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Diels‐alder cycloadditions of N ‐substituted‐1,2‐dihydropyridines with 1,2,4‐triazoline‐3,5‐diones and maleimides
Author(s) -
Knaus E. E.,
Pasutto F. M.,
Giam C. S.,
Swinyard E. A.
Publication year - 1976
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570130312
Subject(s) - chemistry , substituent , degree of unsaturation , yield (engineering) , cycloaddition , bicyclic molecule , diels–alder reaction , medicinal chemistry , stereochemistry , organic chemistry , catalysis , materials science , metallurgy
The reaction of N ‐substituted‐1,2‐dihydropyridines 1 with 1,2,4‐triazoline‐3.5‐diones 2 and maleimides 9 proceeds stereospecifically to afford endo cycloaddition products. N ‐Acetyl‐1,2‐dihydropyridines react with 2 to afford a stereo isomeric mixture of 3 and 4 whereas those possessing a N ‐ethoxycarbonyl, methoxycarbonyl, methanesulfonyl or benzenesulfonyl substituent yield 3 exclusively: similar results are also obtained in reactions employing maleimides. Stereochemistry was assigned on the basis of nmr data and use was made of the anisotropic effects of the 7,8 unsaturation on the R 1 and R 2 substituents.