Application of the Brook Rearrangement in Tandem with Single Electron Transfer Oxidative and Radical Processes
作者:Mikhail K. Klychnikov、Radek Pohl、Ivana Císařová、Ullrich Jahn
DOI:10.1002/ejoc.202000126
日期:2020.5.22
Rearrangement and radical puzzle: Chiral epoxides, silylated acetamides, and stable radical TEMPO provide, with the help of ferrocenium hexafluorophosphate, dioxygenated carbonylcompounds, which serve as versatile radical cyclization precursors.
The general preparation of enantiopure monoacidside-chains of several esters of cephalotaxine is described. The strategy, similar to Weinreb's approach to the synthesis of deoxyharringtonine, used as key intermediate the chiral nonracemic epoxide 11a prepared from the commercially available monomethyl itaconate (8). The key step of the strategy was the ring-opening of the epoxide 11a by using different
The isolation and structure determination of eldanolide, the wing gland pheromone of the male African Sugar Cane Borer, Eldana saccharina (Wlk.) is described. The absolute configuration was determined as (3S, 4R) by comparison of the CD spectra of the natural pheromone with both synthetic enantiomers.
Boron fluoride promoted cleavage of acetals by organocopper reagents application to asymmetric synthesis
作者:J.F. Normant、A. Alexakis、A. Ghribi、P. Mangeney
DOI:10.1016/0040-4020(89)80078-x
日期:1989.1
BF3. Et2O, organocopper and cuprate reagents promote the substitution of one alkoxy group of an acetal. Under the same conditions, alkoxy tetrahydropyrans react selectively, by ring cleavage. Chiral cyclic acetals, having a C2 axis of symmetry are diastereoselectively cleaved. The method serves to synthesize chiral secondary alcohols, after the removal of the chiral auxiliary.
A preparation of N,N-bis(trimethylsilyl)allenamines
作者:Robert F. Cunico、Chia P. Kuan
DOI:10.1016/0022-328x(94)05068-m
日期:1995.2
elimination of 2-[N,N-bis(trimethylsilyl)amino]alkenyl (diethyl)phosphates affords 1-[N,N-bis(trimethylsilyl)amino]-1,2-alkadienes (“allenamines”). Conjugatively-substituted allenamines undergo further metalation under these eliminative conditions to form allenyl carbanions which may be trapped in situ by chlorotrimethylsilane to give 3-trimethylsilyl-or 3,3-bis(trimethylsilyl)-N,N-bis(trimethylsilyl)allenamines