A convenient entry into the rhoeadan skeleton. Total synthesis of (±) <i>cis</i>-alpinigenine
作者:Ijaz Ahmad、Victor Snieckus
DOI:10.1139/v82-385
日期:1982.11.1
provides the aminolactone 9a which by diisobutylaluminumhydride reduction followed by polyphosphoric acid mediated cyclization gives the tetracyclic product 10a, thus constituting a convergent, short entry into the rhoeadan alkaloid skeleton. Chromium trioxide oxidation of 10a affords a low yield of the corresponding lactone 11a. A parallel series of reactions starting from 7,8-dimethoxy-4-bromoisochroman-3-one
The syntheticapproach to the protopine alkaloids is described. Efficient construction of the alkaloid models 16a and 16b was accomplished by the general synthetic method consisting of photo-oxygenative ring enlargement of tetrahydrobenzindenoazepines 13a and 13b by singlet oxygen and further elaboration of the resultant 10-membered amido-ketone products 14a and 14b.