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A Wittig-olefination-Claisen-rearrangement approach to the 3-methylquinoline-4-carbaldehyde synthesis.

ABSTRACT: Efficient syntheses are described for the synthetically important 3-methylquinoline-4-carbaldehydes 6a-h from o-nitrobenzaldehydes 1a-h employing a Wittig-olefination-Claisen-rearrangement protocol. The Wittig reaction of o-nitrobenzaldehydes with crotyloxymethylene triphenylphosphorane afforded crotyl vinyl ethers 2a-h, which on heating under reflux in xylene underwent Claisen rearrangement to give 4-pentenals 3a-h. Protection of the aldehyde group of the 4-pentenals as acetals 4a-h and subsequent oxidative cleavage of the terminal olefin furnished nitroaldehydes 5a-h. Reductive cyclization of these nitroaldehydes yielded the required 3-methylquinoline-4-carbaldehydes 6a-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.

SUBMITTER: Kulkarni MG

PROVIDER: S-EPMC3511006 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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A Wittig-olefination-Claisen-rearrangement approach to the 3-methylquinoline-4-carbaldehyde synthesis.

Kulkarni Mukund G MG Desai Mayur P MP Birhade Deekshaputra R DR Shaikh Yunus B YB Dhatrak Ajit N AN Gannimani Ramesh R

Beilstein journal of organic chemistry 20121011

Efficient syntheses are described for the synthetically important 3-methylquinoline-4-carbaldehydes 6a-h from o-nitrobenzaldehydes 1a-h employing a Wittig-olefination-Claisen-rearrangement protocol. The Wittig reaction of o-nitrobenzaldehydes with crotyloxymethylene triphenylphosphorane afforded crotyl vinyl ethers 2a-h, which on heating under reflux in xylene underwent Claisen rearrangement to give 4-pentenals 3a-h. Protection of the aldehyde group of the 4-pentenals as acetals 4a-h and subsequ ...[more]

PMID: 23209506

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