From Unsaturated Isocyanates

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

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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). 

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] ... 

Simple addition, in which both fragments of the NH molecule enter the new compound as in the preparation of alkanolamines from alkylene oxides, aminonitriles from unsaturated nitriles, and ureas and thioureas from isocyanates and isothiocyanates. 

Synthesis of yd-Lactams from Unsaturated Sugars and Isocyanates... 

W. J. McKillip and C. N. Impola, Compositions made from (A) Isocyanate-Terminated Prepolymers and (B) Polyesters Prepared from Polyols and a, Ethylenically Unsaturated Monocarboxylic Acids, U.S. Pat. 3,396,210 (1968). IPN-type compositions. P. Mendoyanis, Thermosetting Compositions Containing a Liquid Rubber Selected from Polysulfide, Polymercaptan, and Chlorinated Polyethylene. Together with an Epoxide and Curing Agent, U.S. Pat. 3,316,324 (1967). SIN compositions of epoxy and polysulfide rubber. 

From Unsaturated Sugars. — Allylic rearrangement of ally cyanates, formed in situ from carbamates such as 24 (derived originally from o-glucal triacetate), yielded isocyanates, e.g. 25, that could then be converted to allylic amine derivatives, e.g. 26 (Scheme 6). Trapping of an allylic... 

Pd-cataly2ed reactions of butadiene are different from those catalyzed by other transition metal complexes. Unlike Ni(0) catalysts, neither the well known cyclodimerization nor cyclotrimerization to form COD or CDT[1,2] takes place with Pd(0) catalysts. Pd(0) complexes catalyze two important reactions of conjugated dienes[3,4]. The first type is linear dimerization. The most characteristic and useful reaction of butadiene catalyzed by Pd(0) is dimerization with incorporation of nucleophiles. The bis-rr-allylpalladium complex 3 is believed to be an intermediate of 1,3,7-octatriene (7j and telomers 5 and 6[5,6]. The complex 3 is the resonance form of 2,5-divinylpalladacyclopentane (1) and pallada-3,7-cyclononadiene (2) formed by the oxidative cyclization of butadiene. The second reaction characteristic of Pd is the co-cyclization of butadiene with C = 0 bonds of aldehydes[7-9] and CO jlO] and C = N bonds of Schiff bases[ll] and isocyanate[12] to form the six-membered heterocyclic compounds 9 with two vinyl groups. The cyclization is explained by the insertion of these unsaturated bonds into the complex 1 to generate 8 and its reductive elimination to give 9. 

Several approaches to the 1,2,3-triazole core have been published in 2000. Iodobenzene diacetate-mediated oxidation of hydrazones 152 led to fused 1,2,3-triazoloheterocycles 153 <00SC417>. Treatment of oxazolone 154 with iso-pentyl nitrite in the presence of acetic acid gave 1,2,3-triazole 155, a precursor to 3-(W-l,2,3-triazolyl)-substituted a,P-unsaturated a amino acid derivatives <00SC2863>. Aroyl-substituted ketene aminals 156 reacted with aryl azides to provide polysubstituted 1,23-triazoles 157 <00HC387>. 2-Aryl-2T/,4/f-imidazo[43-d][l,2,3]triazoles 159 were prepared from the reaction of triethyl AM-ethyl-2-methyl-4-nitro-l//-imidazol-5-yl phosphoramidate (158) with aryl isocyanates <00TL9889>. 

The hydrogenation step following hydroformylation serves two important purposes. It reduces the aldehyde intermediate product to the desired primary alcohol functional group, which is the primary site of reactivity of the polyol with isocyanates. It also reduces the residual olefins in the FAMEs to saturated hydrocarbons, thus eliminating the pathway to Hock degradation and odor development, which is inherent to other processes that leave fatty acid unsaturation in the polyols. This step eliminates the typical vegetable oil odor from the final namral oil polyols of this process. 

Vinyl isocyanates, readily available from the corresponding a,/3-unsaturated acids by a Curtius procedure, have been by far the systems studied in more detail, mainly by the Rigby group, e.g., in the construction of the pyridone ring (Scheme 53). Thus, heteropolycyclic compounds having 2-pyridone structure 233 were shown to be formed in moderate to... 

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