A-chloro isocyanates

Likewise, reaction of a-chloro isocyanate 172 with N-trimethylsilyl-N ... 

Antimony pentachloride reacts with a-chloro isocyanates to form l-oxa-3-azabutatriene salts, R2C=N+=C=0 SbCle, 26, which undergo [2+2+2] cycloaddition reactions with disubstituted cyanamides to give 1,3,5-oxadiazinium salts 27. ... 

The reaction of 2-chloro-2-arylnaphthalides 396 with amines, followed by treatment with thionyl chloride and then antimony pentachlo-ride (73KGS1127), or the intramolecular C-acylation of a-chloro-a-(naphthyl-1/isocyanate 397 by the action of antimony pentachloride (84CB3211), leads to N-protonated or N-alkylated 9-aryI-2-oxonaphtho[c[Pg.66]

Pyrazinedicarbonyl dichloride (144) and cyclohexyl isocyanate gave 3-[a-chloro-a-(cyclohexylimino)acetyl]-2-pyrazinecarbonyl chloride (145) (PhH, 20°C, 1 h then 60°C, 45 min 54%).523 Also other examples.275 1091... 

In the reaction of a-chloroheterocumulenes, such as a-chloro-N-sulfinylamines (X = NSO) or or-chloro isocyanates (X = NCO) with bis(trimethylsilyl)carbodiimicle displacement of the chloro group by a carbodiimide group is observed to give 48. 

CYCLOADDITIONS f-Butyicyanoketene. a-Chloro-N-cyclohexylpropanaldoxime. Chlorosulfonyl isocyanate. Dichloroke-tene. Dimethyl acetylenedicarboxylate. Diphenyl ketene, 2-Methoxyallyl bromide. 2-Methoxy-6-methyl-l,4,3,5-oxathiadia-zine 4,4-dioxide. Oxygen, singlet. 4-Phen-yl-l,2,4-triazoline-3,5-dione. Silver fluoro-borate. Trimethylsilyldiazomethane. 

A 2-chloro-isocyanate cyclizes on standing in a desiccator to a product which contains this ring. 

A) Phenyl isocyanate (I) is chlorinated in chloroform, and the /i-chloro-phenylcarbonimidoyl dichloride (II) obtained is reacted with dimethylamine to give p-chlorophenylimino chlorocarbonic acid dimethylamide (III). This is treated with... 

Isothiocyanates. Both a-chloro aldoximes and nitroalkanes give isothiocyanates on reaction with thiourea. The former needs a base (e.g., E N) to generate nitrile oxides in situ, and the latter requires both a base and a dehydrating agent, such as 4-chlorophenyl isocyanate. 

The formation of diastereomeric ureides from chloro-fomnate reagents has been used in quantitative assays and for the preparative separation of both secondary and tertiary amines. Quantitative assays for promethazine, a tertiary amine of the phenothiazine group of pharmaceuticals, have been developed. Maibaum [100] carried out a three-stage reaction in which the racemic promethazine was reacted with vinyl chloroformate and the carbamate was subsequently hydrolysed to the secondary amine. The enantiomeric ratio of the amine was then determined as the urea following reaction with a chiral isocyanate. In a later development, Witte et al. [lOI] directly derivatized the same compound with (— )-menthyl chloroformate (17) and separated the diastereomers by HPLC. (—)-Menthyl chloroformate has also been used to resolve the enantiomers of nomicotine as... 

Reactions with N-(chlorocarbonyl)isocyanate a-Chloro-N-carbonylureas from azomethines... 

In a related piece of work, imidazolines have been prepared from A -chloro-N-phenyl amidines and enamines. (Scheme 79). Pyrazomycins have been synthesized by the Roche group, the key step being the preparation of the pyrazolone ring by the addition of toluene- -sulphonyl azide to the anion from diethyl acetone dicarboxylate (Scheme 80). Imidazolidines (201) have been prepared by the action of isocyanates and isothiocyanates with an aziridine ester a dipolar intermediate is implicated. Imidazolidine-4,5-diones have been prepared by the... 

