Exploiting Synergistic Catalysis for an Ambient Temperature Photocycloaddition to Pyrazoles
作者:Christopher P. Lakeland、David W. Watson、Joseph P. A. Harrity
DOI:10.1002/chem.201904210
日期:2020.1.2
Sydnone-based cycloaddition reactions are a versatile platform for pyrazole synthesis, however they operate under harsh conditions (high temperature and long reaction times). Herein we report a strategy that addresses this limitation utilizing the synergistic combination of organocatalysis and visible-light photocatalysis. This new approach proceeds under ambient conditions and with excellent levels
Pyrazole Synthesis Using a Titanium-Catalyzed Multicomponent Coupling Reaction and Synthesis of Withasomnine
作者:Supriyo Majumder、Kevin R. Gipson、Richard J. Staples、Aaron L. Odom
DOI:10.1002/adsc.200900293
日期:2009.8
coupling of an alkyne, isonitrile, and amine can be used to generate tautomers of 1,3-diimines. These diimines produced in situ undergo cyclization with hydrazine and hydrazine derivatives in a one-pot procedure to provide pyrazoles. Seventeen examples of pyrazoles are provided using this one-pot, 4-component procedure from simple starting materials. The regioselectivity of the alkyne addition can be