A nickel(0) catalyzed cycloaddition of alkynes and isocyanates that affords pyrimidine-diones
作者:Hung A. Duong、Janis Louie
DOI:10.1016/j.tet.2006.03.119
日期:2006.8
carbene catalyzedcycloaddition of one alkyne and two isocyanates that affords pyrimidine-dione is described. The key to the success of this protocol is the use of unsymmetrically substituted alkynes that favors the formation of pyrimidine-diones over pyridones. A variety of pyrimidine-diones were prepared. A one-pot cycloaddition and Stille coupling were reported for tributyl(1-propynyl)tin. Competition
Abstract 1,1-Bis(trimethylsilyl)-2-propyne, prepared from propargyltrimethylsilane, was reacted, in the presence of a Lewis acid, with electrophiles (aldehydes, acetals) to afford (E)-silylated conjugated enynes.
Cobalt-Catalyzed Hydrohydrazination of Dienes and Enynes: Access to Allylic and Propargylic Hydrazides
作者:Jérôme Waser、José C. González-Gómez、Hisanori Nambu、Pascal Huber、Erick M. Carreira
DOI:10.1021/ol0517473
日期:2005.9.1
The cobalt-catalyzed hydrohydrazination reaction of dienes and enynes is presented. Allylic and propargylic hydrazines were obtained in synthetically useful yields (allylic amines, 60-90%; propargylic arnines, 47-83%) and good chemo- and regioselectivity.
Dialkylaluminum Hydride-Promoted Cyclodimerization of Silylated 1,3-Enynes via Skeletal Rearrangement
The dialkylaluminum hydride-promoted reaction of 1-silylalk-3-en-1-ynes gave symmetrical 1,2,3,5-tetrasubstituted benzenes as single regiolsomers. The novel cyclodimerization via skeletal rearrangement can be rationalized by an unprecedented mechanism Involving sequential hydroalumination, alkene isomerization, carboalumination, carbon-carbon bond cleavage, and retro-hydroalumination.
Expedient Construction of Multiple Stereogenic Centers in an Acyclic System via the Addition of Aldehydes, Ketones, and Chiral Imines to an Enyne−Titanium Alkoxide Complex
作者:Takashi Hamada、Ryo Mizojiri、Hirokazu Urabe、Fumie Sato