Development of Enantioselective Synthesis of Allenes Using Chirality Transfer from a Chiral Carbanion

2016 Fiscal Year Final Research Report

• Project/Area Number: 15K14929
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Chemical pharmacy
• Research Institution: Hiroshima University
• Principal Investigator: Takeda Kei 広島大学, 医歯薬保健学研究院(薬), 教授 (30135032)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: 不斉反応 / アレン / シアニドイオン / キラルカルバニオン / 相間移動触媒

Outline of Final Research Achievements

Reactions of γ-bromo-α,β,γ,δ-unsaturated acylsilanes with KCN and quaternary ammonium bromide derived from cinchona alkaloids afforded nonracemic 2-cyano-2-siloxyvinylallenes via a tandem process that involves a nucleophilic attack of a cyanide ion and a Brook rearrangement-induced conjugate vinylic 1,4-elimination. Based on this result and on the stereochemical outcome of the reaction using hydride ion as a chiral source, we propose a reaction pathway in which a Brook rearrangement-mediated vinylic conjugate 1,4-elimination occurs in a syn alignment between the C-Br bond and C-Si bond in the silicate intermediate. The finding that reactions using a chiral cyanide ion source provided nonracemic allene derivatives opens a new perspective in the enantioselective synthesis of highly functionalized allene derivatives.

Free Research Field

有機合成化学