{"id":11694,"date":"2022-12-02T03:49:24","date_gmt":"2022-12-01T19:49:24","guid":{"rendered":"https:\/\/www.pyrazoles-derivatives.com\/?p=11694"},"modified":"2022-12-02T03:49:24","modified_gmt":"2022-12-01T19:49:24","slug":"beyer-hanss-team-published-research-in-chemische-berichte-in-89-cas-23286-70-6-2","status":"publish","type":"post","link":"https:\/\/www.pyrazoles-derivatives.com\/?p=11694","title":{"rendered":"Beyer, Hans’s team published research in Chemische Berichte in 89 | CAS: 23286-70-6"},"content":{"rendered":"

Beyer, Hans published the artcileThiazoles. XXIX. The condensation products of thiosemicarbazide with ethyl \u03b1-chloroacetoacetate and a novel ring contraction of 2-amino-5-methyl-6-carbethoxy-1,3,4-thiadiazine to 3-methyl-4-carbethoxy-5-aminopyrazole<\/i><\/b>, Synthetic Route of 23286-70-6<\/a>, the publication is Chemische Berichte (1956), 1652-8, database is CAplus.<\/p>\n

On condensation of AcCHClCO2<\/sub>Et (I) with H2<\/sub>NNHCSNH2<\/sub> (II), 4-methyl-5-carbethoxy-2-thiazolylhydrazine (III), MeC(:NNHCSNH2<\/sub>)CHClCO2<\/sub>Et (IV), or 3-amino-4-methyl-5-carbethoxy-2-thiazolone imide (V) is formed, depending upon the pH and temperature Refluxing 13.3 g. 1-acetylthiosemicarbazide and 8.5 g. NaOAc in 75 cc. absolute EtOH in a CO2<\/sub> atm., adding dropwise within 15 min. 16.5 g. I in 25 cc. absolute EtOH, and refluxing the mixture another hr. yield 96% N’-acetyl-N-(4-methyl-5-carbethoxy-2-thiazolyl)hydrazine (VI), fine needles, m. 227\u00b0, which (12.2 g.), refluxed in 75 cc. absolute EtOH 1 hr. with 5.3 cc. concentrated HCl, gives 88% III.HCl, needles, m. 189-90\u00b0. III.HCl is also formed in 80% yield when 4.1 g. I in 3 cc. EtOH is added (15 min.) to 2.28 g. II in 20 cc. EtOH at 50\u00b0 (free III, liberated with NaOAc, 100%, leaflets, m. 186\u00b0; di-Ac derivative, prepared by heating 2.01 g. III or 2.43 g. VI with 15 cc. Ac2<\/sub>O 20 min. on a water bath, 84%, needles, m. 198\u00b0; tri-Ac derivative, prepared by heating 2.01 g. III 15 min. in 10 cc. Ac2<\/sub>O containing 5 drops concentrated H2<\/sub>SO4<\/sub>, prisms, m. 131\u00b0; monoformyl derivative, prepared by refluxing 2.01 g. III 1 hr. with 10 cc. 98% HCO2<\/sub>H, 92%, fine needles, m. 205\u00b0). Boiling 2.01 g. III 15 min. in 25 cc. Me2<\/sub>CO yields 92% acetone (4-methyl-5-carbethoxy-2-thiazolyl)hydrazone, silky needles, m. 143\u00b0; PhCOMe derivative, 95%, m. 118\u00b0. Adding dropwise (1 hr.) 16.4 g. I to 9.1 g. II in 50 cc. 2N HCl at 0\u00b0 yields 100% IV, also formed in 78% yield by mixing the 2 reagents in alc. solution without HCl; IV decompose on storage. Adding at 70\u00b0 9.5 g. IV to 60 cc. PrOH and bringing the mixture quickly to the boil give 74% 2-amino-5-methyl-6-carbethoxy-1,3,4-thiadiazine-HCl, decompose about 90\u00b0 [free base (VII), liberated with saturated NaOAc solution, fine yellow needles, decompose above 80\u00b0; after 2-3 days it decompose with the formation of 3-methyl-4-carbethoxy-5-aminopyrazole (VIII)]. Heating VII or IV with the calculated amount of p-O2<\/sub>NC6<\/sub>H4<\/sub>CHO (IX) in EtOH yields 40% IX (4-methyl-5-carbethoxy-2-thiazolyl)hydrazone, yellow needles, m. 244\u00b0; BzH analog, pale yellow leaflets, m. 189\u00b0, is prepared by treating III.HCl in 2N HCl with BzH and NaOAc, or in 93% yield by condensation of equimolar amounts of III and BzH. Heating 7.2 g. VII.HCl in 50 cc. concentrated HCl 15-20 min. on a water bath and concentrating the filtered solution to 1\/3 its volume yield 66% V.HCl, fine needles, m. 242-4\u00b0 (decomposition), which is also formed in 43% yield when 8.2 g. I is added to 4.6 g. II in 30 cc. hot concentrated HCl and the solution concentrated to 0.5 its volume (free V, needles, m. 130\u00b0; di-Ac derivative, prisms, m. 107-8\u00b0). Adding 1.28 g. NaNO2<\/sub> in H2<\/sub>O to 2.4 g. V.HCl in 25 cc. 2N HCl at 0\u00b0 and pouring the ice-cooled solution into 1.2 g. PhNMe2<\/sub> in dilute HCl give 2-(p-dimethylaminophenylazo)-4-methyl-5-carbethoxythiazole (X).HCl, deep blue crystals, from which NH4<\/sub>OH liberates the free X, red-brown leaflets, m. 205\u00b0; X is also obtained in 43% yield when 3.7 g. 2-amino-4-methyl-5-carbethoxythiazole is diazotized at 0\u00b0 and the diazonium solution is treated with 2.4 g. PhNMe2<\/sub>. Refluxing 9.5 g. VII.HCl 1 hr. in 50 cc. 2N alc. HCl and filtering off the S formed yield 80% VIII.HCl, m. 187-9\u00b0 [free base, leaflets containing 1 mole H2<\/sub>O, m. 69\u00b0, m. 113\u00b0 (H2<\/sub>O-free); nitrate, prisms, m. 197-8\u00b0 (decomposition); mono-Ac derivative, prisms, m. 91\u00b0]. Treating 4.1 g. VIII.HCl in 15 cc. H2<\/sub>O and 3 cc. concentrated HCl at 0\u00b0 with 1.38 g. NaNO2<\/sub> in 7 cc. H2<\/sub>O, pouring the diazonium solution into ice cold 30% H3<\/sub>PO2<\/sub>, keeping the mixture overnight at 0\u00b0, and adding saturated NaOAc solution give 3-methyl-4-carbethoxypyrazole-H2<\/sub>O, m. 46\u00b0 (HCl salt, needles, sinters 145\u00b0, m. 160\u00b0). Diazotizing 2.5 g. VIII.HCl, adding the diazonium solution to 1.2 g. PhNMe2<\/sub> in dilute HCl, and then adding NaOAc give 70% 3-methyl-4-carbethoxy-5-(p-dimethylaminophenylazo)pyrazole, stout orange prisms, m. 172\u00b0.<\/p>\n

