Synlett 2008(18): 2831-2835  
DOI: 10.1055/s-0028-1083542
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Prolinamide/PPTS-Catalyzed Hajos-Parrish Annulation: Efficient Approach to the Tricyclic Core of Cylindricine-Type Alkaloids

Xiao-Ming Zhang, Min Wang, Yong-Qiang Tu*, Chun-An Fan, Yi-Jun Jiang, Shu-Yu Zhang, Fu-Min Zhang*
State Key Laboratory of Applied Organic Chemistry & Department of Chemistry, Lanzhou University, Lanzhou 730000, P. R. of China
Fax: +86(931)8912582; e-Mail: tuyq@lzu.edu.cn;
Further Information

Publication History

Received 20 June 2008
Publication Date:
15 October 2008 (online)

Abstract

A series of Wieland-Miescher ketone analogues bearing highly functionalized substituents are efficiently constructed in high enantioselectivities and good yields using catalytic amounts of prolinamide and PPTS. We have successfully utilized this reaction as a key step to synthesize the tricyclic core of cylindricine type alkaloids.

16

See ref. 3e; we had increased the yield to 65% over two steps by using H2O-AcOH (100:1.5) as the solvent and 2 equiv of MVK under reflux conditions in the second step.

20

CCDC 696349 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.