Potassium isocyanate

The use of an organic isocyanate instead of potassium isocyanate gives a A-substituted hydantoin. 

Monocarbamoylation of diols is generally accomplished only with great difficulty. Reaction of the diol with an alkyl isocyanate is a possibility, but trimerization of the isocyanate frequently occurs [73]. The monocarbamic esters, which have PAF receptor antagonist activity, can be obtained however in acceptable yields via the phase-transfer catalysed in situ formation of the alkyl isocyanate from potassium isocyanate and an alkyl halide, and its subsequent reaction with the diol (see Scheme 3.8 for typical examples) [74], The diols tend to react more rapidly than do simple alcohols and m-diols are more effectively esterified that are /ra/rs-diols. Additionally, the longer the chain length between the hydroxyl centres, the less effective is the reaction. This has led to the reasonable hypothesis that a cyclic H-bonded intermediate between the two hydroxyl groups and the alkyl isocyanate are critical for the preferential and rapid formation of the carbamate. 

Carbimazole Carbimazole, the ethyl ester of 3-methyl-2-thioimidazolin-l-carboxylic acid (25.2.7), is synthesized by a simultaneons reaction of ethylenacetal of bromoacetaldehyde with methylamine and potassium isocyanate, forming 3-methyl-2-imidazolthione (25.2.6), which is further acylated at the nitrogen atom by ethyl chloroformiate, giving the desired product (25.2.7) [17-19]. 

POTASSIUM (HYDROXYDE de) (FRENCH) see PLJSOO POTASSIUM HYPERCHLORIDE see PLOSOO POTASSIUM HYPOCHLORITE see PLKOOO POTASSIUM lODATE see PLK2S0 POTASSIUM IODIDE see PLKSOO POTASSIUM lODOHYDRARGYRATE see NCPSOO POTASSIUM ISOCYANATE see PLC2S0 POTASSIUM ISOTHIOCYANATE see PLV7S0... 

A solution of dimethyl (2-morpholinocyclohept-2-enyl)sulfonium fluorosulfate (17.1 g, 50 mmol) in MeCN (200 mL) containing potassium isocyanate (16.2 g, 200 mmol) was refluxed for 25 min. The mixture was allowed to cool to rt, concentrated by removal of the solvent on a rotary evaporator and the residue was extracted with EtjO (5 x 150 mL). After removal of Et20 the product was isolated by bulb-to-bulb distillation yield 7.68 g (69%) bp 93°C/0.001 Torr. 

Kitamura et al. have described a remarkable high-yield photochemical synthesis of isoquinolinones (26) from the vinyl bromides (27) in the presence of water, dichloromethane, potassium isocyanate and a phase transfer agent. Binkley and Hehemann have described a novel high-yield procedure for the removal of protecting benzyl groups in carbohydrate derivatives. 

The reaction of benzoin with potassium isocyanate in DMSO or pyridine gives carbamates, which undergo cyclodehydration to form 4-oxazolin-2-ones. Instead of benzoin, a-bromocarbonyl compounds may be used147-149 Eq. (36)1. 

Other derivatives of 1-phenylethylamines include the urea 10, which is used in the preparation of chiral aminophosphonic acid (Section D.8), and which is formed by the action of potassium isocyanate on the amine 1 and (S)-JV-phenylethylhydroxylamine 11, used for the formation of chiral nitrones for 1,3-dipolar cycloadditions (Section D.l.6.1.2.1.)15. 

CAS 590-28-3 EINECS/ELINCS 209-677-9 Synonyms Cyanic acid, potassium salt Potassium isocyanate... 

Potassium isocyanate. See Potassium cyanate Potassium isopropyl xanthate CAS 140-92-1... 

Alkylamino-l-deoxy-D-fructoses reacted with potassium isocyanate in the presence of hydrochloric acid to give imidazole derivatives [e.g. (235)], while 1-amino-1-deoxy-D-gi/uco-heptulose gave the 4-[(polyhydroxy)a(kyl]pyrrole (236)... 

Scheme 10.20. A representation of the formation and base-induced decomposition of N-nitrosomethylurea to produce diazomethane (CH2N2) and potassium isocyanate (KCNO).

There are other amine surrogates that can be used to prepare amino acids by reaction with halides or other electrophilic species. Most are rather specific, but one shows some generality. Effenberger showed that reaction of methyl 5-bromohexan-oate 1.19) with potassium isocyanate gave 1.81. In this case, the isocyanate is the amine surrogate, and hydrolysis with concentrated HCl at 100°C gave 6-amino-hexanoic acid, 1.82, as its HCl salt. 4-Aminobutanoic acid, 3-aminopropanoic acid and 5-aminopentanoic acid were prepared in an identical manner.47... 

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