Chemische Berichte published new progress about 23286-70-6. 23286-70-6 belongs to pyrazoles-derivatives, auxiliary class Pyrazole,Amine,Ester, name is Ethyl 5-amino-3-methyl-1H-pyrazole-4-carboxylate, and the molecular formula is C7H11N3O2, Synthetic Route of 23286-70-6<\/a>.<\/p>\n

Referemce:
https:\/\/en.wikipedia.org\/wiki\/Pyrazole<\/a>,
Pyrazoles – an overview | ScienceDirect Topics<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Chemische Berichte published new progress about 23286-70-6. 23286-70-6 belongs to pyrazoles-derivatives, auxiliary class Pyrazole,Amine,Ester, name is Ethyl 5-amino-3-methyl-1H-pyrazole-4-carboxylate, and the molecular formula is C7H11N3O2, Synthetic Route of 23286-70-6<\/a>.<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[798,131],"tags":[717],"class_list":["post-11694","post","type-post","status-publish","format-standard","hentry","category-23286-70-6","category-pyrazoles-derivatives","tag-m-w150-200"],"yoast_head":"\nBeyer, Hans's team published research in Chemische Berichte in 89 | CAS: 23286-70-6 | pyrazoles-derivatives<\/title>\n<meta name=\"description\" content=\"Beyer, Hans published the artcileThiazoles. XXIX. 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