摘要:
In the course of our studies of the structure-activity relationships of himbacine 1, a potent antagonist of the M-2 subtype of muscarinic receptor, the four title compounds, 2, ent-2, 3, and ent-3, were synthesized with a highly stereoselective intermolecular Diels-Alder reaction of tetrahydroisobenzofuran 4 with achiral furan-2(5H)-one 5 as a key step, followed by simultaneous optical resolution and epimer separation of the racemic intermediates. Among these compounds, 3-demethylhimbacine (3-norhimbacine) 2, bearing an absolute configuration corresponding to that of 1, was found to show more potent muscarinic M2 subtype receptor binding activity than natural 1. (C) 2002 Elsevier Science Ltd. All rights reserved.