Synthesis of the N-alkyl isomers of 4-ethoxycarbonyl-or-acetyl-3(5)-alkyl-or-aryl-5(3)-acylpyrazoles from 3(2H)-furanones. Structure determination

Abstract

Synthesis of isomeric N-alkyl-3,4,5-trisubstituted pyrazoles are described from reaction of 3(2H)-furanones with alkylhydrazines or alternatively by alkylation of corresponding N-unsubstituted pyrazoles. Their structures are unambiguously established by 'H and 13C NMR studies. By comparison of the data of the N-alkylpyrazoles with those of the N-unsubstituted pyrazoles, the 5-methyl and 5-phenyl structures were found as the predominant form for these pyrazoles.Recently, we have reported that the 3(2H) -furanones are interesting substrates which undergo ring opening by nucleophilic reagents, leading to new cyclic c o m p o~n d s . l -~ Our studies concerning the reaction of hydrazine hydrate with 3(2H)-furanones 1-4 have led to a useful procedure to obtain Trialkylketenimines were prepared by reaction of a-cyano enamines w i t h methylmagnesium iodide in ethereal solution. Condensation of trialkylketenimines w i t h p r i m a r y amines afforded the corresponding amidines.

Syntheses of 5‐Alkylthio‐1,3‐diaryl‐1,2,4‐triazoles.

“…8.17 (m, 2H, H 13,17 ), 8.10 (d,J=8.8 Hz,2H,H 8,10 ), 7.96 162.45 (C 3 -triazole), 154.83 (C 6 ), 141.64 (C 5 -triazole), 139.47 (C 9 ), (d, J=8. 8 Hz,2H,H 7,11 ),3H,H 14,15,16 8 Hz,2H,H 7,11 ),3H,H 14,15,16 ), 3.43 (C 9 ), 130.12 (C 12 ), 129.61 (C 15 ), 128.65 (C 8,10 ), 128.42 (C 13,17 ), (q, J=7 Hz, 2H, CH 2 ), 3.10 (s, 3H, SO 2 CH 3 ), 1.50 (t, 126.41 (C 14,16 ), 123.33 (C 7,11 ), 44.22 (SO 2 CH 3 ), 28.3 (CH 2 ), J=7 Hz, 3H, CH 3 ).…”

“…2c 8.15 (dd,J=8.8 Hz,J=5.6 Hz,2H,H 13,17 ), 8.10 (d, J= 164.92 (C 3 -triazole), 162. 15 (d,J=85 Hz,C 15 ), 154.32 (C 6 ), 9.2 Hz,2H,H 8,10 ),7.96 (d,J=9.2 Hz,2H,H 7,11 ),7.15 (t,141.64 (C 5 -triazole), 139.57 (C 9 ), 128.88 (C 8,10 ), 128.64 (d, J=8. 8 Hz,2H,H 14,16 ), 3.12 (s, 3H, SO 2 CH 3 ), J=8.…”

“…The structure of compounds 3a, 2a and 9 could also be confirmed by 13 C-NMR. It is known [10][11][12] that where heteroaromatic carbon atoms have otherwise identical chemical environment, the carbon attached to a pyridine-like nitrogen atom is more deshilded than that bound to pyrrole-like nitrogen. The diff e r e n c e between the two types of chemical shifts values in isomers where the structure is fixed by alkyl groups, and also in the case of different tautomeric forms measured at low temperatures, is about 8-12 ppm.…”

Reaction of 2-(2-oxoethylidene)furan-3(2H)-ones with isopropylidenehydrazides of aromatic carboxylic acids: Synthesis of 3-hydroxy-3-(2-oxoethyl)-2,3-dihydropyridazin-4(1H)-ones

“…The reactions of 2-ylidenefuran-3(2H)-ones with hydrazine or arylhydrazines lead to the formation of hydrazino derivatives of 3-oxofuran [1], 3-acylpyrazoles [2][3][4], or 3-alkyl(ylidene)-substituted pyridazine-4(1H)-ones [4]. It is known that the action of aroylhydrazines on 3-oxofuran-2(3H)-ylideneacetates leads to the formation of 1-aroylamino-2-hydroxy-3-oxo-2,3-dihydro-1H-pyrrol-2-ylacetic esters [5].…”

Syntheses of 5‐alkylthio‐1,3‐diaryl‐1,2,4‐triazoles

“…The structure of compounds 3a, 2a and 9 could also be confirmed by 13 C-NMR. It is known [10][11][12] that where heteroaromatic carbon atoms have otherwise identical chemical environment, the carbon attached to a pyridine-like nitrogen atom is more deshilded than that bound to pyrrole-like nitrogen. The diff e r e n c e between the two types of chemical shifts values in isomers where the structure is fixed by alkyl groups, and also in the case of different tautomeric forms measured at low temperatures, is about 8-12 ppm.…”