The highly diastereoselective synthesis of the marine natural product, (-)-manzacidin B, is described. A novel copper-catalyzed aldol reaction of the alpha-methylserine-derived aldehyde with an isocyanoacetate possessing (1R)-camphorsultam as the chiral auxiliary proceeded in a highly diastereoselective manner to give the (4R,5R,6R)-adduct, which was converted into manzacidin B in a few steps. (C) 2012 Elsevier Ltd. All rights reserved.
Practical Syntheses of Proposed and Revised Manzacidin B and Their Congeners
作者:Kuppusamy Sankar、Hasibur Rahman、Pragna P. Das、Eswar Bhimireddy、B. Sridhar、Debendra K. Mohapatra
DOI:10.1021/ol203466m
日期:2012.2.17
concise and highlystereoselectivetotalsynthesis of manzacidin B and its congeners has been developed following chelation-controlled syn-epoxidation and Lewis acid catalyzed intramolecular regioselective epoxide ring opening to generate the quarternary amine center. Elaboration of the triol moiety to the target molecule was achieved in good overall yield, representing practical total syntheses of
The highly diastereoselective synthesis of the marine natural product, (-)-manzacidin B, is described. A novel copper-catalyzed aldol reaction of the alpha-methylserine-derived aldehyde with an isocyanoacetate possessing (1R)-camphorsultam as the chiral auxiliary proceeded in a highly diastereoselective manner to give the (4R,5R,6R)-adduct, which was converted into manzacidin B in a few steps. (C) 2012 Elsevier Ltd. All rights reserved.
[reaction: see text] Four possible stereoisomers of manzacidin B were synthesized using stereochemically defined synthetic routes via the azide 7 and oxazoline 11 starting with the (R)-alpha-methyl Garner aldehyde 5. Comparisons of the spectroscopic data of the synthetic isomers 4a-d with those of the natural manzacidin B revised the proposed structure 3 to (4S,5S,6R)-4d.