Mesityl isocyanate

Acylnitrenes are formed by photolysis of acyl azides and react intramolec-ularly to form lactams.149 154 Evidence was adduced that it is a singlet nitrene which cyclizes to the lactam 108 on photolysis of the sulfilimine 107.155 Thermolysis gave only mesityl isocyanate (109).155 Isocyanates often,156 but not always157 accompany photolyses of acyl azides but generally this is thought to be a nonnitrene process (see below, however). 

Tab. 4.15. Effect of the nature and concentration of the base on the generation of mesityl isocyanate 349 with B0C2O (reaction conditions and work-up according to Method A, Table 4.14) [221].

This possibility was extensively investigated in the synthesis of mesityl isocyanate 349 (Table 4.15). 

Typical procedure. Mesityl isocyanate 349 using a catalytic amount of DMAP and B0C2O [221] A solution of B0C2O (619 mg, 2.84 mmol) in acetonitrile (2 mL) was treated successively with a solution of 4-dimethylaminopyridine (33 mg, 0.27 mmol) in acetonitrile (2 mL) and a solution of 348 (365 mg, 2.7 mmol) in acetonitrile (2 mL). 

The reaction mixture was stirred vigorously for 10 min. After the addition of concentrated sulfuric acid in acetonitrile (40% solution, p = 1.03 g cm , 0.47 mL), the resulting mixture was stirred for 5 min. Water (0.47 mL) was then added, and the mixture was stirred for a further 5 min. The reaction mixture was then poured into an equal volume of water. The solution was extracted three times with hexane, and the combined hexane layers were dried over magnesium sulfate. Removal of the solvent in vacuo afforded mesityl isocyanate 349 (420 mg, 97%) as colorless crystals mp 42 °C. 

Tab. 4.16. DMAP-mediated synthesis of mesityl isocyanate (349) from mesitylamine 348 with the activated carbonates 350 as Ci building blocks (350a = B0C2O) [221].

Reactions of [Cp Ir(NR)] R = Bu 662a or 2,6-Pr 2C6H3 662b with 2,6-xylyl isocyanide [(Xyl)NG], mesityl isocyanate, and mesityl azide were studied by Danopoulos et The bridged dimers [Cp"lt(/r-NCsFl9)]2... 

Scheme 8.4 Grafting of isocyanate-telchelic poly(l, 3-di(l -mesityl)-4- [(bicyclo[2.2.1 ]hept-5-en-2-ylcarbonyl)oxy]methyl -4,5-dihydro-l H-imidazol-3-ium tetrafluoroborate) on silica and generation of the immobilized second generation Grubbs catalyst.

Indenopyrene, see Indeno[l,2,3-crf pyrene l//-Indole, see Indole Indolene, see Indoline Inexit, see Lindane Inhibisol, see 1,1,1-Trichloroethane Insecticide 497, see Dieldrin Insecticide 4049, see Malathion Insectophene, see a-Endosulfan, p-Endosulfan Intox 8, see Chlordane Inverton 245, see 2,4,5-T lodomethane, see Methyl iodide IP, see Indeno[l,2,3-crf pyrene IP3, see Isoamyl alcohol Ipaner, see 2,4-D IPE, see Isopropyl ether IPH, see Phenol Ipersan, see Trifluralin Iphanon, see Camphor Isceon 11, see Trichlorofluoromethane Isceon 122, see Dichlorodifluoromethane Iscobrome, see Methyl bromide Iscobrome D, see Ethylene dibromide Isoacetophorone, see Isophorone a-Isoamylene, see 3-Methyl-l-butene Isoamyl ethanoate, see Isoamyl acetate Isoamylhydride, see 2-Methylbutane Isoamylol, see Isoamyl alcohol Isobac, see 2,4-Dichlorophenol Isobenzofuran-l,3-dione, see Phthalic anhydride 1,3-Isobenzofurandione, see Phthalic anhydride IsoBuAc, see Isobutyl acetate IsoBuBz, see Isobutylbenzene Isobutane, see 2-Methylpropane Isobutanol, see Isobutyl alcohol Isobutene, see 2-Methylpropene Isobutenyl methyl ketone, see Mesityl oxide Isobutyl carbinol, see Isoamyl alcohol Isobutylene, see 2-Methylpropene Isobutylethylene, see 4-Methyl-l-pentene Isobutyl ketone, see Diisobutyl ketone Isobutyl methyl ketone, see 4-Methyl-2-pentanone Isobutyltrimethylmethane, see 2,2,4-Trimethylpentane Isocumene, see Propylbenzene Isocyanatomethane, see Methyl isocyanate Isocyanic acid, methyl ester, see Methyl isocyanate Isocyanic acid, methylphenylene ester, see 2,4-Toluene-diisocyanate... 

Methylhydroxybenzene, see 2-Methylphenol p-Methylhydroxybenzene, see 4-Methylphenol Methylisoamyl acetate, see sec-Hexyl acetate Methyl isobutenyl ketone, see Mesityl oxide Methylisobutylcarbinol acetate, see sec-Hexyl acetate Methyl isobutyl ketone, see 4-Methyl-2-pentanone Methyl isocyanide, see Dimethylamine, Methyl isocyanate Methyl ketone, see Acetone... 

The addition of thiobenzoyl isocyanate to norbornene and norbornadiene resulted in the thiazinones 230 (R = Ph) and 231, respectively (67CB685). The ter/-butyl- and mesityl-substituted analogs of 230 were prepared by the same method. In the case of a benzyl substituent, the derivative 232 containing an exo double bond was formed (81CB549). 

The similar addition of a mesityl-substituted isocyanate to 1-morpiiolino-cyclohexene gave the dihydrothiazinone 233, which is in ring-chain equilibrium with 234. In the attempted preparation of the rerr-butyl-substituted derivative, the tetrahydrobenzothiazinone 235 was formed by loss of morpholine (81CB549). 

The full paper describing Mori s synthesis of lineatin (296) (Vol. 4, p. 489, Ref. 263) has been published. After converting the lactone 329 to ( )-lineatin using a [2 + 2] cycloaddition, Slessor et al. followed another route from the same lactone 329, which is readily available by the Lewis acid-catalyzed addition of ketene to mesityl oxide. The route is shown in Scheme 25. In this scheme, the mixture arising from the carbene addition is not separated because, at the stage of the epoxide formation, only the major (desired) isomer 330 was isolated, the other being thermally unstable. The exo alcohols obtained in small amounts after the borohydride reduction (step h) were not isolated. To obtain the natural isomer of lineatin [( + )-(l/ ,4S,5/ ,7R)-296] the alcohol 331 was resolved with (—)-(r)-l-(l-nephthyl)ethyl isocyanate/triethylamine. The first stereospecific chiral synthesis of (+)-lineatin (296) started from D-ribonolactone (332), and is illustrated (in somewhat abbreviated form) in Scheme 26 it proceeded in 2.7% overall yield. °... 

DIACETONALCOOL (Italian) (123-42-2z) Forms explosive mixture with air above 136°F/58°C. Violent reaction with strong oxidizers. Decomposes on contact with strong acids or strong bases, forming acetone and mesityl oxide. Reacts with alkali metals, forming explosive hydrogen. Incompatible with aliphatic amines, isocyanates, acetaldehyde, benzoyl... 

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