Unexpected Ti-catalyzed formal intramolecular [4+4] cycloaddition of 1,1′-bi[(S∗,S∗)-6-(trimethylsilyl)cyclohepta-2,4-dien-1-yl]

Reductive disilylation (Li+Me3SiCl−THF) of 1,3,5-cycloheptatriene led to 1,1′-bi[(S∗,S∗)-6-(trimethylsilyl)cyclohepta-2,4-dien-1-yl] (2). In the presence of TiCl4 in dichloromethane, 2 gave rise to a spherical molecule 5 resulting from an intramolecular formal [4+4] supra–supra cycloaddition.