Enantioselective sulfa-Michael addition reaction of methyl thioglycolate to chalcones derivatives with sterically encumbered quinine squaramide organocatalyst

Asymmetric organocatalytic sulfa-Michael reactions give access to enantiomerically enriched sulfur containing adducts that can be used as valuable chiral building blocks. A variety of chalcone derivatives were allowed to react with methyl thioglycolate under optimized conditions, in the presence of a bifunctional quinine derived sterically encumbered squaramide organocatalyst, giving rise to excellent stereoselectivities, up to 99%?ee. The designed catalyst system proved to be efficient even at gram scale and under milder reaction conditions.     

A new chiral 2-sulfonylamino-2′-phosphino-1,1′-binaphthyl ligand for highly enantioselective copper-catalyzed conjugate addition of diethylzinc to benzylideneacetones

A new axially chiral phosphine-sulfonamide ligand was prepared via a chiral component (R)-2-amino-2′-diphenylphosphinyl-1,1′-binaphthyl, which was conveniently synthesized through a new route involving hydrolysis of (R)-2-cyano-2′-phosphinyl-1,1′-binaphthyl followed by Hofmann rearrangement of the amide group. The new ligand was found to be very efficient in copper-catalyzed enantioselective conjugate addition of diethylzinc to acyclic enones such as benzylideneacetones, providing very high enantioselectivity up to 99% ee.     

Free radical-promoted conjugate addition of activated bromo compounds using titanocene(III) chloride as the radical initiator

Free radical-promoted conjugate addition of activated bromo compounds to α,β-unsaturated ketones and reactive α,β-unsaturated esters has been described using titanocene(III) chloride (Cp₂TiCl) as the radical initiator. Cp₂TiCl was prepared in situ from commercially available Cp₂TiCl₂ and activated zinc dust in THF.     

Synthesis of alicyclic esters via an intramolecular conjugate addition reaction. New method for generating (Z)-vinylcopper species from 1,1-dibromoalkenes

A novel cyclization reaction of a 1,1-dibromoalkene derivative having an α,β-unsaturated ester moiety was developed. Under the influence of Me₂CuLi, the 1,1-dibromoalkene was converted into a (Z)-vinylcopper species which in turn underwent an intramolecular conjugate addition reaction with the α,β-unsaturated ester moiety. Five-, six-, and seven-membered carbocycles were constructed by the present method. The substrate having an epoxide moiety also afforded a five-membered product via a 5-exo type intramolecular cyclization reaction.     

聚合介质酸度对聚苯胺的结构和性能的影响

不论电化学还是化学聚合,酸度对聚苯胺(PAn)的合成都有很大影响,说明只有在酸性条件下才能合成电活性的聚苯胺,鉴于聚合介质的酸度对聚苯胺的影响尚无详细的报道,本文研究了聚合介质酸度对聚苯胺的结构和性能的影响.     

Asymmetric conjugate additions of α-substituted-α-cyanoacetates to acetylenic ketones by chiral phase transfer catalysis

Asymmetric conjugate addition of α-substituted-α-cyanoacetates to acetylenic ketones has been achieved with high enantioselectivity and moderate E/Z selectivity under the influence of our recently designed, binaphthyl-modified 3,5-bis[3,5-bis(trifluoromethyl)phenyl]phenyl substituted phase transfer catalyst.     

Synthesis of the substituted spiro segment of halichlorine--use of radical cyclization and stereospecific cuprate addition to an α,β-unsaturated lactam

Radical cyclization (26a,b → 27a,b+28) and cuprate addition (28 → 31) were used as key steps to construct the spiro core 4 of halichlorine.     

Copper(I) iodide dimethyl sulfide catalyzed 1,4-addition of alkenyl groups from alkenyl-alkylzincate reagents

The presence of catalytic quantities of the copper(I) iodide dimethyl sulfide complex {(CuI)₄(SMe₂)₃} with alkenyl-alkylzincate reagents allows for the complete chemoselective 1,4-addition of various alkenyl groups to a number of α,β-unsaturated carbonyl compounds in CH₂Cl₂ at +35 °C. The 1,4-addition of the mixed vinylzincate reagent is more efficient than the corresponding vinylzirconocene reagent in CH₂Cl₂ or THF. By employing CH₂Cl₂ as a medium, the asymmetric copper-catalyzed addition of the vinyl groups to α,β-unsaturated imides is facilitated by the presence of TMSOTf to give excellent yields and up to 95:5 diastereomeric ratios (dr).     

Synthesis of novel highly water-soluble 2:1 cyclodextrin/fullerene conjugates involving the secondary rim of β-cyclodextrin

Two novel fullerene[60]-cyclodextrin conjugates have been prepared, they display the highest solubility in water reported to date. This is the first synthesis of such conjugates in which the linker is attached to the secondary rim of β-CD.     

Highly efficient phosphine-catalyzed aza-Michael reactions of α,β-unsaturated compounds with carbamates in the presence of TMSCl

Aza-Michael reactions of enones with carbamates took place efficiently in the presence of a catalytic amount of phosphine and TMSCl to afford the total products in high yields. The new catalytic system was also efficient in the aza-Michael reaction of chalcone, which was difficult to react with carbamates by transition metal salts catalysts.