The stereochemistry of nitrone cycloadditions. d1-allosedamine and d1-sedridine.

✍ Scribed by Joseph J. Tufariello; Sk.Asrof Ali

• Book ID: 104237339
• Publisher: Elsevier Science
• Year: 1978
• Tongue: French
• Weight: 268 KB
• Volume: 19
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)85694-x

✦ Synopsis

The regiochemical characteristics of the cycloaddition reactions of nitrones with dipolarophiles have been explored in some detail.lS2 The stereochemistry of these additions has received somewhat less attention although it is clear that an efficient utilization of dipolar cycloadditions in synthesis is in substantial measure dependent on a knowledge of the stereochemical factors involved. The stereochemistry of both intermolecular and intramolecular nitrone-dipolarophile cycloadditions has been examined to some extent. The latter are complicated by constraints introduced by the fixed geometries of the interacting functionalities.3 Previously examined nitrone cycloadditions have exhibited a range of stereoselectivities. Thus, C-phenyl-N-methylnitrone (1) reacts with a-methylstyrene to afford a 55:45 ratio of the two possible stereoisomers (2a and 2b)4, of &and a,5 --and with styrene to give a 2:l ratio respectively.

'gH5 CH3