Stereospecific Reactions of Nucleophilic Agents with Acetylenes and Vinyl-type Halides. IV. The Stereochemistry of Nucleophilic Additions of Thiols to Acetylenic Hydrocarbons1
The stereoselectivealkenylation of unsaturated compounds by means of a (Z)-alkenyl sulfone-titanocene(II) system is described. Treatment of alkynes and (Z)-alkenyl methyl sulfones with the titanocene(II) reagent Cp2Ti[P(OEt)3]2 produced conjugated dienes. This alkenylation system is also applicable to polar CO bonds; the simple mixing of carbonyl compounds, (Z)-alkenyl methyl sulfones, and the titanocene(II)
描述了借助于(Z)-烯基砜-噻吩并茂(II)系统的不饱和化合物的立体选择性烯基化。用钛茂(II)试剂Cp 2 Ti [P(OEt)3 ] 2处理炔烃和(Z)-烯基甲基砜可制得共轭二烯。该烯基化体系也适用于极性C O键。羰基化合物,(Z)-烯基甲基砜和钛茂(II)试剂的简单混合形成了烯丙醇。烯基化的优点是它不需要制备烯基金属试剂,并且可以完全立体选择性地进行。
E and Z methyl styryl sulfides undergo highly regioselective cycloadditions with benzo and mesitonitrile oxide. The regioselectivity is lower with sulfoxides and is reversed in the case of sulfones. The directing effect of the thio moieties has been clarified in the framework of the frontier model of cycloaddition reactions. The lower effect of the thio substituents in the cycloadditions of cyclic
Silver(I)-mediated reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides: Unexpected formation of vinyl sulfones
作者:Gui Sheng Deng、Teng Fei Sun
DOI:10.1016/j.cclet.2012.07.017
日期:2012.10
Abstract A novel reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides was performed in the presence of silver nitrate or triflate. Conjugated vinyl sulfones as dramatic products were obtained in moderate yields and with Z -selectivity. A free radical mechanism has been proposed to account for the formation of the products.
Titanocene(II)-Promoted Multicomponent Reactions Utilizing Alkynyl Sulfones, Alkenyl Sulfones, and Carbonyl Compounds: A Novel Method for the Synthesis of Vinylallenes
Titanocene(II)-promoted cross coupling of alkynyl- and (Z)-alkenyl sulfones affords alpha-(phenylsulfonyl)alkenyltitanium species. Further treatment of these species with the titanocene(II) reagent generates titanium vinylvinylidene complexes, which react with carbonyl compounds in one pot to produce substituted vinylallenes with complete stereoselectivity. By using alpha,beta-unsaturated ketones,
Titanocene(II)-promoted alkenylation of functionalized alkynes with (Z)-alkenyl sulfones proceeded with high regio- and stereoselectivity to produce functionalized dienes. Conjugated dienylcarboxylic acids and dienylphosphonic esters were obtained using acetylenic lithium carboxylates and dialkyl phosphonates as starting materials.