Martin, Benjamin, Ganiek, Maximilian, Ivanova, Maria and Knochel, Paul (2018) Mild Homologation of Esters via Continuous Flow Chloroacetate Claisen Reactions. Angewandte Chemie. International edition, 57. pp. 1-6. ISSN 14337851

Abstract

The highly chemoselective chloromethylenation of functionalized esters using
(di)chloroacetic acid ((D)CA) and LiHMDS (HMDS = hexamethyldisilazide) in a
continuous flow setup is reported. Flow conditions enabled an efficient reaction of
the unstable acetate dianion intermediates, leading to unprecedented scalability
under mild reaction conditions and at an economic reagent stoichiometry (-10 °C,
< 1 min, 1.0-2.4 equiv. dianion). The clean reaction profile allows the use of the
unpurified crude products in various heterocycle syntheses. Additionally, a novel,
catalyst-free substitution of monochloro ketones with (hetero)aryl zinc enolates is
reported leading to valuable 1,4-diketones.

Item Type:	Article
Date Deposited:	13 Dec 2018 00:45
Last Modified:	13 Dec 2018 00:45
URI:	https://oak.novartis.com/id/eprint/37863