Keten. Part VI. The adducts of dimethylketen with diarylnitrones

Abstract

of Sheffield Dimethylketen reacts with CN-diphenylnitrone to form the 1 : 1and 2 : 1 -adducts 2-(2-benzylideneiminophenyl) -2-rnethylpropanoic acid (IXa) and a(3,3-dimethyl-2-oxoindol-l -yl) benzyl isobutyrate (Illa), respectively. Similar adducts are formed from C-phenyl-N-(o-tolyl) nitrone.THE reactions of ketens with nitrones have been inthis work the reaction of dirnethylketen with CNvestigated by Staudinger.2 Several CN-diarylnitrones diphenylnitrone was examined in the hope that this were reported to form 1 : l-adducts with diphenylketen, might be a useful model system. It was immediately and a 1 : 2-adduct (nitrone to keten) was obtained from obvious, however, that the nitrone reacted in a totally triphenylnitrone. The structures proposed for these compounds all contained pentacovalent nitrogen and need not be considered further. of the structure of the 1 : l-adduct of diphenylnitrone PhCH = N \ & different manner. It reacted with an excess of dimethylketen in ethyl acetate solution to give a high yield of a 1 : 2-adduct, C,,H,,NO,.We assign the structure 3 T.

Rearrangement of N-Oxyenamines and Related Reactions

“…Interaction of N -arylnitrones with ketenes proceeds via a [3 + 2]-cycloaddition to a carbonyl group . A further reaction cascade furnishes oxindoles. − In Scheme is shown the recently developed asymmetric method, where chiral induction is achieved by use of Garner’s aldehyde derivative 167 . ,, The bulky nitrogen substituent PG plays an important role in creating the optical purity.…”

“…It should also be noted that nitrones, which are incapable of achieving the conformation required for cycloaddition or rearrangement (i.e., 169 ), follow other reaction pathways . Dichloroketene after hydrolysis leads to the isatins 170 .…”