Preparation and electrophilic trapping of 7-lithiated benzoxazoles generated via benzyne cyclization

RD Clark, JM Caroon

Index: Clark, Robin D.; Caroon, Joan M. Journal of Organic Chemistry, 1982 , vol. 47, # 14 p. 2804 - 2806

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Citation Number: 44

Abstract

Treatment of N-pivaloyl-m-fluoroaniline (1) with excess n-butyllithium (2.5 equiv) in tetrahydrofuran-hexane solution at-20" C smoothly generated the lithio species 4 (Scheme I). Addition of a variety of electrophiles gave the 7-substituted 2-tert-butylbenzoxazoles 7-10. The powerful activating effect of the m-fluoro group on the ortho lithiatiod is an important feature of the facile benzyne formation. Under the same reaction conditions, the ...