Synfacts 2009(8): 0817-0817  
DOI: 10.1055/s-0029-1217578
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of (+)-Quebrachamine

Contributor(s):Philip Kocienski, Stewart Eccles
E. S. Sattely, S. J. Meek, S. J. Malcolmson, R. R. Schrock, A. H. Hoveyda*
Boston College, Chestnut Hill and, Massachusetts Institute of Technology, Cambridge, USA
Design and Stereoselective Preparation of a New Class of Chiral Olefin Metathesis Catalysts and Application to Enantioselective Synthesis of Quebrachamine: Catalyst Development Inspired by Natural Product Synthesis
J. Am. Chem. Soc.  2009,  131:  943-953  
Further Information

Publication History

Publication Date:
23 July 2009 (online)


Significance

Quebrachamine is an Aspidosperma alkaloid that is an adrenergic blocker. This synthesis is noteworthy for the highly enantioselective ring-closing cross-metathesis (G → I) using a chiral molybdenum catalyst which is stereogenic at the metal center.

Comment

The catalyst H was made by a diastereoselective desymmetrization (dr = 7:1) of a Mo bispyrrolide precursor with one equivalent of monosilyl-protected octahydrobinaphthol in benzene at room temperature. No improvement on the impressive enantiomeric ratio was seen when diastereoisomerically pure H was used.