Divergent Reactivity of α,α-Disubstituted Alkenyl Hydrazones: Bench Stable Cyclopropylcarbinyl Equivalents

Herein we report the divergent reactivity of 2,2-dialkyl-3-(E)-alkenyl N-tosylhydrazones using Pd-catalyzed cross-coupling conditions, which enable the Z-selective synthesis of 3-aryl-1,4-dienes and gem-dialkyl vinylcyclopropanes. We found that the dialkylbiaryl phosphine ligand SPhos was the optima...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2022-02, Vol.144 (5), p.2101-2106
Main Authors: Ritchie, Nina F. C, Zahara, Adam J, Wilkerson-Hill, Sidney M
Format: Article
Language:English
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Summary:Herein we report the divergent reactivity of 2,2-dialkyl-3-(E)-alkenyl N-tosylhydrazones using Pd-catalyzed cross-coupling conditions, which enable the Z-selective synthesis of 3-aryl-1,4-dienes and gem-dialkyl vinylcyclopropanes. We found that the dialkylbiaryl phosphine ligand SPhos was the optimal ligand for this transformation producing skipped dienes in up to 83% isolated yield. The ratio of skipped diene to vinylcyclopropane is dependent on both the structure of the α,α-disubstituted hydrazones and the aryl halide partner. Using sterically encumbered aryl bromides provided the trans-cyclopropane products selectively in up to 69% yield. The reaction is stereospecific and stereoselective and occurs alongside a competing 1,2-alkenyl group migration pathway.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.1c12881