A Trans-Stereoselective Synthesis of 3-Halo-4-alkyl(aryl)-NH-azetidin-2-ones
摘要:
Conrotatory ring closure of 1-halo-3-aza-4-alkyl-1,3-dienes in refluxing toluene gives rise to 3-halo-4-aryl-2-azetidinones in satisfactory yields. Dehalogenation of the resulting beta-lactams by tris(trimethylsilyl)silane furnished 3-unsubstituted azetidinones, valuable intermediates in the synthesis of biologically active compounds.
A new access to enantiopure 3-phthalimido-4-amino-5-(1-hydroxyalkyl) 1,5-dihydropyrrol-2-ones has been developed from 1,3-azadienes. Stereoselective Lewis acid catalyzed addition of a cyano group to an azadiene, followed by intramolecular ring closure, in a four-step one-pot synthesis, results in the formation of gamma-lactams in satisfactory yields. (C) 1999 Elsevier Science Ltd. All rights reserved.
Microwave-assisted solvent-free organic reactions: Synthesis of β-lactams from 1,3-azadienes
Ring-closure of 1,3-azadienes to beta-lactam rings is efficiently and quickly carried out under solvent-free conditions in an open-vessel microwave system. The synthesis of N-tert-butyldimethylsilyl azetidinones is reported. (C) 1998 Elsevier Science Ltd. All rights reserved.
A Trans-Stereoselective Synthesis of 3-Halo-4-alkyl(aryl)-NH-azetidin-2-ones
Conrotatory ring closure of 1-halo-3-aza-4-alkyl-1,3-dienes in refluxing toluene gives rise to 3-halo-4-aryl-2-azetidinones in satisfactory yields. Dehalogenation of the resulting beta-lactams by tris(trimethylsilyl)silane furnished 3-unsubstituted azetidinones, valuable intermediates in the synthesis of biologically active compounds.
Stereochemical aspects of the asymmetric synthesis of chiral α,β-dihydroxy phosphonates. Synthesis of α,β-dihydroxy phosphonic acids
The nature of the O-protecting group is crucial to obtain, in terms of diastereoselectivity and chemical yields, the best results. An abinitiomolecularorbitalstudy on 2-silyloxy propanal and MM2 studies on 2-alkoxy propanal show the existence of stable cyclic and acyclic conformers, which are presumably responsible for the high syn diastereoselectivity observed in the addition of non-metal carrying