No abstract

Enyne 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 Eand Z-isomer of triaryl group containing all carbon tetrasubstituted olefins (8 a, 8 a' and 8 b) via Pd-catalyzed stereoselective decarboxylative arylation reaction.

Chemoselective O-alkylation of 1,3-diketones is a formidable synthetic challenge due to competing C-alkylation reaction. In this report, N-triftosylhydrazones derived from 2-bromo(hetero)arylaldehydes are utilized for the O-alkylation of cyclic 1,3-diketones under...