Synthesis of Novel 2,3-Dihydroimidazo[2,1-b][1,3]oxazoles Through Intramolecular Nucleophilic ipso-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.

Key words

alkylsulfonyl groups - leaving groups - intramolecular nucleophilic ipso-substitution - imidazoles - 2,3-dihydroimidazo[2,1-b][1,3]oxazoles

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26

Crystallographic data (excluding structure factors) for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication No. CCDC-187224 (Compound 24). Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: [phone]; e-mail: [e-mail]).