The addition of n-butyllithium and íerí-butyllithium to 1,4-dihydronaphthalene 1,4-eredo-oxide (3) proceeds smoothly with concurrent cleavage to produce, after hydrolysis, the corresponding l,2-dihydro-as-2-butyl-lhydroxynaphthalenes 13 and 14. The cis configuration is the result of initial exo attack and this exo selectivity is observed with additions to benzonorbornadiene (9) where a cleavage does not occur. The adducts 13 and 14 are readily dehydrated to produce the corresponding /3-butylnaphthalenes 16 and 17, respectively.14 was dehydrated and purified to produce 17 in the same manner used for the preparation of 16 from 13.

The results from the electrophilic addition of bromine to croíí-7-bromo-o-phenyIbenzonorbornadiene (3) and syn-7-bromo-2-phenylnorbornene (2) suggest that initial approach of the bulky electrophile to these hindered systems is endo. This is in contrast to typical stepwise electrophilic additions to hindered norbornene systems without the phenyl group where exo attack is usually observed. The observations are interpreted to indicate that some stereoelectronic factor must be operating, at least in part, in controlling the preference for exo approach of an electrophile to a norbornene system.

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