The Adamantane Rearrangement of syn- and anti-Tricyclo2,5>decane. Part II. Rearrangements Initiated by Regioselective Formation of Carbocations at C(3) and C(9)

Article abstract of DOI:10.1002/hlca.19880710420

The endo- and exo-alcohols 5-12 of syn- (1) and anti-tricyclo<4.2.1.1^2,5>decane (2) were treated with BF3/Et3SiH (ionic hydrogenation) in order to study the behaviour of the corresponding regioselectively generated carbocations at C(3) (a (syn), b (anti) and C(9) (c (syn), d (anti)).The anti-hydrocarbon 2 is practically the sole product obtained starting with the four 3-alcohols (via a -> b from 5 and 6 (syn) and via b from 9 and 10 (anti)).The four 9-alcohols in each case yield a mixture of 2-endo,3-endo- (3) and 2-exo,3-exo-trimethylene-8,9,10-trinorbornane (4) (via c -> e from 7 and 8 (syn) and via d -> f from 11 and 12 (anti)), but no hydrocarbon 2, i.e. none of the 1,3-H shifts c -> a and d -> b is involved.