Trimethylsilyl isocyanate

Finally, the synthesis of tnfluoroacetyl isocyanate has been redesigned such that multigram quantities ate produced easily by treatment of tnfluoroaceiyl chlonde with trimethylsilyl isocyanate [52] (equation 26)... 

The antitumour drug temozolomide 24 (R = Me) has been attracting attention and two new routes have been develqjed. One starts from 5-aminoimidazole-4-caiboxamide, whilst the other starts from 5-diazoimidazole-4-carboxamide which reacts with trimethylsilyl isocyanate to give 8-carbamoylimidazo[5,l-[Pg.272]

The silylated glycine derivative 1450 cyclizes spontaneously on heating to 85-140 °C to give the hydantoin derivative 1451 in 94% yield [20, 21]. The silylated hy-dantoin 1453 is obtained by reacting silylated N-carboxymethylglycine 1452 with trimethylsilyl isocyanate 327 and subsequent heating to 140°C [22] (Scheme 9.12). 

Related alkoxides, such as (272), and the amide (277) display a similar activity to the acetate,964 suggesting that both alkoxide and carbonate intermediates are formed during the reaction, ll NMR spectroscopy has been used to demonstrate that (334) reacts reversibly with CHO to generate an alkoxide intermediate which subsequently inserts C02. The amide complex initiates the copolymerization by first inserting C02 into the Zn—N bond and subsequent elimination of trimethylsilyl isocyanate.965... 

The first reported synthesis of hydroxyurea (24) consists of the condensation of hy-droxylamine with potassium cyanate (Scheme 7.14) [87]. Condensation of hydroxy-lamine with ethyl carbamate also gives pure hydroxyurea in good yield after recrystallization (Scheme 7.14) [88]. Nitrogen-15 labeled hydroxyurea provides a useful tool for studying the NO-producing reactions of hydroxyurea and can be prepared by the condensation of N-15 labeled hydroxylamine with either potassium cyanate or trimethylsilyl isocyanate followed by silyl group removal (Scheme 7.14) [89, 90]. Addition of hydroxylamine to alkyl or aryl isocyanates yields alkyl or aryl N-hydroxyureas (Scheme 7.14) [91, 92]. The condensation of amines with aromatic N-hydroxy carbamates also produces N-substituted N-hydroxyureas (Scheme 7.14) [93]. 

Preparation of silyl-substituted semicarbazides from the reaction of trimethylsilyl isocyanate and hydrazine or derivatives [92]. 

The esters 35 are obtained by reaction of hydrazides 34 with chloroformate esters or carbonic diesters 3 23 28 42 as previously discussed for the special case of the activated esters (see Section 10.4.2). The amides 36, on the other hand, are formed from hydrazides 34 with isocyanic acid 3,43,44 or with trimethylsilyl isocyanate 42 (Scheme 10). 

Similar electroreductive silylation of a series of unsaturated nitrogen compounds such as trimethylsilyl cyanide, cyanamide or isocyanide, bis(trimethylsilyl)carbodiimide and trimethylsilyl isocyanate provide precursors of bis(trimethylsilyl)methylamine, which is useful for organic synthesis (equations 90 and 91)115. This electrochemical method is a safer and more economical process compared with the chemical process using an alkali metal such as lithium. 

Benzo[b]thiophene Acetaldehyde Borane pyridine complex Trimethylsilyl isocyanate... 

Method A. l-Benzo[b]thien-2-yl ethyl hydroxyl amine prepared as described above, step 3 (2.0 g, 10 mmole), was refluxed for 30 minutes with trimethylsilyl isocyanate (1.65, 14.2 mmole) in dioxane (30 ml). The reaction mixture was then washed with saturated NH4CI solution, dried with MgS04, and evaporated. 

Kimura, K., K. Katada, and S. H. Bauer An Electron Diffraction Study of Trimethylsilyl Isothiocyanate and Trimethylsilyl Isocyanate. J. Amer. chem. Soc. 88, 416—420 (1966). 

