Unsaturation isocyanates

Insertion of unsaturated isocyanates into the M—O bond of M(OR)5 has been reported6,204,205 to give mono- to penta-substituted products (equation 4). No insertion into the Nb—O bond was observed with phenyl isothiocyanate. 

Dielectrophilic species are 1,4-diketones, certain 1,3-dienes, a,B-unsaturated isocyanates, isothiocyanates, cyanates, and thiocyanates bearing electron-withdrawing (e.g., polyfluorinated and perfluorinated) substituents the most frequently used 1,1-dinucleophiles are water, potassium sulfide, primary amines, and ammonia. From this repertoire of building blocks many combinations are possible. Tetrakis(trifluoro-methyl)furans, thiophenes, and pyrroles have been synthesized from per-fluoro-3,4-dimethylhexa-2,4-diene on addition of water, potassium sulfide, or aniline (90CC1127) (Scheme 39). 

Unsaturated isocyanates 3 are converted into bis-unsaturated carbodiimides 4 using a phos-pholene oxide catalyst. ... 

Condensation of RR CHCHO (R = H or alkyl R = H, alkyl, CH2=CH, Ph or PhCHj) with Me3CNHj, followed by the reaction of the resultant aldimine with phosgene and thermal elimination of Me3CCl and HCl from the acid chloride, gave a, 3-unsaturated isocyanates [1150a] ... 

Nitriles react with phosgene only in the presence of hydrogen chloride, to give either 1,2-unsaturated isocyanates or N-heterocyclic derivatives. The reactions are really those between COClj and the imidoyl chlorides or 1-chloroenamines, since these are the materials formed, reversibly, as equilibrium mixtures when hydrogen chloride adds to nitriles [2229] ... 

With hydrogen chloride in a benzene solution, phosgene combines with CHjClCHjCN, CHjClCHClCN, MejCHCN or MeCH(CHjCl)CN to form the corresponding cis- and trans-isomers of 1-chloro-1,2-unsaturated isocyanates, along with pyrimidine derivatives [1543] ... 

A very convenient method to obtain a macromer (structure 6.13) is by using an unsaturated isocyanate [50] or by using some accessible raw materials, by the reaction of a hydroxy alkyl acrylate or methacrylate with one -NCO group of a diisocyanate for example, 2,4 toluene diisocyanate (TDI) and to react the remaining -NCO group with the terminal hydroxyl group of a polyether polyol ... 

Owing to the highly unsaturated isocyanate functional group, methyl isocyanate exhibits high reactivity. It decomposes with water and reacts vigorously with acids, bases, amines, and metals and their salts. 

The most widely documented aspect of phosgene chemistry is the interaction of the reagent with nitrogen nucleophiles (for example, R3N). The intermediate complex 129 formed is unstable and usually collapses, with elimination of RCl, to give a stable carbamoyl chloride derivative 130. The carbamoyl chloride thus formed can eliminate RCl to create a new site of unsaturation (isocyanate, 131) and/or react further with another molecule of starting material to afford urea, 132, a tri-coordinated carbonic acid derivative (see Scheme 4.1). 

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