期刊
TETRAHEDRON
卷 71, 期 37, 页码 6424-6436出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.tet.2015.02.080
关键词
Stereocontrolled total synthesis; Alkaloid; Enantioselective catalysis; Intramolecular Heck reaction
资金
- National Institutes of Health [R01-HL25854, R01-GM098601, F32-GM09660]
- NIH [P30-CA22572]
- Drug Discovery and Structural Biology Core facility
A unified strategy for enantioselective total synthesis of all stereoisomers of the [2+2] family of quadrigemine alkaloids is reported. In this approach, two enantioselective intramolecular Heck reactions are carried out at the same time on precursors fashioned in four steps from either meso- or (+)-chimonanthine to form the two critical quaternary carbons of the peripheral cyclotryptamine rings of these products. Useful levels of catalyst control are realized in either desymmetrizing a mesa precursor or controlling diastereoselectivity in elaborating C-2-symmetric intermediates. None of the synthetic quadrigemines are identical with alkaloids isolated previously and referred to as quadrigemines A and E. In addition, we report improvements in our previous total syntheses of (+)- or (-)-quadrigemine C that shortened the synthetic sequence to 10 steps and provided these products in 2.2% overall yield from tryptamine. (C) 2015 Elsevier Ltd. All rights reserved.
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