Synthesis of 5-substituted pyrrole-2-carboxaldehydes. Part I. Generation of formal 5-lithiopyrrole-2-carboxaldehyde equivalents by bromine-lithium exchange of 2- …

SL Berthiaume, BL Bray, P Hess, Y Liu…

Index: Berthiaume, Sylvie L.; Bray, Brian L.; Hess, Petr; Liu, Yanzhou; Maddox, Michael L.; et al. Canadian Journal of Chemistry, 1995 , vol. 73, # 5 p. 675 - 684

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Citation Number: 6

Abstract

The first known lithiated 1-azafulvene derivatives, eg, 8 and 13 a, were generated by a low- temperature bromine-lithium exchange procedure with tert-butyllithium. These lithio species show substantial stability at≤-90° C because, at these temperatures, the sterically demanding 6-diisopropylamino moiety, unlike the dimethylamino group, completely inhibits nucleophilic addition to C-6. At higher temperatures, the addition of tert-butyllithium to C-6 ...