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A formal asymmetric synthesis of (−)-A26771B (1) has been achieved where optically active glycidol and Noyori asymmetric hydrogenation are applied to introduce asymmetric centers. Commercially available 1,7-octadiyne, (R)-glycidol and acetaldehyde are used as the starting materials. The outlined synthetic strategy involves fewer number of synthetic steps, applying simple chemical transformations. [ABSTRACT FROM AUTHOR]

Abstract: The enantioselective total synthesis of (−)-quinolactacin B (−)-1 was performed in seven steps and 33% overall yield from tryptamine. The synthesis features the use of ruthenium catalytic asymmetric hydrogen reaction to introduce the chirality in dihydro-β-carboline 2. Based on Noyori’s work, the hydrogenation using the (R,R)-TsDPEN-Ru complex produces dihydro-β-carbolines possessing the (S) absolute configuration, the corrected asymmetric center of the natural product. The synthetic quinolactacin B displayed optical rotations that was in accordance with that of the natural product, thereby supporting the (S) configuration for natural quinolactacin B. The final product’s stereochemical assignment is in agreement with that proposed by Nakagawa and co-workers. [Copyright &y& Elsevier]