Reaction of 2‐acyl‐3‐aminobenzofurans with hydrazines

Abstract

While 2‐acetyl and 2‐benzoyl‐3‐aminobenzofurans did not react with hydrazine, monomethyl‐ and N,N‐dimethylhydrazine to give the related hydrazones, their 3‐N‐(p‐toluenesulfonyl) derivatives afforded them smoothly in good yields. Depending upon reaction conditions, products arising from hydrazone cyclization to benzofuropyrazoles and/or from furan ring cleavage at the C2O bond to give 5‐(2‐hydroxyphenyl)pyrazoles were also formed. The formation of these products depends upon hydrazones configuration and is discussed. Only (E)‐isomers appear to undergo furan ring opening. In acidic media at room temprature either the hydrazones or the monomethylhydrazones gave the same related α‐azines. Microanalyses, ir, uv, 1H‐nmr and ms spectra are in agreement with the proposed structures.

Structure of N-(2-acetyl-3-benzofuranyl)-p-toluenesulfonamide

“…It may be noted, however, that in isomer (2) both the hydroxyl and the secondary methyl evidence for a hydrogen bond between the N atom of the -NH-SO 2 group and the O atom of the acetyl group, causing the carbonyl group to be syn with respect to the N atom. (Gatta & Settimj, 1984) in order to check their activity 0(4) 2811 (2) 1490 (3) on the central nervous system (Landi Vittory,Gatta,N 27O2 (2) 263 (3) C (2) 1567 (3) 838 (4) Chiavarelli & Ciriaci, 1964). For this purpose, the c(3) 1744 (2) 1057 (3) reactivity towards hydrazines of 2-acyl-3-aminobenzo-c(4) 769 (2) 2033 (3) furans (I) and of their corresponding 3-N-p-toluene-c (5) 47 (3) 2322(4) C(6) -1004 (3) 3212 (4) sulfonylbenzofurans (II), was compared.…”

Facile, mild and efficient synthesis of azines using phosphonic dihydrazide

“…The spectral data for 10a,b were in agree-ment with those reported. [36,37] Similarly, reaction of isatin (11) and 2 in ethanol under reflux for 3 h afforded (3Z,3'E)-3,3'-(hydrazine-1,2-diylidene)bis(indolin-2-one) (12) in 85% yield (Scheme 5). The Xray crystal structure of 12 is shown in Figure 6.…”

“…m.p. 163-164 C [36] ), red, yield, 88%. The spectral data for 10a was in agreement with those reported.…”

Synthesis, Cytotoxicities and DNA-Binding Affinities of Benzofuran-3-ols and Their Fused Analogs

“…13,14) Thus, one-step reaction of compounds 1a-i with hydrazine hydrate in refluxing acetic acid afforded compounds 2a-i in 10-92%. These compounds were fully characterized by MS (low resolution (LR) and high resolution (HR)) and NMR ( 1 H and 13 C) (see Experimental).…”