Selenium-mediated conversion of alkynes into .alpha.-dicarbonyl compounds
摘要:
The reaction of terminal and internal alkynes with diphenyl diselenide and ammonium peroxydisulfate in methanol proceeds smoothly to give alpha-keto acetals and alpha-keto ketals, respectively. This one-pot procedure is suggested to proceed through the initial formation of phenylselenenyl sulfate, a strong electrophilic reagent which effects the methoxyselenenylation of the alkynes. The addition products thus formed suffer methoxydeselenenylation giving the observed products and regenerating the phenylselenenylating agent. In some cases the reaction can be carried out using only catalytic amounts of diphenyl diselenide. The same reaction carried out in the presence of water or of ethylene glycol gives the unprotected or the diprotected alpha-dicarbonyl compounds, respectively.
A switchable and benign protocol for chemoselectivesynthesis of sulfoxides and α-alkoxy-β-ketothioethers has been developed. It was determined that various thiophenols and alkenes/alkynes are compatible to realize the target compounds from a medium to a high yield by regulating the reaction temperature. In particular, methanol not only served as a solvent but also participated in the reaction process
Photoinduced Alcoholysis of α,α,α-Tribromoacetophenone to Benzoylformate
作者:Yasuji Izawa、Katsuhiro Ishiguro、Hideo Tomioka
DOI:10.1246/bcsj.56.1490
日期:1983.5
Irradiation of p-substituted α,α,α-tribromoacetophenones (1) in O2-saturated alcohols (MeOH, prim. and sec. alcohols) afforded a new alcoholysis product, benzoylformate (2), in good yield (75–85%) along with benzoate and radical (reduction) products. Sensitization experiments showed that 2 was derived from the triplet excited 1. Formation of 2 as well as the decomposition rate of 1 were greatly accelerated
An acrylic ester compound represented by the general formula (1):
1
wherein, R
1
and R
2
represent independently a hydrogen atom, an alkyl group which may have a substituent, an aromatic alkyl group which may have a substituent or an aromatic residue which may have a substituent, respectively; R
3
represents a hydrogen atom or an alkyl group; A represents a divalent organic group; and X represents a sulfur atom or an oxygen atom; provided that when X is an oxygen atom, R
1
represents an aromatic residue that may have a substituent, a polymerizable composition comprising the compound, and a cured article and optical components obtained by polymerizing the polymerizable composition.
An article that includes a functionalized copolymer and the use thereof, particularly in a process for binding biomaterials, such as in a process for separating aggregated proteins from monomeric proteins in a biological solution; wherein the article includes: a) a porous substrate; and b) a copolymer covalently attached to the porous substrate, the copolymer comprising a hydrocarbon backbone and a plurality of pendant groups attached to the hydrocarbon backbone, wherein 1) each of a first plurality of pendant groups comprises: (a) at least one acidic group or salt thereof; and (b) a spacer group that directly links the at least one acidic group or salt thereof to the hydrocarbon backbone by a chain of at least 6 catenated atoms; and 2) each of a second plurality of pendant groups comprises: (a) at least one acidic group or salt thereof; and (b) a spacer group that directly links the at least one acidic group or salt thereof to the hydrocarbon backbone by a chain of at least 6 catenated atoms; and wherein the first plurality of pendant groups are different than the second plurality of pendant groups; and wherein a mole ratio of the first plurality of pendant groups to the second plurality of pendant groups is in a range of 95:5 to 5:95.
ruthenocene-based phosphine-oxazoline ligand tBu-mono-RuPHOX or the diphosphine ligand BINAP, were developed for the asymmetrichydrogenation of 5,6-dihydropyrazin-2(1H)-ones, affording chiral piperazin-2-ones in good yields and with moderate to good ees. Different catalytic behaviors for the hydrogenation of these types of substrate were observed with these two catalyst systems. Our tBu-mono-RuPHOX ligand, which