Reactions with Hydrazonoyl Halides. Part 42. Synthesis of Some New 2,3‐Dihydro‐1,3,4‐thiadiazoles, 2,3‐Dihydro‐1,3,4‐selenadiazoles and Triazolino[4,3‐a]pyrimidines.

Abstract

Ring closure reactions O 0130 Reactions with Hydrazonoyl Halides. Part 42. Synthesis of Some New 2,3-Dihydro-1,3,4-thiadiazoles, 2,3-Dihydro-1,3,4-selenadiazoles and Triazolino[4,3-a]pyrimidines. -The hydrazonoyl bromide (III) is used as precursor for the synthesis of a series of new heterocycles with a thia-or selenadiazole or a triazolo[4,3-a]pyrimidine structure. -(ABDELHAMID*, A. O.; ALKHODSHI, M. A. M.; Phosphorus, Sulfur Silicon Relat.

A new approach for the synthesis of some pyrazolo[5,1‐c]triazines and pyrazolo[1,5‐a]pyrimidines containing naphtofuran moiety

“…The later afforded the final product 6 through elimination of one molecule of water. Meanwhile, treatment of 3-dimethylamino-1-naphtho [2,1-b]furan-2-ylpropenone [20] (7) with 3a in ethanolic sodium acetate as buffer solution gave product identical in all respects mp., mixed mp., and spectra with 6a (Scheme 1). Analogously, treatment of the appropriate diazonium salt 3b-e with 2 in ethanolic sodium acetate afforded (naphtho [2,1-b]furan-2-yl) (8-phe-nylpyrazolo[5,1-c] [1,2,4]triazin-3-yl)methanone (6b), 3-(naphtho [2,1-b]furan-2-carbonyl)-pyrazolo [5,1-c] [1,2,4] triazine-8-carbonitrile (6c), ( [1,2,4]triazolo [3,4-c] [1,2,4] triazin-6-yl)(naphtho [2,1-b]furan-2-yl)methanone (6d), and benzo [4,5]imidazo [2,1-c] [1,2,4]triazin-3-yl-naphtho [2,1-b]furan-2-yl-methanone (6e), respectively.…”

“…Next, treatment of 3-dimethylamino-1-naphtho [2,1b]furan-2-ylpropenone (7) with each of acetylacetone, Scheme 2 ethyl acetoactate, or benzoylacetonitrile in boiling acetic acid containing ammonium acetate under reflux gave 1-(2-methyl-6-(naphtho [1,2-b]furan-2-yl)pyridin-3-yl)ethanone (19), ethyl 2-methyl-6-(naphtho [1,2-b]furan-2-yl) pyridine-3-carboxylate (20), and (2-amino-6-(naphtho [1,2-b]furan-2-yl)pyridin-3-yl)(phenyl)methanone (22), respectively (Scheme 3). Compound 20 was reacted with hydrazine hydrate to afford 2-methyl-6-(naphtho [1,2-b]furan-2-yl)pyridine-3-carbohydrazide (23).…”

“…Found: C,78.59;H,4.20;N,furan-2-yl)pyridin-3-yl)ethanone (19), ethyl 2-methyl-6-(naphtho [2,1-b]furan-2-yl)pyridine-3-carboxylate (20) and 6-(2-amino-6-(naphtho [1, 2-b]furan-2-yl)pyridin-3-yl)(phenyl)methanone (22). A mixture of the appropriate of acetylacetone, ethyl acetoacetate, or benzoylacetonitrile (5 mmole), 3-dimethylamino-1-naphtho [2,1-b]furan-2-ylpropenone (7) (1.32 g, 5 mmole), ammonium acetate (0.37 g, 5 mmole) in acetic acid (30 mL) was reflux for 4 h. The resulting solid which formed was collected and recrystallized from ethanol to give 19,20,furan-2-yl)pyridin-3-yl)ethanone (19). Brown crystals from diluted AcOH, yield (54%), mp: Anal.…”

Recent developments in chemical reactivity of N,N-dimethylenamino ketones as synthons for various heterocycles

“…It is worth mentioning herein that treatment of pyrazoles 246d-h with hydrazine hydrate under reux in ethanol led to the expected pyrazolopyridazines 249a-e, respectively. 4,99,110 Similar hyrazinolysis of pyrazoles 246a-c, in reuxing ethanol for two hours, resulted in the formation of only one isolable product. This product was identied as the 7-hydroxypyrazolopyridazine structure 247 that is formed via loss of a molecule of methanol, ethanol or aniline (Scheme 67).…”

“…107 In accordance with the observed formation of 5-unsubstituted pyrazoles, aminomethylene derivatives 241, 242 and 243 reacted with nitrilimines 245a-h (generated from hydrazonoyl halides 244a-k and triethylamine) to furnish the corresponding pyrazole derivatives 246a-k by cycloaddition and dimethylamine elimination. 4,99,110,111 Structure 246 was further established based on conversion of the isolated products 246a-e with hydrazine hydrate into the corresponding pyrazolo [3,4-d] pyridazines 247 and 249a-e, respectively. Clearly, these products can only be obtained from 5-unsubstituted isomer.…”