Affiliation:
1. Department of Chemistry Institute of Science Banaras Hindu University Varanasi 221005 India
Abstract
AbstractEnyne diesters derived from biaryls and related substrates undergo intramolecular [2+2]‐cycloaddition and concomitant cyclo‐reversion when treated with 10 mol% In(OTf)3 in 1,2‐dichloroethane. This enyne metathesis type cycloisomerization reaction enables the synthesis of phenanthrene, benzophenanthrene, benzotetraphene and other polycyclic (hetero)aromatic compounds bearing a synthetically useful diethyl β‐(hetero)arylidene malonate moiety in a step‐ and atom‐economic manner. In(OTf)3‐catalyzed two independent intramolecular cycloisomerization on substrates 5 a and 5 b provides direct access to benzotetraphenes 6 a and 6 b containing bis(diethyl β‐phenylmethylene malonate) moiety. Tetrasubstituted vinylidene malonate 4 a, substiututed by two different aromatic groups, is stereoselectively converted into E‐ and Z‐isomer of triaryl group containing all carbon tetrasubstituted olefins (8 a, 8 a′ and 8 b) via Pd‐catalyzed stereoselective decarboxylative arylation reaction.