1,3-bis(diarylmethylidene)-2-methylidenecyclohexanes in cycloaddition and cyclodimerization reactions. The role of stereoelectronic factors.

Abstract

Cycloaddition and cyclodimerization reactions of 1,3-dibenzylidene- and 1,3-bis(p-methoxybenzylidene)-2-methylidenecyclohexanes, i.e., the diaryltrienes with fixed S-cis-configurations of exocyclic double bonds are studied. These compounds undergo in situ cyclodimerization of the [4 + 2]-type upon dehydration of the precursor tertiary alcohols and form endo-adducts in the Diels-Alder reaction with N-phenylmaleimide. In the presence of CF3COOH, acid-catalyzed cyclodimerization takes place leading to methylidene-substituted spirocyclodimers, which undergo intramolecular cyclization upon prolonged contact with CF3COOH to form a fused carbocyclic system containing a central, 'three-petal' fragment of six-membered rings.

• Authors: Elena I Klimova, Marcos Martínez García, Tatiana Klimova, S Hernandez Ortega, Leon V Bakinovsky
• Journal: Organic & biomolecular chemistry (Org Biomol Chem) Vol. 1 Issue 7 Pg. 1210-5 (Apr 07 2003) ISSN: 1477-0520 [Print] England
• PMID: 12926397 (Publication Type: Journal Article)