The unprecedented radical β-elimination of vinylsulfoxides opens a new access to functionalized di- and trisubstituted allenes. The radical precursors are obtained in two steps from a carbonyl derivative and a vinylsulfoxide. The radical translocation trick can also be used to trigger the β-elimination of the sulfinyl radical.
Copper-Catalyzed Enantioselective Hydrosilylation of Allenes to Access Axially Chiral (Cyclohexylidene)ethyl Silanes
作者:Shu Li、Jian-Lin Xu、Yun-He Xu
DOI:10.1021/acs.orglett.2c02359
日期:2022.8.19
A novel strategy of copper-catalyzed regio- and enantioselective hydrosilylation of 4-substituted vinylidenecyclohexanes with silanes was developed. In this protocol, various allenes and silanes were used to afford the corresponding (cyclohexylidene)ethyl silanes in moderate to high yields with good enantioselectivities.
A Convenient Terminal Allene Synthesis from Propargylic Acetates
作者:Michael H. Nantz、Daniel M. Bender、S. Janaki
DOI:10.1055/s-1993-25909
日期:——
The use of lithium butyl(phenylthio)cuprate as a reactant with propargylic acetates for the synthesis of terminal allenes is reported. Treatment of propargylic acetates with lithium butyl(phenylthio)cuprate in diethyl ether at - 78°C yields the title compounds on workup with aqueous ammonium chloride.
作者:John D. Spence、Justin K. Wyatt、Daniel M. Bender、David K. Moss、Michael H. Nantz
DOI:10.1021/jo960276i
日期:1996.1.1
A study of alkali metal amide-mediated isomerizations of terminal allenes is described. The isomerizations of substituted ethenylidenecyclohexanes to form diastereomeric mixtures of terminal alkynes have been conducted to determine factors which may influence the stereochemistry at the newly formed propargylic centers. An initial base screen revealed that potassium N-methylbutylamide (KMBA) exhibits the highest level of equatorial to axial alkyne diastereoselectivity. With the severely hindered terminal allene 26, the use of potassium 3-aminopropylamide is required to effect isomerization. A general synthesis of deuterated terminal allenes has also been achieved, and a mechanistic study using d(2)-allenes 18a,b has revealed the involvement of a propargylic anion in the course of the KMBA-mediated isomerizations.