Convenient Access to 2-Arylpyrroles from 2-Lithio-<i>N</i>,<i>N</i>-dibenzylcyclopropylamine and Nitriles
作者:Jan Szymoniak、Armin de Meijere、Chloé Tanguy、Philippe Bertus、Oleg Larionov
DOI:10.1055/s-2006-950410
日期:2006.9
N,N-Dibenzylaminocyclopropyl ketimines formed as intermediates upon treatment of 2-lithiated N,N-dibenzylcyclopropylamines with nitriles, being donor-acceptor-substituted cyclopropanes, immediately underwent ring-enlarging rearrangement and 1,2-elimination of dibenzylamine to produce 2-substituted pyrroles in good yields (14 examples, 55-80%).
Substituted pyrroles were prepared by a gold(I)-catalyzed acetylenic Schmidt reaction of homopropargyl azides. The reaction allows for regiospecific substitution at each position of the pyrrole ring under mild conditions. A mechanism in which azides serve as nucleophiles toward gold(I)-activated alkynes with subsequent gold(I)-aided expulsion of dinitrogen is proposed.