Generation of [1,n]-dipolar intermediates and their reactions

2015 Fiscal Year Final Research Report

• Project/Area Number: 25460015
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Chemical pharmacy
• Research Institution: Hiroshima University
• Principal Investigator: Sasaki Michiko 広島大学, 医歯薬保健学研究院(薬), 准教授 (30379888)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 有機合成 / 合成化学 / 三員環 / 1,n-双極子 / 環化反応

Outline of Final Research Achievements

With the aim of developing a method that allows the generation of [1,n]-dipolar intermediates, we focused on base-induced ring-opening reactions of 2-(p-tosylmethyl)cyclopanecarboxylate. When the cyclopropane derivative was treated with LiN(SiMe3)2 in the presence of alkylidenemalonate, a cyclopentenecarboxylate derivative, which lacks a tosyl and a methoxycarbonyl groups, was obtained in high yields. We propose a mechanism for a newly developed reaction that involves (1) a Michael addition of a 1,3-dipolar intermediate generated by a base-induced ring opening to the malonate, (2) the formation of a five-membered ring bearing a p-tosylmethylcarbanion moiety via an intramolecular Michael reaction of the generated malonate anion to an α,β-unsaturated sulfone moiety, (3) the formation a four-membered ring by intramolecular attack of the carbanion to an ester carbonyl group, and (4) the formation of cyclopentenecarboxylate by liberation of p-tosylacetate via a formal cycloreversion.

Free Research Field

有機合成化学