Electrophilic Azido Selenenylation of Alkenes. A Simple Synthetic Route to Racemic Taxol Side Chain
摘要:
Simple alkenes react with PhSeOTf and NaN3 in MeCN to afford beta-phenylseleno azides as the result of a stereospecific trans addition. The regioselectivity of the process is determined by the structure of the alkene.
A simple and mild azido-phenylselenenylation of terminal alkenes, which proceeds with complete anti-Markovnikov regioselectivity, has been developed. This reaction occurs when the alkenes are treated with (diacetoxyiodo)benzene, sodium azide, and diphenyl diselenide in dichloromethane at room temperature. The observed regioselectivity can be explained by assuming that the addition process is initiated by azido radicals. This was further supported by the results obtained starting from 1,6-heptadiene and from beta-pinene. Under the same conditions, efficient azido-phenylselenenylation of symmetrical olefins, 3,4-dihydro-2H-pyran, methyl acrylate, and vinyl crotonate can also be effected.
Electrophilic Azido Selenenylation of Alkenes. A Simple Synthetic Route to Racemic Taxol Side Chain
Simple alkenes react with PhSeOTf and NaN3 in MeCN to afford beta-phenylseleno azides as the result of a stereospecific trans addition. The regioselectivity of the process is determined by the structure of the alkene.
Phenylselenium azide addition to alkenes. A new and stereospecific introduction of Se and N into organic molecules.
作者:Alfred Hassner、Ananda S. Amarasekara
DOI:10.1016/s0040-4039(00)95624-7
日期:——
The first examples of direct introduction of PhSe and N3 functions by addition to olefins are reported. The addition of PhSeN3 to simple alkenes, as well as to activated alkenes takes place in the absence of a catalyst. The reaction proceeds stereospecifically but not regiospecifically, apparently via a 3-membered selenonium ion intermediate.