α-Diketones as acyl anion equivalents: a non-enzymatic thiamine-promoted route to aldehyde–ketone coupling in PEG400 as recyclable medium
作者:Olga Bortolini、Giancarlo Fantin、Marco Fogagnolo、Pier Paolo Giovannini、Valentina Venturi、Salvatore Pacifico、Alessandro Massi
DOI:10.1016/j.tet.2011.08.056
日期:2011.10
By mimicking the peculiar behavior of thiamine diphosphate-dependent acetylacetoin synthase, it has been demonstrated that thiamine hydrochloride 2a and its simple analogue thiazolium salt 2b are able to activate alpha-diketones as acyl anion equivalents in nucleophilic acylations, such as the homo-coupling of alpha-diketones and the hitherto unreported cross-coupling between a-diketones and alpha-ketoesters. These carboligation reactions were optimized under stoichiometric (2a) and catalytic conditions (2b) by using eco-friendly PEG400 as the reaction medium, thus allowing both solvent and thiazolium salt recycling. (C) 2011 Elsevier Ltd. All rights reserved.