A Michael Equilibration Model To Control Site Selectivity in the Condensation toward Aminopyrazoles.

Org Lett

†Chemical Development, Boehringer Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road, P.O. Box 368, Ridgefield, Connecticut 06877-0368, United States.

Published: June 2015


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Article Abstract

A Michael equilibration model is presented to provide for site-selective pyrazole condensations between alkoxyacrylonitriles and hydrazines. Both pyrazole isomers were accessed with high selectivity by employment of kinetically or thermodynamically controlled conditions. Substrate scope and identification of Michael intermediates, as well as competitive pathways, support the presented mechanistic proposal. Sandmeyer derivatization provided site-selective access to fully substituted pyrazoles.

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http://dx.doi.org/10.1021/acs.orglett.5b01248DOI Listing

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