In:
Chemische Berichte, Wiley, Vol. 107, No. 11 ( 1974-11), p. 3574-3588
Abstract:
Cycloaddition Reactions of Heterocumulenes, III. Thermal Cycloaddition Reactions of Heterocummulenes with 2‐Dialkylaminoazirines In the thermal cycloaddition reactions of the highly reactive azirines 1a, b with heterocumulenes, a 1,4‐dipole is formed in the first reaction step, which is stable in the case of the isothiocyanates 22d – f , the thioketenes 12a , b , and carbon disulfide ( 23d , e , f ; 13a – c ; 14 ). 1a reacts with the isothiocyanates 22a – c to form the dipoles 28a – c via the thiazolines 26 . The structure of the 1,4‐dipoles is proved by spectroscopic methods, hydrolysis, and protonation. In the carbon disulfide‐dipole 14 the free activation enthalpy of the hindered rotation of the CN‐double bond could be measured. The 1,4‐dipole from phenylisocyanate is stabilized by reaction to the hexahydro‐ s ‐triazine 16 . In the reactions with p ‐toluenesulfonyl isocyanate ( 17 ) and with tert ‐butylcyanoketene ( 6 ) the intermediatly formed 1:1‐adduct is split into 19 and 7 . The reaction of 1a with diphenylketene ( 2 ) leads to the oxazoline 4 .
Type of Medium:
Online Resource
ISSN:
0009-2940
DOI:
10.1002/cber.v107:11
DOI:
10.1002/cber.19741071112
Language:
English
Publisher:
Wiley
Publication Date:
1974
detail.hit.zdb_id:
779-1
