Formamidinates

Other Access Routes for Symmetrical and Unsymmetrical Thiazolo Ds-es. Other functionally symmetrical reagents such as diethoxymethylacetate (method C), ethoxymethylenediethylmalonate (method D), diphenyl formamidine, and ethylisoformanilide condense with 2-methylthiazoliura to give the trimethine thiazolo dyes. 

The three methine carbons of the chain can be provided by 1.3.3-triethoxypropene (method C) or /S-anilinoacroleinanil, vinylog of diphenyl formamidine issued from the condensation of aniline on tetraal-koxypropane (method A). 

In many cases, the a-haloketone does not appear to be an intermediate in this reaction, since reagents such as sulfur trioxide, sulfuric, or 60% nitric add lead to 2-aminothiazole but with lower yields (11 to 43%). Formamidine disulfide [-S-C(=NH)NH2]2, a product of the oxidation of thiourea, seems to be the intermediate in this reaction, since upon treatment with ketones, it gives 2-aminothiazole (604). However, the true mechanism of this reaction has not yet been completely elucidated. 

Thiourea dioxide, or formamidine sulfinic acid, is an oxygenated thiourea derivative synthesized by the oxidation of thiourea with hydrogen peroxide. It has the chemical formula (NH2)NHCS02H and is tautomeric. 

Continuous polymerization in a staged series of reactors is a variation of this process (82). In one example, a mixture of chloroprene, 2,3-dichloro-l,3-butadiene, dodecyl mercaptan, and phenothiazine (15 ppm) is fed to the first of a cascade of 7 reactors together with a water solution containing disproportionated potassium abietate, potassium hydroxide, and formamidine sulfinic acid catalyst. Residence time in each reactor is 25 min at 45°C for a total conversion of 66%. Potassium ion is used in place of sodium to minimize coagulum formation. In other examples, it was judged best to feed catalyst to each reactor in the cascade (83). 

The primary synthesis of alkoxypyrimidines is exemplified in the condensation of dimethyl malonate with O-methylurea in methanolic sodium methoxide at room temperature to give the 2-methoxypyrimidine (854) (64M207) in the condensation of diethyl phenoxymalonate with formamidine in ethanolic sodium methoxide to give the 5-phenoxypyrimidine (855) (64ZOB1321) and in the condensation of butyl 2,4-dimethoxyacetoacetate with thiourea to give 5-methoxy-6-methoxymethyl-2-thiouracil (856) (58JA1664). 

Formamidine acetate [3473-63-0] M 104.1, m 159-161"(dec), 164 (dec), pK j( 12. Unlike the hydrochloride, the acetate salt is not hygroscopic. It is recrystd from a small volume of acetic acid, by addition of EtOH and the crysts are washed with EtOH then Et20 and dried in a vac. [Taylor, Ehrhart and Karanisi Org Synth 46 39 7966.]... 

The formamidine is prepared by heating the primary amine in DMF-dimethylac-etal (81-100% yield). Deprotection is effected by heating in EtOH with ZnCl2. LiAlH4 (Et20, reflux), hydrazine (AcOH, MeOH), KOH (MeOH, reflux), dilute ammonia (high yield), and coned. HCl (reflux, 65-90% yield) are also known to cleave the formamidine group. 

Heating a primary amine with dibenzylformamide-dimethyl acetal in CH3CN gives the formamidine in 49-99% yield. It is cleaved by hydrogenolysis (Pd(OH)2, MeOH, H2O, H2, 52-99% yield). ... 

These thiazoles are of specific interest in that they display exceptional pharmacological properties. Additionally, the unsaturated 2-aminonitrile functionality of the above thiazoles is recognized for its versatile functionality and therefore for its ensuing significance in the synthesis of heterocycles. The synthetic utility of thiazoles 13a-f is illustrated by the reactions of the unsaturated 2-aminonitrile functionality in compounds 13b and 13c with formamidine acetate, resulting in the thiazolopyrimidines 14a and 14c respectively. The synthesis of this relatively rare family of heterocycles provides a route into structurally similar bioactive compounds. ... 

Typically, an acetanilide (1 mol. equiv.) was treated with the Vilsmeier reagent generated from POCI3 (7 mol. equiv.) and V,V-dimethylformamide (DMF, 2.5 mol. equiv.) at 75 °C for 4 - 20 h. The reaction products were readily obtained by filtration after pouring the reaction mixture onto ice-water minor reaction products were isolated after basification of the filtrate. A variety of acetanilides were studied under these optimised reaction conditions and some significant observations were noted. Activated acetanilides 3 [e.g. R = 4-Me (70%), 4-OMe (56%)] reacted faster and in better yield to give quinolines 4 than other strongly deactivated systems 3 [e.g. R = 4-Br (23%), 4-Cl (2%), 4-NO2 (0%)] — in these cases, formamidines 5 and acrylamides 6 were the major reaction products. 

However, Sahasrabudhey thinks that the compound formed from 5-amino-1,2,3,4-thiatriazole does not have the composition CSN2H3CI, but (CSN2H4C1)2, and is in fact the dihydrochloride of formamidine disulfide, the oxidation product of thiourea. This con-... 

Regioselective lithiation of the formamidine 365 followed by tosylation afforded the corresponding 7-sulfone 367 which upon reaction with... 

Reaetion of l-amino-2-eyanoquinolinium perehlorate 769 with triethyl orthoformate gave the formamidine derivative 770 whieh upon treatment with primary amines afforded the triazoloquinolinium perehlorate 771 (90H289) (Seheme 134). 

N,N -Disubstituted formamidines, N-substituted from triethyl ortho formate and pnmary amines, 46, 41... 

Formaldoxime, 46,13 reaction with 2-bromo-4-methylben-zenediazonium chloride, 46,14 Formamidine, from hydrogen cyanide, 46,40... 

Formamidine, N,N -di-2-anthraquinonyI-metal complexes, 2,275 Formamidine, IV.AT-diaryl-metal complexes, 2, 275 Formamidine, N, N -dibenzyl-metal complexes, 2,276 Formamidine, IV.N -diisopropyl-metal complexes, 2, 276 Formamidinesulfinic acid technetium complexes, 6, 974 Formate dehydrogenases bacteria... 

Wahrend N,N -disubstituierte Harnstoffe von Lithiumalanat nicht angegriffen werden, erhalt man mit Natriumboranat in siedendem Pyridin mit mittleren Ausbeuten die entsprechenden N,N -disubstituierten Formamidine. N,N -Dialkyl-harnstoffe liefern die besten Ausbeuten, N,N -Diaryl-harnstoffe die schlechtesten3. 

N,N -Diathyl-N-phenyl-formamidin N,N -Dipropyl-N-phenyl-formamidin N,N -Dipropyl-N-butyl-formamidin N,N -Dimethyl-N-phenyl-formamidin... 

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