highly active hydrogenation catalysts for carbonylcompounds, starting with neutral Rh(I) hydride complexes, [RhH(PR3)n] (R=i-Pr, n=3; R=Cy, n=2), has led to the discovery of cationic Rh(I) complexes with fully alkylated diphosphine ligands, [Rh(i-Pr)2P(CH2)nP(i-Pr)2}(NBD)]Cl04 (n=3,4). These compounds prove to be versatile and efficient for hydrogenation of a variety of carbonylcompounds, including
Photochemical Acetalization of Carbonyl Compounds in Protic Media Using an in Situ Generated Photocatalyst
作者:H. J. Peter de Lijser、Natalie Ann Rangel
DOI:10.1021/jo0485886
日期:2004.11.1
Carbonylcompounds are conveniently converted into their corresponding dimethyl acetals in good yields and short reaction times by means of a photochemical reaction in methanol with a catalytic amount of chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone, CA) as the sensitizer. Using aldehydes gives better results than using ketones, which also tend to form enol ethers as side products. These results
Elimination−Addition Mechanism for Nucleophilic Substitution Reaction of Cyclohexenyl Iodonium Salts and Regioselectivity of Nucleophilic Addition to the Cyclohexyne Intermediate
intermediate. The cyclohexyne formation was confirmed by deuterium labeling and trapping to lead to [4 + 2] cycloadducts and a platinum-cyclohexyne complex. Cyclohexyne can also be generated in the presence of some other mild bases such as fluoride ion, alkoxides, and amines, though amines are less effective bases for the elimination. Kinetic deuterium isotope effects show that the anionic bases induce the E2
Reaction of Enol Ethers with the I2-H2O2 System: Synthesis of 2-Iodo-1-methoxy Hydroperoxides and Their Deperoxidation and Demethoxylation to 2-Iodo Ketones
The reaction of enol ethers with the I2-H2O2 system in diethyl ether affords 2-iodo ketones and the previously unknown 2-iodo-1-methoxy hydroperoxides. In the presence of the I2-H2O2 system, the latter compounds undergo deperoxidation and demethoxylation to form 2-iodo ketones. The reaction conditions were found for the synthesis of 2-iodo ketones from enol ethers in 67-94% yields.