Isocyanates of fluorinated compounds can readily be obtained either from trimethylsilyl isocyanate and, e.g. trifluoroacetyl chloride, with yields of isocyanate in the region of 64%. or more conveniently by Curtius degradation of fluorinated acid chlorides. ... 

Just to illustrate the real synthetic interest of these heterocyclobutadienes, it appeared that trimethylsilyl isocyanate inserts into the P-N bond of 28 leading to 38, which after hydrolysis afforded 39 in 50 % yield. Interestingly, 39 exists as a hydrogen-bonded dimer in the solid state and has a structure very similar to that of cytosine, the C(NH2) being replaced by a P(N/Pr2)2 group it could be considered as a labelled cytosine (Scheme 15). 

It is well known that halomethyleneiminium salts, often prepared in situ (see Section 2.1.2.2) react with ammonium salts, primary amines, secondary amides, urea and IV-substituted ureas to afrbrd amidinium salts, from which the free amidines can be obtained by addition of bases. > 4 Some recent results are given below. Dimethylformamide chloride and other 7V,iV-disubstituted formamide chlorides were reacted with acetanilides, chloroacetanilides, 6-aminopenam derivatives, 2-aminopyrimidine, 4-aminouracil, 2-amino-4-chloropyridazine, 2-aminothiazole, 2-aminobenzothiazole and thiobenzamides to give the amidines via the amidinium salts. In the reaction of MA -disubstituted formamide chlorides with thiobenzamides the solvent seems to be decisive for the course of the reaction. In tertiary formamides the thiobenzamides are desulfurized to nitriles, whereas in CHCI3 or CCI4 amidinium salts (296 Scheme 45) are formed. From trimethylsilyl isocyanate and the fluorinated amine (297) the /V-fluorocarbonylamidine (298) is accessible. ... 

Approaches to l,3-oxazin-2-ones (244) utilize acylchloroenamines (242), either directly by reactions with trimethylsilyl isocyanate, or in a two-step sequence in which the corresponding acyl-vinylamidines (243) are formed first by reactions with ammonia and these products are then cyclized... 

Primary amides can be obtained if trimethylsilyl isocyanate is used, since the trimethylsilyl group is removable with ammonium chloride ... 

AMIDES Boron tribromide. Boron trifluoride etherate. 6-Chloro-l-p-chlorobenzene-sulfonyloxybenzotriazole. Diethylphosphoryl cyanide. Dihalobis(triphenylphosphine)-palladium(H). Dihalobis(triphenylphosphine)paUadium(ll) complexes. Palla-dium(II) chloride. Sodium amide. Trimethylsilyl isocyanate. Triphenylphosphine ditriflate. 

This method was successfully apphed to the sterically hindered diphenylglycine methyl ester hydrochloride (entry 8) to prepare the antiepileptic dmg phenytoin 22. In this synthesis, trimethylsilyl isocyanate (TMS-NCO), a more reactive alternative to potassium cyanate was used in the first step. The decomposition of TMS-NCO... 

An ethereal soln. of trimethylsilyl isocyanate added with stirring to a soln. of startg. azirine in ether, then after a few min methanol in ether added slowly - 4-(dimethylamino)-5,5-dimethyl-3-imidazolin-2-one. Y 78%. F.e., also 4-amino-A -2-imidazolinethiones with trimethylsilyl isothiocyanate, s. I. Handke, E. Schaumann, J. Org. Chem. 53, 5298-300 (1988). 

Zileuton [i i i406-87-2], anti-inflammatoiy, antiasthmatic, 5-lipoxygenase inhibitor, 229. Phosgene or phosgene equivalents (trimethylsilyl isocyanate, diisopropyl azodi-carboxylate) have been employed to prepare the hydroxy-urea compound Zileuton [163-169]. 

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