Premium
Synthesis of 4‐Aminopyrimidines from 1,2,4‐Oxadiazoles, II A General Method for the Preparation of 4‐Substituted 6,7‐Dihydro‐9,10‐dialkoxy‐2 H ‐pyrimido[6,1‐ a ]isoquinolin‐2‐imine Hydrochlorides
Author(s) -
Korbonits Dezső,
Kiss PÁL,
Bata Imre,
Héja Gergely,
Simon KáLmáN,
Kolonits PáL
Publication year - 1987
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19871200625
Subject(s) - chemistry , isomerization , ring (chemistry) , imine , medicinal chemistry , catalysis , catalytic hydrogenation , cleavage (geology) , chloride , organic chemistry , geotechnical engineering , fracture (geology) , engineering
5′‐Substituted 1‐[(1,2,4‐oxadiazol‐3‐yl)methyl]‐3,4‐dihydroisoquinolines ( 7 ) were reduced by NaBH 4 selectively to give the corresponding tetrahydroisoquinolines ( 8 ) which underwent ring isomerization to pyrazolo[5,1‐ a ]isoquinolines ( 9 ). Catalytic hydrogenation of 7 in the presence of hydrogen chloride, in turn, gave by reductive cleavage of the N–O bond of the 1,2,4‐oxadiazole ring and subsequent dehydration, quite generally, 4‐substituted pyrimido[6,1‐ a ]isoquinolin‐2‐imine hydrochlorides ( 11 ).