%0 Journal Article
%T A Wittig-olefination每Claisen-rearrangement approach to the 3-methylquinoline-4-carbaldehyde synthesis
%A Mukund G. Kulkarni
%A Mayur P. Desai
%A Deekshaputra R. Birhade
%A Yunus B. Shaikh
%J Beilstein Journal of Organic Chemistry
%D 2012
%I 
%R 10.3762/bjoc.8.197
%X Efficient syntheses are described for the synthetically important 3-methylquinoline-4-carbaldehydes 6a每h from o-nitrobenzaldehydes 1a每h employing a Wittig-olefination每Claisen-rearrangement protocol. The Wittig reaction of o-nitrobenzaldehydes with crotyloxymethylene triphenylphosphorane afforded crotyl vinyl ethers 2a每h, which on heating under reflux in xylene underwent Claisen rearrangement to give 4-pentenals 3a每h. Protection of the aldehyde group of the 4-pentenals as acetals 4a每h and subsequent oxidative cleavage of the terminal olefin furnished nitroaldehydes 5a每h. Reductive cyclization of these nitroaldehydes yielded the required 3-methylquinoline-4-carbaldehydes 6a每h in excellent yields. Therefore, an efficient method was developed for the preparation of 3-methylquinoline-4-carbaldehydes from o-nitrobenzaldehydes in a simple five-step procedure.
%K acetal
%K Claisen rearrangement
%K oxidative cleavage
%K ring-closure
%K Wittig olefination
%U http://dx.doi.org/10.3762/bjoc.8.197