Isocyanates chlorocarbonyl isocyanate

I.3.4.2.4. Heterocumulenes The 1,3-dipolar cycloaddition of substituted ben-zonitrile oxides to the C=N group of chlorocarbonyl isocyanate C1C(0)N=C=0 gives 3-aryl-4-chlorocarbonyl-5-oxo-4,5-dihydro-l,2,4-oxadiazoles 172 in 75%-80% yield (340). A similar reaction with chlorosulfonyl isocyanate, C1S02N=C=0, affords 4-unsubstituted oxadiazolinones 173 (341). 

The reaction of dimethyl amino(butylamino)methylenemalonate (1364) and Af-(chlorocarbonyl)isocyanate in benzene afforded (l,3,5-triazin-2-ylidene)malonate (1365) in 52% yield and the hydrochloride salt of the starting material (1364 x HC1) (76ZOR2253). 

Dihydro-1,2,4-oxadiazol-5-ones (74) cannot be 7V-acylated by either chlorocarbonyl isocyanate or trichloroacetyl chloride. However, preparation of 4-chlorocarbonyl compounds (73) can be achieved by cycloaddition of stable nitrile oxides to the C=N double bond of chlorocarbonyl isocyanate <888994, 90ZOR339). Compounds (73) decompose with ammonia, primary amines, or primary amides to isocyanates and (74) (Scheme 26). 

Stable arylnitrile oxides undergo cycloaddition to the G=N bond of chlorocarbonyl isocyanate to give compounds (185) <90ZOR339>. In contrast, cycloaddition of nitrile oxides to trichloroacetyl isocyanate occurs across the C=0 double bond leaving the isocyanate group unaffected. From... 

Cyclization of quinazolin-4(3//)-one with an excess of methyl isocyanate gave the 1,3,5-triazino[ 1,2-u]quinazoline-1,3,6-trione (643) (84H501). A one-pot synthesis of 1,3,5-triazino[ 1,2-u ]quinazolines (645) was carried out by reacting 2-amino-4-phenylquinazolines (644) with chlorocarbonyl isocyanate (85S892). 

The reaction between amidines and N-chlorocarbonyl isocyanate gives the ionic compounds (133 Scheme 71). If the amidine is replaced by a urea, the 1,3-disubstituted isocyanurate (134) is formed in very good yield. Even potentially labile substituents, e.g. f-butyl, survive this reaction intact. Thioureas also may be used they form salts (135) which... 

Syntheses of heterocycles with participation of chlorocarbonyl isocyanate 93T3227. 

Chlorocarbonyl isocyanate has been found active for the conversion of substituted pyri-dazinones to the corresponding chloropyridazines (equation 166)1083. 

A simple approach to the 2-azaallenium ions 361, based on the reaction of carbonyl compounds with chlorocarbonyl isocyanates 360, was described152. No mechanism for this reaction was suggested, but the scheme displayed in equation 101 can apply based on the considerations stated above86. 

Cyclic 1 1 and 1 2 adducts are also obtained frombis(trimethylsilyl)carbodiimide and ben-zenesulfonyl isocyanate. However, reaction of the same carbodiimide with chlorocarbonyl isocyanate affords the triazine derivative 44. ... 

Reaction of l-(trimethylsilyl)pyrazole with chlorocarbonyl isocyanate gives 1-oxo-l/f-pyrazolo[l,2-a][l,2,4]triazol-4-ium-3-olates <88CB895>. Another interesting reaction of the same compound is with jV-fluoropyridinium fluoride to afford 2-(pyrazol-l-yl)pyridine (24), a useful chelating agent (see Section 3.01.5.3.4(v)) <93JOC4476>. 

The use of phenoxycarbonyl isocyanate for cyclizing an aminoazole in pyridine is well known (p. 289). This reaction may also be effected by refluxing the reactants in a neutral high-boiling solvent. Chlorocarbonyl isocyanate (review [2929, 3802]) is also a very effective reagent for cyclizing such amines. 

Triazinethiones (169) are synthesized from 5-alkylisothioureas and acyl isothiocyanates <87MI 612-04, 91PS(62)275>. A-Aminotriazinedione derivatives (170) are obtained when 5-alkyl-isothiosemicarbazones are condensed with diphenyl dicarbimidate (Scheme 51). The dicarbimidate was produced by reaction of chlorocarbonyl isocyanate with phenol <84GEP3409065>. 

Chlorocarbonyl isocyanate reacts directly with ureas in toluene at reflux temperature to form triazinetriones (171), which are useful as herbicides (Equation (30)) <83GEP3147879,84GEP3314739). 

Akteries and Jochims reported the synthesis of l,4-bis(4-methoxyphenyl)-l,3,5-triazine-2,4,6-(17/,37/,5//)-trione (177) when chlorocarbonyl isocyanate was reacted with di-(4-methoxy-phenyl)carbodiimide. The chloro intermediate was not isolated but hydrolyzed with water to give (177) (Scheme 52) <86CB1133>. Products similar to (177) (e.g. (171)) are available by the condensation of chlorocarbonyl isocyanate directly with ureas. 

Whereas direct reaction of 3,4,5-trimethyl pyrazole with chlorocarbonyl isocyanate is unsuccessful <77AG789>, treatment of its activated trimethylsilyl derivative (302) with this 1,3-bielectrophile, followed by heating, yields (303) in 35% yield (Equation (43)) <83H(20)23>. 

Reaction of A -substituted thioamides (391) with chlorocarbonyl isocyanate at room temperature affords good yields of 1-imino derivative (392) which can be quantitatively A -methylated with diazomethane to (393) (Scheme 82) <848771 >. 

The synthesis of cyanurates 215 started with condensation of the corresponding amines with an excess of nitrobiuret 214 (method A, Scheme 33). Subsequent ring closure with diethyl carbonate and sodium ethoxide gave compound 215 in good yields. Similar results could be obtained by the reaction of the same amines with A -chlorocarbonyl isocyanate (method B, Scheme 33) <2002CEJ2288>. 

Reaction of resin-bound amino acids 239 with isocyanates yields resin-bound ureas, which react further with chlorocarbonyl isocyanate to afford the resin-bound 1,3-disubstituted l,3,5-triazine-2,4,6-triones 240, selectively (Scheme 37). Subsequent, selective alkylation at the N-5 position, to yield the resin-bound 1,3-disubstituted... 

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