Synthesis of Novel 2,3-Dihydroimidazo[2,1-b][1,3]oxazoles Through Intramolecular Nucleophilicipso-Substitution in 2-Alkylsulfonylimidazoles

Abstract

Readily available 2-(benzylsulfanyl)imidazoles 6, were studied as potential precursors toward the synthesis of novel diversely substituted 2,3-dihydroimidazo[2,1-b][1,3]oxazoles. Thus, the reaction between enolates derived from 6 and different electrophiles as well as the addition of Grignard reagents to the carbonyl group in 6 were explored. The formation of the fused imidazoxazoles 20 under mild conditions was successfully accomplished taking advantage of the key role played by the 2-alkylsulfonyl moiety in 19 as an efficient leaving group in intramolecular nucleophilic ipso-substitution reactions.