The configurations of isoxazolidines 2, 3, 5, 7, and 10–12 have been assigned by analysis of NMR coupling constants and by nuclear Overhauser effect difference spectroscopy (NOEDS). The preferred solution conformations of isoxazolidines 3 and 5 were determined to be as in 3A/5A. It is proposed that these conformations are adopted to take advantage of the anomeric effect and to alleviate the unfavorable stereoelectronic lone pair-lone pair interaction in the N-O portion of the molecule (gauche effect).
All Science Journal Classification (ASJC) codes
- Organic Chemistry