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
Titanium catalyzed one-pot multicomponent coupling reactions for direct access to substituted pyrimidines
作者:Supriyo Majumder、Aaron L. Odom
DOI:10.1016/j.tet.2010.02.066
日期:2010.4
A titanium-catalyzed 3-component coupling reaction can be used to generate tautomers of 1,3-diimines. These diimines produced in situ undergo condensation with amidines in a one-pot procedure to provide substituted pyrimiclines. Seventeen examples of pyrimidines are provided using this one-pot, 4-component procedure from simple starting materials. In some cases, catalyst architecture can be tuned to control the regioselectivity of the alkyne addition. Finally, the regioselectivity of amidine addition to unsymmetrical 1,3-diimines is discussed. (C) 2010 Elsevier Ltd. All rights reserved.