Alkyl N‐methylfuroxanylcarbamates. Synthesis and structure. II

Abstract

From 3‐methyl‐4‐furoxancarboxylic acid hydrazide and 4‐methyl‐3‐furoxancarboxylic acid hydrazide the corresponding azides have been synthesized. 3‐Methyi‐4‐furoxancarboxylic acid azide normally underwent the Curtius reaction to give the expected carbamic acid derivative. The degradation of 4‐methyl‐3‐furoxancarboxylic acid azide led to the N‐(4‐methylfuroxan‐3‐yl)‐carbamic acid derivative at low temperatures and to N‐(3‐methylfuroxan‐4‐yl)carbamic acid derivative at higher temperatures.

Synthesis and NMR Spectroscopic Characteristics of a Series of Hydrazide‐Hydrazones Containing Furoxan Ring Derived from Isoeugenoxyacetic Acid

“…The chemical shifts of H10 and C10 of the methyl group attached with the furoxan ring are in the range 2.02–2.35 ppm (Table 3) and 7.6–11.55 ppm (Table 5), respectively. These data indicate that the methyl group is adjacent to the N‐oxide oxygen of the furoxan ring , as shown in Scheme , that is, the isomerization has not taken place.…”

“…The chemical shifts of H10 and C10 of the methyl group attached with the furoxan ring are in the range 2.02-2.35 ppm (Table 3) and 7.6-11.55 ppm (Table 5), respectively. These data indicate that the methyl group is adjacent to the N-oxide oxygen of the furoxan ring [26], as shown in Scheme 2, that is, the isomerization has not taken place. Secondly, it is possible that the considered hydrazidehydrazones may exist as geometrical isomers in respect to the N¼C double bonds and as conformers about N-C(O) bond as shown in Figure 2.…”

“…Gasco et al showed that the chemical shift of a ring methyl group adjacent to the N‐oxide oxygen of furoxans occurs at 2.30–2.33 ppm, while a ring methyl group remote from it or a ring methyl group of furazan appears at 2.50–2.53 ppm. The signal of the ring methyl group (10‐H) of K , L , M , N appears as a singlet at 2.01–2.35 ppm (Table 1) indicating that the methyl group is at position 3 of the furoxan ring and the furoxan ring was not reduced by hydrazine hydrate to furazan ring.…”

Some imines and azo compounds containing furoxan ring synthesized from methylisoeugenol

“…Gasco and colleges [8] showed that the chemical shift of a ring methyl group adjacent to the N-oxide oxygen of furoxans occurs at 2.30-2.33 ppm, while a ring methyl group remote from it, at 2.50-2.53 ppm. The signal of the ring methyl group (10-H) of 1-15 appears as a singlet at 1.96-2.08 ppm (Table 1) indicating that the methyl group is at position 3 of the furoxan ring.…”

4-Methyl-1,2,5-oxadiazole-3-carbonitrile in the synthesis of 1,2,5-oxadiazolyl-1,2,4-oxadiazoles

“…7 4 Methyl 1,2,5 oxadiazole 3 carbonitrile (1). A finely tritu rated mixture of amide 2 (0.76 g, 6 mmol) and P 2 O 5 (3 g, 20 mmol) was placed in a Claisen flask with an air condenser.…”