Electronic Structure and Reactivity of 2,2‐ethano‐1‐methylene 1,2,3,4‐tetrahydronaphthalene and 1,1‐ethano‐2‐methylene 1,2,3,4‐tetrahydronaphthalene

The electronic structures of the title compounds were calculated by ab initio STO‐3G minimal basis set following a MINDO/3 total geometry optimization of both. Their different reactivities towards electrophiles is suggested to result from different frontier (HOMO) orbital densities on the relevant atoms. Both MINDO/3 and STO‐3G calculations give similar results for the HOMO structures, where frontier density is comparable on exocyclic methylene and ethano bridge atoms in the 1,1‐ethano 2‐methylene analog, and much higher on the methylene than on the cyclopropyl atoms in the second molecule. Relative rates of reaction are also discussed.