X5lenol is an important starting material for insecticides, xylenol—formaldehyde resins, disinfectants, wood preservatives, and for synthesis of a-tocopherol (vitamin E) (258) and i7/-a-tocopherol acetate (USP 34-50/kg, October 1994). The Bayer insecticide Methiocarb is manufactured by reaction of 3,5-x5lenol with methylsulfenyl chloride to yield 4-methylmercapto-3,5-xylenol, followed by reaction with methyl isocyanate (257). Disinfectants and preservatives are produced by chlorination to 4-chloro- and 2,4-dich1oro-3,5-dimethylpheno1 (251). 

Irradiation of the A-bromo- or N- chloro-azetidin-2-ones (71) in the presence of alkenes, alkynes or radical donors induces rearrangement to the /3-haloalkyl isocyanates (72) via a... 

A solution of 54 g (0.64 mol) of propyl isocyanate in 60 ml of anhydrous dimethylform-amide was added to a cold, well-stirred suspension of 81 g (0.42 mol) of dry p-chloro-benzenesulfonamide in 210 ml of anhydrous triethylamine during the course of 20 to 30 minutes. The mildly exothermic reaction was completed by allowing it to stand at room temperature for about 5 hours. The reaction mixture was then slowly added to 3 liters of cold 20% acetic acid during the course of about one hour, constant agitation being maintained throughout the addition. 

A. Toluene diisocyates (TDI), xylene isocyanates, chloro-TDI, bromo-TDI, dichloro-TDI, and trichloro-TDI... 

Reaction of 2-cyanomethylpyridine with iV-(l-aryl-l-chloro-2,2,2-trifluoroethyl)-iV -(4-methylphenyl)carbodiimides, and with (1,1,2,2,2-pentachloro- and l,l-dichloro-2,2,2-trifluoroethyl)isocyanates or A-methoxycarbonyl-l,2,2,2-tetrachloro-, — l-chloro-2,2-trifluoroacetaldehyde imines afforded 3-aryl-4-cyano-l-(4-methylphenyl)imino-3-trifluoromethyl-2,3-dihydro-17/-pyrido[l,2-f]pyrimidines and 4-cyano-3-trichloro-, 4-cyano-3-trifluoro-17/-pyrido[l,2-4pyrimidin-l-ones, respectively <2004CHE47>. Refluxing 2-cyanomethylpyridine and iV-(l-aryl-l-chloro-2,2,2-trifluoroethyl)isocyanates in benzene furnished l-aryl-4-cyano-l-trifluoromethyl-l,2-dihydro-3//-pyrido[l,2-4pyrimidin-3-ones. However, when the solution of the isocyanate was added dropwise to the solution of 2-cyanomethylpyridine, and the reaction mixture was then treated with NEt at room temperature, the isomeric 3-aryl-4-cyano-3-trifluoromethyl-2,3-dihydro-l//-pyr-ido[l,2-dpyrimidin-l-ones were obtained. Reaction of l-(acetyl- and benzoylmethylene)-6,7-dimethoxy-l,2,3,4-tetra-hydroisoquinolines with PhCONCS yielded 1-acetyl-, 1 -benzoyl-9,10-dime thoxy-3-pheny 1-6,7-dihydro-2//-pyrimido[6,l- ]isoquinoline-2-thiones <2003SL2369>. 

Loblolly pine modified by 1,6-diisocyanatohexane (HDI) was found to be resistant to attack by G. trabeum at a WPG of 26 % (Chen, 1992c). At 26 % WPG, 6 % of bonded chemical was lost during a 12-week soil decay test. When moist wood was used for reaction, the HDI reacted mainly to form ureas and biurets. It was stated that the decay resistance of HDI modified wood was probably due to the inability of the modified cell wall to absorb sufficient amounts of water to support decay. Although wood reacted with chloro-sulphonyl isocyanate lost only 1.3 % mass when exposed to G. trabeum in a decay test, it was reported that 50 % of the bonded chemical was lost in this test. 

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