Synthesis of tricyclic ring systems: [2+2] ketene addition reaction for preparation of tricyclic ketone, alcohol, and lactone derivatives

Abstract

The addition of dichloroketene to 1,4-cyclohexadiene was examined. Dichloroketene, which was easily prepared from trichloroacetyl chloride and Zn–Cu, reacted with 1,4-cyclohexadiene in the presence of POCl3 to afford novel racemic products of single addition (5) and double addition (6). The adducts 6 and 7 were reacted separately with MCPBA (meta-chloroperbenzoic acid), H2O2, LiAlH4, and cis-diol 10 was reacted with PCC (pyridinium chlorochromate) to afford lactone, alcohol, and ketone derivatives likely to exhibit biological activity. The structures of all the racemic molecules mentioned in the article were determined from 1H NMR, 13C NMR, MS, and IR data.