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N ‐Vinylketenimine
Author(s) -
Capuano Lilly,
Braun Claudia,
Kühn Frank
Publication year - 1992
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.199219920104
Subject(s) - chemistry , isoquinoline , pyrimidinones , yield (engineering) , in situ , wittig reaction , oxazines , organic chemistry , medicinal chemistry , stereochemistry , metallurgy , materials science
N ‐Vinylketenimines. The title compounds 5 are generated in situ from N ‐vinyl‐iminotriphenylphosphoranes 1 and ketenes 2 in a Wittig‐type reaction. The phosphoranes are useful intermediates for the preparation of numerous heterocycles as illustrated by the formation of 1,3‐oxazines 8 , pyridinones 9 , pyrimidinones 10 and 1,3‐thiazines 11 . Water adds readily to 5 to yield vinylacetamides 7 , whereas thermal rearrangement gives rise to the isoquinoline 4 or the spiro system 6 , respectively. Under very mild conditions, crystalline precursors (type 3 ) of the N ‐vinylketenimines, which still contain the triphenylphosphonio group, have been isolated. These react like the N ‐vinylketenimines generated in situ, giving however less byproducts.