The chemical and electrochemical reductions of 5-bromodecalone [(4aα,5α,8aβ)-5-Bromooctahydronaphthalen-1(2H)-one] and 4-bromodecalone [(4α,4aβ,8aα)-4-bromooctahydronaphthalen- 1(2H)-one]

Abstract

5-Bromodecalone (1) was prepared by the reaction of potassium bromide in acetonitrile on(4aα,5α,8aβ)-5-tosyloxyoctahydronaphthalen-l(2H)-one (15) with apparent retention of configuration. It was also prepared by hydrogen bromide cleavage of (3aRS,3bRS,7aSR)-octahydro-7H-cyclopenta[1,3]cyclopropa[1,2]benzen-7-one (17). On reaction with sodium potassium alloy ketone (1)gives α-decalone (33) and ketone (17) as the principal products whereas reduction with tributylstannane gives only ketone (33). Electrochemical reduction of ketone (1) gives trans-cyclodec-5-en-1-one (3) as well as ketones (17) and (33). 4-Bromodecalone (2) was prepared from(4a,4aα,8aβ)-4-tosyloxyoctahydronaphthalen-1(2H)-one (29), by the reaction with potassium bromidein acetonitrile, with inversion of configuration. Electrochemical reduction of ketone (2) gives trans-1-acetyl-2-vinylcyclohexane (36), α-decalone (33), (E)-cyclodec-4-en-1-one (4) and (laRS,-1bSR,5aRS,6aRS)-octahydrocycloprop[a]inden-6(6aH)-one(24).