Enantioselective Synthesis and Racemization of (-)-Sinoracutine

Volpin, Giulio; Vepřek, Nynke A.; Bellan, Andreas B. and Trauner, Dirk (2017): Enantioselective Synthesis and Racemization of (-)-Sinoracutine. In: Angewandte Chemie-international Edition, Vol. 56, No. 3: pp. 897-901

Abstract

Sinoracutine is a recently isolated alkaloid with unusual stereochemical and biological properties. It features an unprecedented tetracyclic 6/6/5/5 skeleton that bears an N-methylpyrrolidine ring fused to a cyclopentenone. Interestingly, both enantiomers of sinoracutine have been independently isolated from the same plant, yet the molecule does not appear to occur as a racemate. Here, we present a short synthesis of (-)-sinoracutine that relies on a highly diastereo-selective Pauson-Khand reaction and a Mandai-Claisen reaction to install the quaternary stereocenter. Our work establishes the absolute configuration of the levorotatory isomer and suggests that the optical purity of sinoracutine varies in nature due to its gradual racemization. Experimental evidence supports this proposal, and a plausible mechanism for the racemization is provided.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Subjects: 500 Science > 540 Chemistry
• ISSN: 1433-7851
• Language: English