Synthesis of (±)-muscopyridine analogue using ring-expansion reaction of cyclic β-keto ester via conjugate addition to alkynyl imine

Synthesis of (±)-muscopyridine analogue was accomplished via the bicyclo-2-pyridone as a key intermediate, which was synthesized using ring-expansion reaction of the cyclic β-keto methyl ester with the alkynyl imine. The bicyclo-2-pyridone was transformed into the (±)-muscopyridine analogue in the following four steps in high yields: deprotection, pyridine formation, methylation, and hydrogenation.

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