A General Approach to 1‐Hydroxymethylquinolizidine and 8‐Hydroxymethylindolizidine Stereoisomers: Synthesis of (+)‐Epitashiromine and Formal Syntheses of (+)‐Epilupinine and (+)‐Tashiromine. Issue 32 (9th October 2013) - Thorat, Rakesh G.
Abstract: A general strategy for the synthesis of structurally and stereochemically related indolizidine and quinolizidine alkaloids was developed. The methodology involves regio‐ and stereoselective 1, 3‐dipolar cycloadditions of simple nitrones with ephedrine‐derived alkylidenemorpholinones. The intermediate isoxazolidines can be converted into either the indolizidine or the quinolizidine motif depending on the nitrone and the substituent on the dipolarophile. The approach was applied to the synthesis of (+)‐epitashiromine and to the formal syntheses of (+)‐epilupinine and (+)‐tashiromine. Abstract : A flexible strategy involving cycloadditions of simple nitrones with ephedrine‐derived alkylidenemorpholinones is developed for the synthesis of structurally and stereochemically related indolizidine and quinolizidine alkaloids. The methodology is employed in the synthesis of (+)‐epitashiromine and in the formal syntheses of (+)‐epilupinine and (+)‐tashiromine.