of phenylboronic acids with stericallyhindered 2-bromo phenyl acetates or bromo phenyl acetamides, followed by sequential bicyclization of biarylacetamides promoted by oxalyl chloride/Lewis acid. The reduction of 4,5-dioxoaporphines provides a chemoselective entry to aporphines, dehydroaporphines and 4-hydroxy-dehydroaporphines. A three-steps total synthesis for (±)-O,O′-dimethylapomorphine from readily
Reagent-Controlled Cyclization-Deprotection Reaction to Yield either Fluorenes or Benzochromenes
作者:Dan Killander、Olov Sterner
DOI:10.1002/ejoc.201402722
日期:2014.10
Compounds with benzochromene and fluorene structures are common in nature and society, and they can have potentially useful biological activities. In this paper, conditions for the selective preparation of either a benzochromene or a fluorene from the same starting material are described. The procedure uses a reagent-controlled cyclization-demethylation to give the benzochromene, or an intramolecular