Reactions of 5-Indolizyl Lithium Compounds with Some Bielectrophiles

Abstract

Indolizyl-5-lithium anions react with succinic and phtalic anhidrides giving 1,4-keto acids, with oxallyl chloride giving 1,2-diketone, and with ethyl pyruvate giving 1,2-hydroxyacid. However, with α-halocarbonyl compounds, they react in different ways, forming the products of selective bromination at C-5 (with α-bromo ketones and esters of α-bromo acids) and 5-chloroacetyl indolizines.

Phenacylation of 6-Methyl-Beta-Nitropyridin-2-Ones and Further Heterocyclization of Products

“…While the chemistry of indolizines has been widely investigated [1], the chemistry of 5-substituted indolizines (A, Scheme 1) remains very poor because there are only a few reliable ways for their synthesis. Thus, there are examples of electrophilic substitution of indolizines lithiated at C-5 [2][3][4] and S N H reaction of 8-nitroindolizines at this position [5]. The standard Tchitchibabin reaction requires interaction of 6-substituted 2-picolines and alpha-bromoketones; by steric reasons, however, this reaction is almost impossible for 5-X-indolizines.…”