Reaction of ?,?-dimethyl-?-(1-phe nyl-3-methyl-4-pyrazolyl)- ? , ?-butenolide with primary amines and ammonia

Intramolecular Reversible Addition Reactions to the C=O Group

“…But one rarely succeeded in obtaining both individual isomers. This was the case for the N-unsubstituted amide [33], the N-benzylamide [218,220], and the anilide [189] of levulinic acid, as well as for the N-benzylamide of 2,2-dimethyl-3-(3-methyl-l-phenylpyrazolyl-4-carbonyl)propionic acid [238] (see Table 9). …”

“…(238) [38,81]. The interacting groups are rigidly fixed at a short distance, which is shown by the high equilibrium constant (KT = 3000) determined by the potentiometric method [38].…”

“…Both opposing effects may explain the increased stability of the ring isomer for N-methylamides only. A great number oflevulinic [33,189,199,218,220,230,231,234,235], other 3-acylpropionic (R 1 = alkyl) [199,220,236,237], 3-aroylpropionic [33,197,199,202,203], and methylsubstituted acylpropionic [141,200,221,231,237,238] ami des were synthesized and their structures strictl,Y proven by means of spectroscopic methods. But one rarely succeeded in obtaining both individual isomers.…”

“…3-Acylpropionic amides, bearing methyl groups in the chain, predominantly, also possess a cyclic structure [141,200,221,231,237,238].…”