Preparation of Substituted Oxazoles by Ritter Reactions of α-Oxo Tosylates
作者:Mark Taylor、Ping-Shan Lai
DOI:10.1055/s-0029-1218682
日期:2010.5
The Lewis acid catalyzed Ritter reaction of α-oxo tosylates with nitriles forms the basis of an efficient synthesis of oxazoles. Oxazoles with various substituents can be readily prepared from inexpensive starting materials. heterocycles - cyclizations - nitriles - carbocations - oxazoles - Ritter reaction
Functionalized methyl cis-4-oxoalk-2-enoates 2 are synthesized in a one-pot procedure by singlet oxygen oxygenation of the corresponding 2-methoxyfurans 1 in methanol and reduction of the resulting hydroperoxides 4 and 5 by the sulfides 6 which are selectively oxidized into the sulfoxides 7. The synthetic method has a wide range of applicability and affords compounds 2 stereoselectively and in good yields; concomitantly the sulfoxides 7 are obtained in excellent yields.
The first nucleophilic aromatic substitution of suitably activated 2-methoxyfurans with Grignard reagents
作者:M.Rosaria Iesce、M.Liliana Graziano、Flavio Cermola、Stefania Montella、Lucrezia Di Gioia
DOI:10.1016/s0040-4039(03)01430-8
日期:2003.7
The reaction of 2-methoxyfuroates 1 with Grignardreagents 2 leads to tertiary alcohols or SNAr products depending on the position of the alkoxycarbonyl group. OMe-Displacement occurs only for 3-substituted derivatives. It takes place even for 3-acetyl-2-methoxyfuran while the presence of a further ester function at 4 position induces the formation of the sole 4-tertiary alcohol. The OMe-substitution