Reaction of 1-bromo-1,2-dienes with alkylcuprates as a regio- and stereo-selective route to acetylenic or allenic compounds
作者:Carmela Polizzi、Carla Consoloni、Luciano Lardicci、Anna Maria Caporusso
DOI:10.1016/0022-328x(91)80179-n
日期:1991.10
Alkylcuprates react with 1-bromo-1,2-dienes to give allenic and/or acetylenic products. The selectivity of the crosscoupling is markedly dependent on the nature of the copper reagent, which plays a prominent role in determining both the regio- and the stereo-chemistry. The preparative aspects of these copper-induced reactions are discussed and their possible mechanism discussed.
The synthesis of the highly reactive 1,4-unsymmetrically substituted butatrienes 12a-c is described. When employing a strict synthetic protocol, these alkatrienes react with lithium metal to 3,4-dilithio-1,2-butadienes 20a-c as stable intermediates. The structure of 20 is supported by IR and NMR spectroscopic evidence. The same dianionic intermediate can be prepared in one case by double deprotonation
Cycloaddition reactions of allenes with N-phenylmaleimide. A two-step, diradical-intermediate process
作者:Daniel J. Pasto、Peter F. Heid、Steven E. Warren
DOI:10.1021/ja00377a022
日期:1982.6
e process. The stereochemical features controlling the formation of the stereoisomeric diradical intermediates and their ring closures are discussed. In addition to the cycloaddition processes, competitive ene reactions occur to produce intermediate dienes, which react further to produce 1:2 adducts or nonreactive alkyne-containing 1:1adducts. These ene reactions also appear to proceed via diradical
Regio- and Stereoselective Synthesis of Multi-Alkylated Allylic Boronates through Three-Component Coupling Reactions between Allenes, Alkyl Halides, and a Diboron Reagent
作者:Yu Ozawa、Kohei Endo、Hajime Ito
DOI:10.1021/jacs.1c06538
日期:2021.9.1
valuable precursors for the rapid and stereoselective construction of densely substituted carbon skeletons. Herein, we report the first synthetic approach for differentially 2,3,3-trialkyl-substituted allylic boronates that contain a stereodefined tetrasubstituted alkene structure. Copper(I)-catalyzed regio- and stereoselectivethree-component coupling reactions between gem-dialkylallenes, alkyl halides
Thermal isomerisation of adducts derived from t-butylcyanoketen and allenes
作者:Howard A. Bampfield、Peter R. Brook
DOI:10.1039/c39740000172
日期:——
The intervention of a zwitterionic intermediate is proposed in the thermalisomerisations of the t-butyl-cyanoketen-methylated allene adducts (6) and (8), but not for adducts (1)–(4); evidence is given for the intervention of a similar intermediate in the cycloaddition of t-butylcyanoketen to 1-t-butyl-1-methylallene.