Issue 2, 2000

1,3-Dipolar cycloaddition of azomethine ylides derived from imines and difluorocarbene to alkynes: a new active Pb-mediated approach to 2-fluoropyrrole derivatives

Abstract

Domino reactions of imines with difluorocarbene in the presence of electron-deficient alkynes lead to 2-fluoropyrrole derivatives. The process involves intermediate azomethine ylide formation, its 1,3-dipolar cycloaddition to alkyne, followed by dehydrofluorination. A modified difluorocarbene generation method using active lead for dibromodifluoromethane reduction is proposed, providing shorter reaction time and improved yields of fluoropyrroles. The reactions with monoactivated acetylenes occur regioselectively. The cycloaddition of ylides to dipolarophiles such as phenylpropynal, whose carbonyl group is more active than the triple bond, gives rise to oxazolidine derivatives, implying a change in the reaction site.

Article information

Article type
Paper
Submitted
08 Jul 1999
Accepted
28 Oct 1999
First published
27 Jan 2000

J. Chem. Soc., Perkin Trans. 1, 2000, 231-237

1,3-Dipolar cycloaddition of azomethine ylides derived from imines and difluorocarbene to alkynes: a new active Pb-mediated approach to 2-fluoropyrrole derivatives

M. S. Novikov, A. F. Khlebnikov, E. S. Sidorina and R. R. Kostikov, J. Chem. Soc., Perkin Trans. 1, 2000, 231 DOI: 10.1039/A905518E

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