氯化钯催化的交叉偶联反应

钯催化的交叉偶联反应已经成为有机合成化学中构建C-C键最重要的方法之一.其中,氯化钯及其配合物所组成的催化体系具有高效、高选择性、稳定以及价廉等优点,因而在交叉偶联反应中得到较为广泛的应用.综述了氯化钯及其配合物催化的交叉偶联反应,其中包括Suzuki反应、Stille反应、Hiyama反应和Kumada反应等.     

Reactions of 2-hydroxybenzonitrile with isocyanates

Triethylamine catalyzes the reaction of 2-hydroxybenzonitrile ( 1 ) with aryl isocyanates to form the corresponding carbamates 2a-c , as well as the cyclization of the latter compounds to either 4[N-(N-arylcarbamoyl)-imino]-3-aryl-2H-1,3-benzoxazin-2-ones 4a-c , or 4-arylamino-2H-1,3-benzoxazin-2-ones 7a-c , depending on the reaction temperature. Under analogous conditions, the carbamates obtained from 1 and 2-chloroethyl isocyanate, 3-chloropropyl isocyanate and ethyl isocyanatoacetate undergo a double cyclization yielding imidazo- and pyrimido[1,2-c|1,3]benzoxazinones 13a,b,17 . Upon heating in phenyl ether, compounds 7a-c , rearrange to 2-(2-hydroxyphenyl)-4(3H)-quinazolinones 10a-c .     

2-Aminoethanols in Transacetalization Reactions

Symmetric and mixed nitrogen-containing acetals and enol ethers were synthesized in an overall yield of 46-63% by reactions of N,N-dialkylaminoethanols with diethyl acetals derived from cyclohexanone, cyclopentanone, and acetophenone.     

Reactions of 2-acyl-1,3-indandiones

2-Pivaloyl-1,3-indandione reacts with thiosemicarbazide in aqueous base, through two successive retro-Claisen reactions, to yield 1-hydroxy-4-methylphthalazine. The mechanism of this reaction is described. Under similar conditions, 2-benzoyl and 2-acetyl-1,3-indandione, did not undergo the same reaction, a steric factor is considered.     

Reactions of 2-arylhydrazonoacetamidoximes with orthoesters

The reactions of 2-arylhydrazono-2-carbamoylacetamidoximes with orthoesters afford either 3-arylhydrazono-1,2,4-oxadiazoles or 1,2,3-triazoles, depending on the reactant structure.     

Reactions of 2-amino- and 2-hydrazinobenzimidazoles with 2-acyldimedones

The reaction of 2 formyldimedone with 2-amino- and 2-hydrazinobenzimidazoles at 20°C in ethanol gave 2-(2-benzimidazolyl)aminomethylene- and 2-[2-(2-benzimidazolyl)hydrazinomethylene]-5,5-dimethylcylohex-anediones, while this reaction carried out in ethanol at reflux in the presence of acid gave 2,2-dimethyl-4-oxo 1, 2, 3, 4-tetrahydroquinazolino(1, 2-a]benzimidazole and 1-(2-benzimidazolyl)-6, 6-dimethyl-4-oxo-4, S, 6, 7-tetrahydroindazole, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 247–252, February, 1996.     

Reactions of thiolate anions with 2-substituted-2-nitropropanes

Thiolates undergo substitution reactions with 2-substituted-2-nitropropanes by an S_RN1 mechanism or are oxidised to disulphides by an ionic mechanism.     

Reactions of 2-polyfluoroacylcyclohexanones with 1,2-diaminoarenes

Reactions of 2-polyfluoroacylcyclohexanones with 1,2-diaminoarenes yield, depending on the reaction conditions, various 2-polyfluoroalkyl-substituted benzimidazoles. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 562–565, March, 1999.     

Reactions of 2-aminopyridines with phosphorus pentachloride

The reaction of 2-aminopyridines with PCl₅ proceeds with the formation of 2-trichlorophosphazopyridines, which when treated with morpholine are converted to 2-dimorpholidochlorophosphazopyridines. By heating these last products with 96% ethanol, dimorpholido pyridyl-2-amidophosphoric acids are obtained.     

Reactions of 2-aminopyridine with picryl halides

2-Aminopyridine reacts with picryl halides to give mixtures of 1-picryl-2-(N-picrylimino)-1,2-dihydropyridine and 2-(N-picrylamino)pyridine. When picryl fluoride is treated with an excess of 2-aminopyridine, the 1-picryl-2-(N-picrylimino)-1,2-dihydropyridine reacts further with 2-aminopyridine to yield two molecules of 2-(N-picrylamino)pyridine in a reaction catalyzed by the by-product, hydrogen fluoride. In contrast, the compositions of the mixtures obtained from the reactions of picryl chloride and picryl bromide with excess 2-aminopyridine are stable in their reaction media.     

Reactions of fluorinated silanes with 2-nitrocinnamates

The interaction of 2-nitrocinnamates with silicon reagents Me₃SiR_f (R_f = CF₃, C₂F₅, and C₆F₅) promoted either by sodium acetate in DMF or by tetrabutylammonium acetate in dichloromethane has been described. The reactions proceed as conjugate addition of fluorinated carbanion at the CC bond and afford 3-aryl-2-nitrobutanoates bearing a fluorinated substituent in good yields as diastereomeric mixtures in ratio from 1:1 to 1.6:1.     

Reactions of 2-aminothiophenol with pyridineand imidazolecarboxaldehydes

Russian Chemical Bulletin - Reflux of imidazole-2-carboxaldehyde, 1-methylimidazole-2-carboxaldehyde, imidazole4-carboxaldehyde, or 5-bromopyridine-2-carboxaldehyde with 2-aminothiophenol in...     

Reactions of 2-arylaminobenzo-thiazoles with methyl acrylate

Addition of 2-arylaminobenzothiazoles to the C=C bond of methyl acrylate gives a mixture of isomeric 2-arylimino-3-(β-carbomethoxyethyl)benzothiazolines and 2-[N-aryl-N-(β-carbomethoxyethyl)amino]-benzothiazoles. Their thermal stability was studied, HPLC analysis was used to follow the dynamics of the accumulation of the compounds formed in the reaction mixtures. Institute for the Chemistry of Plant Materials, Uzbekistan Republic Academy of Sciences, Taskhkent 700170. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1428–1431, October, 1999.     

Reactions of 2-hydroxybenzophenones with Corey-Chaykovsky reagent

A variety of 2-hydroxybenzophenones on reaction with Corey-Chaykovsky reagent underwent unprecedented rearrangements leading to 3-substituted benzofurans 8 and one-carbon homologated compounds 9 and 12. Compounds 9 could further be quantitatively transformed to 2-substituted benzofuran derivatives 10.