One-pot synthesis of symmetric 1,7-dicarbonyl compounds via a tandem radical addition–elimination–addition reaction
作者:Zhongyan Huang、Jiaxi Xu
DOI:10.1039/c3ra42932f
日期:——
A novel approach to synthesize symmetric 1,7-dicarbonyl compounds via a tandem radical additionâeliminationâaddition reaction of S-carbonylmethyl xanthates with allylmethylsulfone and its analogues has been developed. Radicals were produced from S-carbonylmethyl xanthates by adding dilauroyl peroxide and reacted with allylmethylsulfone or analogues to generate terminal olefins as intermediates. The excessive radicals reacted with the intermediate olefins immediately to give adducts of symmetric 1,7-dicarbonyl compounds. This is an efficient method to synthesize 1,7-dicarbonyl compounds under mild conditions.
A sequential carbo-formylation cascade has been developed, involving a free-radical carbo-oximation process, followed by the hydrolysis of the oxime ether. For this purpose, we designed a new SEM O-protected sulfonyl oxime, which enable both rapid radical addition and hydrolysis under mild conditions. The resulting aldehyde-esters were then engaged in various nucleophilic cascades, such as Sakurai
terminal and non-terminal alkenes such as enol esters, alkenyl sulfides, enol ethers, silyl enol ethers, enamides and enecarbamates has been developed. The reactions are carried out at room temperature under air initiation in the presence of triethylborane acting as a chain transfer reagent and 4-tert-butylcatechol (TBC) as a source of hydrogen atom. The efficacy of the reaction is best explained by very
The dilauroyl peroxide-promoted radical carboannulation of alkynoates with xanthates was developed, affording 4-aryl-3-(β-carbonyl) coumarins in moderate to good yields.
Multicomponent Radical Processes: Synthesis of Substituted Piperidinones
作者:Edouard Godineau、Yannick Landais
DOI:10.1021/ja075755l
日期:2007.10.1
Three and four-component radical and radical-organometallic processes have been developed that provide a simple access to 2,3disubstituted piperidinones. Reasonable yield and high stereoselectivities were achieved in a number of cases with three C-C bonds and one C-N bond and up to three stereogenic centers generated in one pot from readily available reagents.