Facile stereoselective synthesis of cis- and trans-3-alkoxyazetidin-2-ones
作者:Aman Bhalla、Paloth Venugopalan、Shamsher S. Bari
DOI:10.1016/j.tet.2006.06.062
日期:2006.8
A highly stereoselectivesynthesis of cis- and trans-3-alkoxy-3-phenyl/benzylthioazetidin-2-ones is described. The reaction of α-chlorosulfide-β-lactams with various alcohols catalyzed by a Lewis acid such as ZnCl2 in the presence of molecular sieves (3–4 Å) leads to cis-3-alkoxy-3-phenyl/benzylthio-β-lactams whereas treatment of potassium 2-alkoxy-2-phenylthioethanoate with appropriate Schiff's base
Lewis acid mediated functionalization of β-lactams: mechanistic study and synthesis of C-3 unsymmetrically disubstituted azetidin-2-ones
作者:Aman Bhalla、Suman Rathee、Sachin Madan、Paloth Venugopalan、Shamsher S. Bari
DOI:10.1016/j.tetlet.2006.05.160
日期:2006.7
A convenient and efficientroute to novel unsymmetrically disubstituted azetidin-2-ones is described. β-Lactam carbocation equivalents of type 1 and active aromatic substrates in the presence of a Lewis acid promote a facile and stereoselective C-3 substitution to provide monosubstituted β-lactams (3,4) and symmetrically disubstituted β-lactams (5). cis-3-(4′-Methoxyphenyl)-3-phenylthioazetidin-2-ones
C-3 β-lactam carbocation equivalents: versatile synthons for C-3 substituted β-lactams
作者:Aman Bhalla、Sachin Madan、Paloth Venugopalan、Shamsher S. Bari
DOI:10.1016/j.tet.2006.03.050
日期:2006.5
An efficient and operationally simple strategy for the synthesis of differently C-3 monosubstitutcd (9) and disubstituted (10) monocyclic beta-lactams is described. This involves reaction of beta-lactam carbocation equivalents (8) with an active aromatic, aliphatic and heterocyclic substrates in the presence of a Lewis acid. (c) 2006 Elsevier Ltd. All rights reserved.