Radical and ionic nucleophilic substitution reactions on α-Alkyl-γ-(p-nitrophenyl)allyl derivatives

Abstract

The nature of the reaction between α-alkyl-γ-(p-nitrophenyl)allyl chlorides (1)-(3), which have the general form p-O₂NC₆H₄CH=CHCH(Cl)R, and a variety of nucleophiles depends on the alkyl group R and the nucleophile. The chloride (1) (R = Me) undergoes ionic (S_N2 and subsequent Michael addition) processes with the salt (7) of 2-nitropropane to give products (15) and (16) whereas the chloride (2) (R = Pr¹) gives a mixture of products (17) and (18) which are shown to arise by a radical-chain nucleophilic substitution process, with allylic rearrangement-an S_RNl' reaction-and ionic processes respectively. The chloride (3) (R = Bu^t) gives the S_RN1' product (25) with the salt (7). Other nucleophiles with (2) and (3) appear to react by ionic (S_N2 and S_N2') and/or S_RNl' processes; e.g. (3) gives an excellent yield of the malononitrile (32) by an S_N2' process when treated with the sodium salt (9).