| Abstract
| - A diastereoselective synthesis of 1-methyl-2-alkyl- and 2-alkyl-1,2,3,4-tetrahydroquinoline-4-carboxylic esters has been developed from methyl (2-nitrophenyl)acetate (1). The method involvesalkylation of 1 with an allylic halide, ozonolysis of the double bond, and catalytic hydrogenation.The final hydrogenation initiates a tandem sequence involving (1) reduction of the aromatic nitrogroup, (2) condensation of the aniline or hydroxylamine8 nitrogen with the side chain carbonyl, (3)reduction of the resulting nitrogen intermediate, and (4) reductive amination of the tetrahydroquinoline with formaldehyde produced in the ozonolysis to give a methyl (±)-1-methyl-2-alkyl-1,2,3,4-tetrahydroquinoline-4-carboxylate. Removal of the formaldehyde prior to hydrogenation givesthe simple (±)-2-alkyl derivatives. The products are isolated in high yield as single diastereomershaving the C-2 alkyl group cis to the C-4 carboxylic ester. The reaction has been extended to thesynthesis of tricyclic structures with similar high diastereoselection.
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