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α‐Regioselective Aqueous Mukaiyama Aldol Reaction of 2‐(Trimethylsilyloxy)furan with Pyruvates
Author(s) -
Adamkiewicz Anna,
Woyciechowska Marta,
Mlynarski Jacek
Publication year - 2016
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201600258
Subject(s) - regioselectivity , chemistry , aldol reaction , furan , nucleophile , pyrrole , organic chemistry , catalysis
A procedure that enables access to α‐(hydroxyalkyl)butenolides from 2‐(trimethylsilyloxy)furan and keto esters with excellent regiocontrol is reported. Despite their synthetic significance, there is a general lack of catalytic methodology for the α‐regioselective Mukaiyama‐type aldol reaction of O ‐silylated dienolates. We demonstrate that the challenging competition between the α and γ positions of the nucleophilic dienolate can be controlled by the use of aqueous solvent. This phenomenon, which is observed for 2‐(trimethylsilyloxy)furan, can be further extended to the reaction of 2‐(trimethylsilyloxy)thiophene and, less efficiently, to 2‐(trimethylsilyloxy)pyrrole. Moreover, initial application of water‐compatible chiral zinc complexes composed of ( R , R )‐diphenylethylenediamine‐based ligands affords enantiomerically enriched α‐addition products in good yields (up to 72 %) and with good enantioselectivity (up to 55 % ee ).