Tricyclo- and --Systems

The oxymercuration of 1-substituted (i,e, H, Me, and C02Me) tricyclo[4,l,0,0 ]-heptanes with mercuric acetate affords norcaranyi- and norpinyl-mercury compounds. A synthesis of 3,4-benzotricyclo[4,l,0,0 ]heptene (692) has been reported in which the usual cyclopropylcarbene C—H insertion process is employed. Isomerization of (692) with silver perchlorate gave benzocycloheptatriene which is also formed in the thermal isomerization of (692). Reaction of (692) with n-ally 1 palladium(ii) chloride dimer yielded 2-methylene-l T-naphthalene which rearranged readily to 2-methylnaphthalene at room temperature a carbenoid mechanism appears to be involved. 

A simple conversion of 3-norcarene into trans-bishomobenzene has been discovered. The method involves reaction of (693), itself obtained in two standard steps from 3-norcarene, with Bp3,OEt2. Silver perchlorate-catalysed decomposition of (693) gave 2,3-homotropilidene quantitatively. 

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