Exclusive alpha-coupling in the aldol reaction of unsaturated trimethylsilyl esters: an efficient and practical direct synthesis of unsaturated beta-hydroxy acids.
The lithium enolates of trimethylsilyl but-3-enoate and 3-methylbut-3-enoate reacted with aldehydes and saturated or aromatic ketones at -70 degrees C to give exclusively the alpha-condensation products in excellent yields. The unsaturated beta-hydroxy acids thus obtained were directly identified, and the usual conversion into their methyl esters with diazomethane was not necessary. Unsaturated ketones underwent Michael reaction through alpha-addition leading to the unsaturated 5-oxo acids.
Bellassoued
Moncef
M
Laboratoire de Synthèse Organométallique associé au CNRS, Université de Cergy-Pontoise, Bâtiment des Sciences de la Matière, 5 Mail Gay Lussac, Neuville sur Oise, 95031 Cergy-Pontoise Cedex France. moncef.bellassoued@chim.u-cergy.fr
Grugier
Jérôme
J
Lensen
Nathalie
N
Catheline
Audrey
A