Reactions with isocyanates, 391 hydroxide

A similar product is obtained from the reaction of anhydro-4(5)-hydroxy-l,2,3-triazolium hydroxide (398). In this case reaction with DMAD occurred in 1 hour in boiling benzene. Extrusion of methyl isocyanate from the initial 1 1 cycloadduct (399) occurred during the reaction giving (400). 

The cyclized analog of meralluride is prepared by a similar synthesis. Thus, condensation of camphoric acid (42) (obtained by oxidation of camphor) with ammonia gives the bicyclic succinimide (44). Reaction with allyl isocyanate followed by ring opening and then reaction with mercuric acetate affords the mercury derivative (45) as the acetate rather than the hydroxide as above. Reaction with sodium chloride converts that acetate to the halide (46). Displacement on mercury with the disodium salt of thioglycollic acid affords the diuretic mercaptomerine (47). ... 

Substituted (l//,3 -quinazol>ne-2,4-diones 774, as well as the 3-unsubstituted parent compound 774 (R = H), are available by treatment of 2-[(trichloroacetyl)amino]benzamides 772 with sodium hydroxide in DMSO. The reaction proceeds via intermediate isocyanate compounds 773 which undergo ring closure to the final products <20050PP560>. 

Several reaction intermediates can be observed by varying the reaction conditions. If equimolar amounts ofbromine and hydroxide are added to acetamide (26, R = Me, Scheme 2.11), the product is N -bromoacetamide (27, R = Me). Further reaction with base gives unstable salts (28), which rearrange to isocyanates (29) reaction with water and an excess of hydroxide finally leads to the amine product (30), but in alcoholic solutions urethanes (31) are formed. 

Reaction of a/i/iyt/ro-3-hydroxy-7-methyl-2-phenylimidazo[2,l-8]thi-azolium hydroxide (452) with isocyanates in boiling benzene readily provides the stable I I cycloadducts, hexahydro-l-methyl-6-phenyl-8-R-6,8a-epithioimidazo[l,2-a]pyrimidin-5,7-diones (453a-c). Structures were characterized by IR, H-NMR, C-NMR, and mass spectral data the latter indicated that all components of the reactants were retained in the adduct (79JOC3803) (Scheme 104). With maleimides, maleic anhydride, furanonitrile, DMAD, or dibenzoylacetylene, compound 452 did not yield the desired cycloadducts (454, 456,458), but gave sulfur-free compounds 455 and 457, presumably via the cycloadducts, with the elimination of H2S or elemental sulfur as illustrated in Scheme 104. 

The ethylaminocarbonyl (ethylcarbamyl, EC) derivatives of N-protected cysteine or cysteine are readily obtained by reaction with ethyl isocyanate under anhydrous conditions (Scheme 18) [231,233] pjjjg S-protection is stable toward acids such as HBr/AcOH or TFA, as well as to the standard conditions of peptide synthesis. Deprotection is achieved by treatment with 1M aqueous sodium hydroxide, hydrazine, or ammonia in methanol,or by exposure to sU-ver(I) or mercury(II) ions.t l... 

PHEMA has been effected. Reaction of p-nltro-benzenesulfonyl Isocyanate with PHEMA or copolymers containing HEMA and varying amounts of styrene followed by reduction of the nitro group with sodium dlthlonlte produced p-amlnobenzenesulfonyl carbamates of hydrogels (p-ABSC-HEMA). The precise composition of the hydrogel carbamates was determined by nonaqueous titration of the carbamate moiety with tetrabutylammonlum hydroxide In Isopropanol/dlmethylformamlde. 

Chalcones may be ring-closed to oxazinones by reaction with alkyl or aryl isocyanates in boiling benzene containing a catalytic amount of potassium hydroxide. 

ASTM El 899, Standard Test Method for Hydroxyl Groups Using Reaction with p-Toluenesulfonyl Isocyanate (TSI) and potentiometric titration with Tetrabutylammonium Hydroxide, 2002. 

Polyurethane chemolysis by reaction with ammonia or various amines has been described in the literature. Sheratte92 has proposed a process based on polyurethane decomposition by various agents. Several examples were provided for polyurethane degradation with ethanolamine (120 °C), ammonia and ammonium hydroxide (180 °C), diethylene triamine (200 °C) and other basic reagents. In all cases the process involves, simultaneously or subsequently, reaction with propylene oxide, which allows the different amines obtained to be quantitatively converted into polyols according to the reaction shown in Scheme 2.6. The polyols derived from this process were used in the reformulation of new polyurethanes by polymerization with the corresponding isocyanate, and were suitable for application in rigid foams. 

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