Highly Enantioselective Synthesis of 伪,伪-Dialkylmalonates by Phase-Transfer Catalytic Desymmetrization

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• 作者：Suckchang Hong ; Jihye Lee ; Minsik Kim ; Yohan Park ; Cheonhyoung Park ; Mi-hyun Kim ; Sang-sup Jew ; Hyeung-geun Park
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：April 6, 2011
• 年：2011
• 卷：133
• 期：13
• 页码：4924-4929
• 全文大小：901K
• 年卷期：v.133,no.13(April 6, 2011)
• ISSN：1520-5126

文摘

A novel enantioselective synthetic method for the construction of a quaternary carbon center from malonates via phase-transfer catalytic (PTC) alkylation has been developed. The asymmetric 伪-alkylation of diphenylmethyl tert-butyl 伪-alkylmalonates with alkylating agents under phase-transfer catalysis conditions (aq 50% KOH, toluene, 0掳C) in the presence of (S,S)-3,4,5-trifluorophenyl-NAS bromide (8) as PTC catalyst afforded the corresponding 伪,伪-dialkylmalonates in high chemical (up to 99%) and optical yields (up to 97% ee) which could be readily converted to versatile chiral intermediates. Notably, the direct double 伪-alkylations of diphenylmethyl tert-butyl malonate also provided the corresponding 伪,伪-dialkylmalonates without loss of enantioselectivity. The synthetic potential of this method has been demonstrated by the preparation of 伪,伪-dialkylamino acid and oxindole systems.