1.2- Diketones reaction with isocyanates

Kuninobu has found that benzaldimines undergo C-H activation and acetylene insertion to give indenes using a rhenium catalyst (Equation (43)). A similar reaction with isocyanates gives rise to phthalimidine derivatives (Equation (44)). " This catalyst also efficiently permits insertion of terminal alkynes into the acidic C-H bond of 1,3-diketones to give branched vinyl products. 

Reaction of lithiated 3-enaminophosphonj tes of aniline and isocyanates with subsequent cyclization of the resulting amides with triphenylphosphine/triethylamine leads to the 3-phosphonyl-4-aminoquinolines (Equation 92) <1999T5947>. Aniline reaction with /3-diketones < 1999H(51 )2171 > and ethoxymethylenemalonates <1999JFC(94)7> also leads to quinoline formation. The Vilsmeier reaction conditions can also be applied to the synthesis of quinolines with the use of a-oxoketene /V -anilinoacetals (Equation 93) <2003JOC3966>. 

A metalloid template has been used in the synthesis of some triazepinones and triazepinethiones thus, for example, the reaction of acyclic diamines with dimethylsilicon isocyanate gave (212) after its reaction with thiocarbonyl diimidazole and subsequent hydrolytic removal of the silicon template, (212) gave (213)/ Aminohydroxy-l,2,4-triazepines (214 R = H or Me) have been prepared in high yield by the addition of aminoguanidine to acrylonitrile and related unsaturated esters.Condensation of )8-keto-esters with 1,2-diamino-imidazoles gave mainly imidazotriazepinones, e.g. (215), but with jS-diketones O... 

Another example of a multistep synthesis using only PSQ purification procedures was described by Hodges etal. In the first step, 1,3-diketone 47 was reacted with an excess of hydrazine 48 in the presence of morpholinomethyl-polystyrene (49). Removal of excess 48 by quenching with polymer-bound isocyanate 50 afforded pyrazole 51 with a purity of 97% (HPLC) but in quite moderate yield (48%). In the second step, 51 was converted into a mixed anhydride (by treatment with isobutyl chloroformate in the presence of 49) and subsequently transformed in situ into 5 3 by reaction with an amine. Addition of the polymer-bound reagents 50 and 52 removed excesses of chloroformate and amine by filtration and 53 was isolated in 75% yield with a purity of 97% (HPLC). 

Zirconium and hafnium tetraalkoxides are highly reactive compounds. They react with water, alcohols, silanols, hydrogen halides, acetyl halides, certain Lewis bases, aryl isocyanates and other metal alkoxides. With chelating hydroxylic compounds HL, such as j8-diketones, carboxylic acids and Schiff bases, they give complexes of the type ML (OR)4 these reactions are discussed in the sections dealing with the chelating ligand. 

Diaryl-1,2,3,5-oxathiadiazines (277 from sulfur trioxide and aryl isocyanates) with (3-diketones yield pyrimidines (278). s-Triazine reacts with RCH2CN to give 4-aminopyrimidines (279 see Section 3.2.1.6.1 for a similar reaction), and with electron-rich alkenes and alkynes to yield pyrimidines such as (280) from EtC = CMe (Section 3.2.1.10.2). 

Catalytic hydrogenation of the trimethyl phosphite-a-diketone adducts (76) gives the ketones (77) essentially quantitatively. The dioxaphospholan (78), obtained from the trimethyl phosphite-biacetyl adduct and isopropylidene-D-glyceraldehyde, has been converted into isomeric glycosides of l-deoxy-3-C-methyl-D-r/6o-hexulose. Another account has appeared of the reactions of (76) with aroyl and sulphonyl isocyanates."... 

We begin with reactions of polar organometallics with aldehydes, ketones, and v/c-dicarbonyl compounds (a-oxoaldehydes, 1,2-diketones, a-oxocarboxamides, and a-oxocarboxylic acids). Next we focus on carboxamides, lithium carboxylates, carboxylic acid esters, and acyl chlorides. Finally we turn to ketenes, (thio)isocyanates, and carbon dioxide, all featuring cumulated double bonds, and last but not least to carbon monoxide. 

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