‘Off-template site’ intramolecular nitrone cycloaddition (INC) reactions on sugar-derived allylic ethers—a study on the substituent effect and synthesis of furano-pyrans
作者:G.V.M Sharma、K Ravinder Reddy、A Ravi Sankar、A.C Kunwar
DOI:10.1016/s0040-4039(01)01889-5
日期:2001.12
Sugar-derived allylic ethers having one or two substituents on the terminal olefinic carbon centre were subjected to intramolecular nitrone cycloaddition (INC) reactions resulting in bicyclo[4.3.0] systems. The exclusiveness of product formation may be attributed to the effect of substituents.
3-O-Allylcarbohydrate nitronecycloaddition (3-OACNC) furnished pyran and oxepane derivatives from 3-O-allyl hexose N-benzyl nitrones and 3-O-allyl furanoside-5-aldehyde N-benzyl/methyl nitrones. The regioselectivity of 3-OACNC was found to depend on the following factors (a) the structural nature of the nitrone (b) substitution and stereochemistry at 3-C of the carbohydrate backbone (c) substitution
Synthesis, high-resolution NMR spectroscopic analysis, and single-crystal X-ray diffraction of isoxazoline tetracycles
作者:Mirta L Fascio、Angel Alvarez-Larena、Norma B D'Accorso
DOI:10.1016/s0008-6215(02)00258-6
日期:2002.11
Three isoxazoline tetracycles were obtained enantiomerically pure by intramolecular 1,3-dipolar cycloaddition. The characterization of the new compounds was performed by high-resolution H-1 and C-13 NMR spectroscopy. The relative configuration of the new chiral centers was determined by NOESY experiments and confirmed by single-crystal X-ray structural analysis. (C) 2002 Elsevier Science Ltd. All rights reserved.
Stereoselective Synthesis of Chiral Oxepanes and Pyrans through Intramolecular Nitrone Cycloaddition in Organized Aqueous Media
作者:Amrita Chatterjee、Pranab K. Bhattacharya
DOI:10.1021/jo051414j
日期:2006.1.1
A highly stereoselective surfactant-catalyzed intramolecularnitrone (formed by dehydration in water) cycloaddition in aqueous media leading to exclusive formation of a single isomer is reported. Either oxepane or pyran is formed from 3-O-allyl furanoside derivatives, which constitute the framework of a large number of biologically active compounds. Therefore, the environmentally friendly, efficient