Tunable Construction of Multisubstituted 1,3-Dienes and Allenes
via a 1,4-Palladium Migration/Carbene Insertion Cascade.
J Org Chem 2022;
87:12019-12035. [PMID:
36053185 DOI:
10.1021/acs.joc.2c01019]
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Abstract
Efficient palladium-catalyzed vinylic C-H alkenylation and allenylation of gem-disubstituted ethylenes with N-tosylhydrazones of aryl alkyl and diaryl ketones were achieved to access trisubstituted 1,3-dienes and tetrasubstituted allenes, respectively. An aryl to vinyl 1,4-palladium migration/carbene insertion/β-hydride elimination sequence proceeded to switch the chemo- and regioselectivities to give structurally diverse products. Use of 2-FC6H4OH additive enables enhancement of the reaction efficiency through accelerating the key 1,4-palladium migration process.
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