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Complex tauto‐ and rotamerism of 2‐(R‐phenyl)‐1,2,3,4‐tetrahydroquinazolines
Author(s) -
Gawinecki Ryszard,
Kolehmainen Erkki,
Kuczek Agnieszka,
Pihlaja Kalevi,
Ośmiałowski Borys
Publication year - 2005
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.927
Subject(s) - tautomer , chemistry , aniline , ring (chemistry) , endothermic process , medicinal chemistry , computational chemistry , stereochemistry , organic chemistry , adsorption
Detailed NMR spectral analysis of CDCl 3 solutions of 2‐(R‐phenyl)‐1,2,3,4‐tetrahydroquinazolines reveals three or four tautomeric forms. Apart from 2‐[(benzylideneamino)methyl]aniline, the other chain tautomeric forms are present only in minor quantities. In general, electron‐donating substituents increase the contribution of all chain forms. Lowering the temperature of the CDCl 3 solution of 2‐(R‐phenyl)‐1,2,3,4‐tetrahydroquinazolines decreases the content of the 2‐[(benzylideneamino)methyl]aniline form. At the same time, the amount of the ring form increases. Opening of the tetrahydropyrimidine ring in 2‐(R‐phenyl)‐1,2,3,4‐tetrahydroquinazolines was found to be an endothermic process especially for less electron‐donating substituents. Copyright © 2005 John Wiley & Sons, Ltd.