Abstract
A variety of allylic nitro compounds can be prepared by taking advantage of a unique feature of the nitro group arising from its high electron-withdrawing property. They undergo (i) partial reduction into α, β-unsaturated ketones, aldehydes, or oximes, (ii) replacement of the nitro group by various nucleophiles in the presence of Pd (0) catalyst or stannic chloride, or under solvolysis conditions and (iii) rearrangement of the nitro group or the double bond. Further, 2- (nitromethyl) - and 2- (phenylsulfonylmethyl) -2-cycloalken-1-ones, allylic compounds activated by a keto group, are shown to be readily available and to undergo (i) regioselective SN2 type substitution of the nitro or sulfonyl group by soft nucleophiles via either ionic or radicalchain mechanism, depending on the nature of the nucleophiles and the structure of the substrates, and (ii) eventual SN2' reaction by organocopper reagents and silylated nucleophiles with the aid of trialkylsilyl chloride or triflate and fluoride ion. Chiral 2- (aminomethyl) -2-cycloalken-1-ones, the SN2 products, are utilized for asymmetric synthesis of optically active 3-substituted 2-methylenecycloalkan-1-ones with high enantiomeric excess.
