Benzyl isocyanate, reaction with

A first terminal imido complex of nickel (121) was prepared according to Equation (3).468 The synthesis goes via the Ni11 amido compound (122) and uses the steric bulk of the arylimido group for stabilization. The Ni11 center in (121) is planar and three-coordinate. Reaction of (121) with CO or benzyl isocyanide leads to formal nitrene transfer with formation of (124) and (125), respectively. Further reaction with CO liberates the isocyanate and carbodiimide (Equation (4)). 69... 

The reaction of pentafluorophenyl isocyanate with thiadiazole 8 in acetonitrile at room temperature gave 5-penta-fluorophenylureido-l,3,4-thiadiazole-2-sulfonamide 105 (Equation 31) <2004JME2796>. Similarly, 2-amino-l,3,4-thia-diazole 37 reacts with benzyl isocyanate in dry THF to afford the l,3,4-thiadiazol-2-yl urea 106 in 94% yield (Equation 32) <1999JME1525>. 

In the reaction of the conformationally restricted epoxy alcohol 84 and methyl or benzyl isocyanate, the epoxy carbamate 85 was formed. Cycliza-tion of 85 in tetrahydrofuran in the presence of sodium hydride gave the oxazinone 86 in approximately 20% yield, and the oxazolidinone 87 (R = Me, CH2Ph) in 40-60% yield. The formation of the two products can be rationalized by different nucleophilic attacks on the urethane nitrogen. With increasing nucleophilicity of the nitrogen, the regioselectivity of the reaction is shifted toward the formation of 87 (92TL3009). 

Takatsuki and co-workers have recently introduced the 3, 5 -0-sulfinyl group which has the dual purpose of protection and activation in nucleoside chemistry. For example, compound 13, prepared by protection of 12 as shown in Scheme 3, underwent reaction with benzyl isocyanate followed by intramolecular displacement of the sulfmate to give the product 14 <2004TL137>. A similar approach has also been used to prepare thioglycoside epoxides <2004CAR2895>. 

The synthesis of the pyrimidine ring represents a well-studied group of heterocyclization reactions based on enamines. One of the important approaches involves the reaction of enamines with assorted isocyanates and isothiocyanates. Thus, a reaction of enaminonitriles with benzyl isocyanate or phenyl isocyanate gives C- and N-adducts (190a and 190b, respectively) or their mixtures, which are transformed in a single step into 4-pyrimidinone (191) and 2-pyrimidinone (192) derivatives (94JHC329). The... 

The first step in the overall synthetic scheme (Scheme 6) is the condensation of an appropriate carboxylic acid with trifluoroacetaldehyde. The carboxylic acid is chosen to impart specificity for the target enzyme. In one example,[28 the dianion of cyclohexanepropanoic acid (29) was formed by the addition of LDA and then quickly condensed with trifluoroacetaldehyde to form the p-hydroxy acid 30 as a racemic mixture of erythro- and threo-isomers. The p-hydroxy acid 30 is then protected with TBDMSOTf forming 31. Diphenyl phosphorazidate, TEA, and benzyl alcohol were then utilized in a Curtius rearrangement of the protected alcohol 31, which proceeds through an isocyanate intermediate that yields the protected amino alcohol 32 upon reaction with benzyl alcohol. In order for this step to occur at an appreciable rate, a second equivalent of triethylamine had to be added. The amino alcohol 32 was then deprotected and coupled with Boc-Phe-Leu-OH to give the trifluoromethyl alcohol 33, which was oxidized to the corresponding trifluoromethyl ketone 34 as a 1 1.2 mixture of diastereomers using the Dess-Martin periodinane procedure. Thus far, the compound shown in Scheme 6 is the only compound that has been synthesized by this method, but it is reasonable to assume that many other similar fluoro ketones can be produced by this scheme. 

Several new complexes of iminophosphoranes have been reported by Cavell and co-workers (Scheme 9). Reaction of dimethyl zinc with bis- trimethylsilyl-imino-diphenylphosphorano methane (61) yields zinc complex (62) via elimination of methane. Complex (62) did not react with adamantyl nitrile or isonitrile but does undergo nucleophilic addition reactions with hetereroallenes such as carbodiimides and isocyanates. Thus, treatment of (62) with adamantyl isocyanate produces the novel tripodal alkyl zinc complex (63). Iminophos-phorane (61) reacts with [Sm(NCy2)3(THF)] and tetrakis(benzyl)zirconium(IV)... 

The reactivity of the model phenols and benzyl alcohols with phenyl isocyanate was determined in the presence of a tertiary amine (DMCHA) and a tin catalyst (DBTDL) by measurement of the reaction kinetics. The experimental results based on initial equal concentrations of phenyl isocyanate and protic reactants showed that the catalyzed reactions followed second order reaction with respect to the disappearance of isocyanate groups (see Figure 1). It was also found that a linear relationship exists between the experimental rate constant kexp, and the initial concentration of the amine catalyst (see Figure 2). In the case of the tin catalyst, the reaction with respect to catalyst concentration was found to be one-half order (see Figures 3-4). A similar relationship for the tin catalyzed urethane reaction was found by Borkent... 

The effect of type of catalyst on the reactivity of phenol and benzyl alcohol with phenyl isocyanate can be seen in Table III. In the case of tertiary amine (DMCHA), there is a relatively small difference in the reactivity of both the phenol and benzyl alcohol with phenyl isocyanate. Using DBTDL as catalyst, benzyl alcohol was found to be 26 times more reactive than phenol in the reaction with phenyl isocyanate. 

Scheme 9.3 Reaction of NBDPZ (10) with propyl isocyanate (11), benzyl isocyanate (12) and toluene-2,4-diisocyanate (13) to give the corresponding NBDPZ-urea derivatives (14).

BENZYL AMINE (100-46-9) A strongly alkaline liquid. Incompatible with strong acids, organic anhydrides, isocyanates, aldehydes, alkylene oxides, epichlorohydrin, aldehydes, alcohols, glycols, phenols, cresols, caprolactum solution. Violent or explosive reaction with Al-chlorosuccinimide. Slowly corrodes some metals. Attacks some plastics, rubber, and coatings. 

BENZYLCARBONYL CHLORIDE (501-53-1) Combustible liquid (flash point 176°F/80°C oc). Vigorous decomposition occurs at these temperatures thus, these values are anomalous due to the effect of the decomposition products (benzyl chloride and carbon dioxide). Reacts with water, producing hydrochloric acid. Violent reaction with strong oxidizers, bases. Incompatible with strong acids, nitrates. The aqueous solution is incompatible with sulfuric acid, alkalis, ammonia, aliphatic amines, alkanolamines, alkylene oxides, amides, epichlorohydrin, organic anhydrides, isocyanates, nitromethane, vinyl acetate. Attacks metals in the presence of moisture. 

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