮 ( 1 )、2-甲基四氢呋喃-3-酮 ( 2 )、N-Boc-3-吡咯烷酮 ( 3 )、1-Z-3-吡咯烷酮 ( 4 )和1-苄基-3-吡咯烷酮( 5 )被研究以获得各自的对映选择性杂环仲醇。除了5，相应的醇以高转化率和高选择性获得。为了避免从2 中分离出相应手性醇的低产率，我们观察到在没有水的情况下使用胡萝卜是可行的。需要向水不溶性酮3和4添加共溶剂。相比之下，用于生物减少面包酵母1，3和4。在转化率、选择性和后处理方面，使用胡萝卜是一种更有效的生物催化剂，也是获得 5 元杂环仲醇的可行方法。