A general enantioselective route to the chamigrene natural product family
Described in this report is an enantioselective route toward the chamigrene natural product family. The key disconnections in our synthetic approach include sequential enantioselective decarboxylative allylation and ring-closing olefin metathesis to form the all-carbon quaternary stereocenter and spirocyclic core present in all members of this class of compounds. The generality of this strategy is demonstrated by the first total syntheses of elatol and the proposed structure of laurencenone B, as well as the first enantioselective total syntheses of laurencenone C and α-chamigrene. A brief exploration of the substrate scope of the enantioselective decarboxylative allylation/ring-closing metathesis sequence with fully substituted vinyl chlorides is also presented.
Additional Information© 2010 Elsevier. Received 15 April 2010; revised 28 April 2010; accepted 29 April 2010. Available online 4 May 2010. This publication is based on work supported by Award No. KUS-11-006-02, made by King Abdullah University of Science and Technology (KAUST). Additionally, the authors wish to thank the NIH-NIGMS (R01 GM080269-01, postdoctoral fellowships to D.E.W. and I.C.S.), Abbott, Amgen, Bristol-Myers Squibb, Merck, and Caltech for generous funding; Materia, Inc. for their kind donation of catalyst 49 used in these studies; Professors Mercedes Cueto and Karen L. Erickson for their kind donation of natural samples of elatol (1); Professor Adusumilli Srikrishna for copies of 1H and 13C NMR spectra of synthetic (±)-laurencenone C ((±)-8) and (±)-α-chamigrene ((±)-5); and Professor Peter B. Dervan and David M. Chenoweth for use of their HPLC. Finally, B.M.S. thanks all of his current and former co-workers and colleagues who have made working at Caltech over the past 10 years such an enjoyable experience. As evidenced by the collaborative nature of this project, the spectacular environment at Caltech is one-of-a-kind and second-to-none.
Accepted Version - nihms-203918.pdf
Supplemental Material - f.pdf