Enantio- and Diastereoselective Synthesis of 1,5-<i>syn</i>-(<i>Z</i>)-Amino Alcohols via Imine Double Allylboration: Synthesis of <i>trans</i>-1,2,3,6-Tetrahydropyridines and Total Synthesis of Andrachcine
作者:Christophe Allais、William R. Roush
DOI:10.1021/acs.orglett.7b00995
日期:2017.5.19
A stereoselective synthesis of trans-1,2,3,6-tetrahydropyridines 8 is described. This synthesis proceeds via intramolecular Mistunobu reactions of 1,5-syn-(Z)-amino alcohols 7, which were prepared by a highly diastereo- and enantioselective double-allylboration reaction of aldehyde 5 and silylimine 6. The chiral bifunctional γ-borylallylborane 9E was generated in situ by hydroboration of allene 3 with
Development of a double allylboration reagent targeting 1,5-syn-(E)-diols: application to the synthesis of the C(23)–C(40) fragment of tetrafibricin
作者:Philippe Nuhant、Jeremy Kister、Ricardo Lira、Achim Sorg、William R. Roush
DOI:10.1016/j.tet.2011.06.008
日期:2011.9
Interest in the synthesis of the C(23) C(40) fragment 2 of tetrafibricin prompted us to develop a new method for the synthesis of 1,5-syn-(E)-diols. Toward this end, the kinetically controlled hydroboration of allenes 6, 33, ent-39, 42, and 45 with the Soderquist borane 25R were studied. Tetrabutylammonium allenyltrifluoroborate 45 gave superior results and was utilized in a double allylboration sequence with two different aldehydes to provide the targeted 1,5-syn-(E)-diols in generally high yields (72-98%), and with high enantioselectivity (>95% ee), diastereoselectivity (dr >20:1), and (E)/(Z) selectivity (>20:1). This new method was applied to the synthesis of the C(23) C(40) fragment 2 of tetrafibricin. (C) 2011 Elsevier Ltd. All rights reserved.