Facile Alder-Ene Reactions of Silylallenes Involving an Allenic C(sp<sup>2</sup>)H Bond
作者:Venkata R. Sabbasani、Genping Huang、Yuanzhi Xia、Daesung Lee
DOI:10.1002/chem.201503243
日期:2015.11.23
involving the activation of an allenic C(sp2)H over an allylic C(sp3)Hbond is described. In this ene reaction, the presence of a silyl substituent was found to be critical for the observed reactivity and selectivity since the corresponding alkyl‐substituted allenes show different reaction profiles. Computational studies show that the origin of this unusualreactivity is the lower bond dissociation
Direct and Stereospecific Synthesis of Allenes via Reduction of Propargylic Alcohols with Cp<sub>2</sub>Zr(H)Cl
作者:Xiaotao Pu、Joseph M. Ready
DOI:10.1021/ja8035527
日期:2008.8.1
Allenes can be synthesized via the direct SN2' addition of hydride to propargylicalcohols. Previous examples of this approach, however, have involved harsh reaction conditions and have suffered from incomplete transfer of central chirality to axial chirality. Here we show that Cp2Zr(H)Cl can react with the zinc or magnesium alkoxides of propargylicalcohols to generate allenes in good yield and in
Nickel-Catalyzed Regio- and Stereoselective Double Carboxylation of Trimethylsilylallene under an Atmosphere of Carbon Dioxide and Its Application to the Synthesis of Chaetomellic Acid A Anhydride
In the presence of a nickel catalyst and excess amounts of DBU and Me2Zn, various 1-trimethylsilylallenes smoothly reacted with two equivalents of carbon dioxide at an ambient temperature and pressure in regio- and stereoselective manners to provide 1-trimethylsilylprop-1-ene-2,3-dioic acid derivatives. A short total synthesis of chaetomellic acid A anhydride was achieved using this method.
A highly regioselective reduction of propargylic acetates has been attained by using SmI2 and catalytic Pd(0) in the presence of 2,4-dimethyl-3-pentanol affording various types of allenes in high yields.
Scope and stereochemical course of the addition of (trimethylsilyl)allenes to ketones and aldehydes. A regiocontrolled synthesis of homopropargylic alcohols
作者:Rick L. Danheiser、David J. Carini、Carrie A. Kwasigroch