Masuda borylation-Suzuki coupling (MBSC) sequence of vinylhalides and its application in a one-pot synthesis of 3,4-biarylpyrazoles.

Boris O A Tasch, Lisa Bensch, Dragutin Antovic, Thomas J J Müller

Index: Org. Biomol. Chem. 11(36) , 6113-8, (2013)

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Abstract

The Masuda borylation-Suzuki coupling (MBSC) sequence was successfully extended to the challenging coupling of vinylhalides with various (hetero)arylhalides using sterically hindered phosphane ligands. Starting from (hetero)arylhalides and α-bromocinnamaldehyde, the sequentially Pd-catalyzed process selectively furnishes α,β-substituted cinnamaldehydes without affecting the reactivity of the Michael system. These intermediates were implemented as entries into a novel synthesis of 3,4-diaryl 1H-pyrazoles in the fashion of a three-step one-pot procedure consisting of a Masuda borylation-Suzuki coupling and subsequent Michael addition-cyclocondensation-elimination sequence.