To demonstrate the utility of isocyanides in catalytic C−H bond functionalization reactions, a palladium-catalyzed cyclocoupling reaction of 2-halobiaryls with isocyanides was developed. The reaction afforded an array of fluorenone imine derivatives via the cleavage of a C−H bond at the 2′-position of 2-halobiaryls. The use of 2,6-disubstituted phenyl isocyanide was crucial for this catalytic cyclocoupling reaction to proceed. The reaction was applicable to heterocyclic and vinylic substrates, allowing the construction of a wide range of ring system. The large kinetic isotope effect observed (k
H/k
D = 5.3) indicates that C−H bond activation was the turnover-limiting step in this catalysis.
The insertion reaction of isocyanide into a C-S bond of dithioacetals is catalyzed by GaCl3 or TiCl4 to afford thioimidates containing an alpha-alkylthio group. Balanced thiophilicity of these Lewis acids is critical for efficient catalysis.
Quantitative analysis of nitrilotriacetate (NTA) in detergents by titration with Cu 2+ solution using a copper ion selective electrode was achieved. This method tolerates a wide range of pH and ingredients in detergents. In addition to NTA, other chelating agents, having relatively lower stability constants toward Cu 2+ , were also qualified with sufficient accuracy by this analytical method for model detergent formulations. The titration process was automated by automatic titrating systems available commercially.
Bonds. -The process provides a new and efficient approach to fluorenone imine derivatives and the nature of the isocyanide has a strong influence on the success. This method can be applied to prepare various heterocyclic analogues like (X) and (XII) and some indenone imine derivatives such as (XVI). -(TOBISU, M.; IMOTO, S.; ITO, S.; CHATANI*, N.; J.
Thio compounds Q 0590GaCl3-and TiCl4-Catalyzed Insertion of Isocyanides into a C-S Bond of Dithioacetals. -Dithioacetals (I) require slow addition of isocyanide (II) to avoid formation of double-insertion products. Comparable yields are obtained with GaCl3 and TiCl4. Substrates (IV) bearing aromatic substituents afford exclusively mono-insertion products, even if the isocyanide is added all at once. The same effect is observed for mixed O,S-acetals (VI), where the insertion occurs only at the C-S bond. The thioimidates can be hydrolyzed under acidic conditions into thioesters as useful building blocks for organosulfur compounds. -(TOBISU, M.; ITO, S.; KITAJIMA, A.; CHATANI*, N.; Org. Lett. 10 (2008) 22, 5223-5225; Dep. Appl. Chem., Fac. Eng., Osaka Univ., Suita, Osaka 565, Japan; Eng.) -R. Simon 15-084
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