Efficient electrocatalytic addition reactions of allyl phenyl sulfone to electron deficient alkenes

The use of tetraalkylammonium salts as electrolytes has been found to allow the formation of electrogenerated bases of especially high reactivity. Such conditions allow allyl phenyl sulfone to undergo addition to a variety of electron deficient vinyl and propenyl compounds (sulfone, ketone, nitrile, and ester). The additions are catalyzed by electrogenerated bases derived from the reactant itself, rather than via an added pro-base. The nature of the substrate molecule is seen to affect which type of product is formed, leading to an interplay between addition to 1 mol of substrate or to 2 mol of substrate. Yields of 1:1 adducts range from 6 to 81%, while yields of 1:2 adducts range from 57 to 96%.     

Catalyzed double Michael addition of anilines to vinyl sulfone

Substituted anilines and vinyl sulfone undergo a facile double Michael addition to form substituted phenylthiomorpholine dioxide, catalyzed with AlCl₃ or H₃PO₄. Scope and conditions were explored.     

Electrocatalytic reactions: anion radical cyclobutanation reactions and electrogenerated base reactions

Intermolecular anion radical [2+2] cyclobutanation reactions have been observed between vinyl sulfones and vinyl/propenyl ketones. The products are novel and formed electrocatalytically, although yields are at best modest (11-45%). Competing mechanisms are discussed. Additionally, the electrochemical reduction of vinyl alkyl sulfones in acetonitrile leads to near quantitative formation of cyanomethylation product cyano-sulfones. The single step approach has electrocatalytic factors in excess of thirty.     

Nucleophilic trifluoromethylation of conjugate acceptors via phenyl trifluoromethyl sulfone

A mild procedure for the conjugate addition of the trifluoromethyl anion to activated Michael acceptors such as arylidenemalononitriles (15 examples) and arylidene Meldrum’s acids (9 examples) using phenyl trifluoromethyl sulfone through a reductive magnesium metal mediated procedure is described. The new methodology is used to prepare befloxatone, a reversible and selective monoamine oxidase A inhibitor.     

Stereocontrolled one-pot synthesis of cycloalkane derivatives possessing a quaternary carbon using allyl phenyl sulfone

Stereocontrolled one-pot synthesis of cyclopentane derivatives possessing quaternary carbon using allyl phenyl sulfone and epoxyiodide was presented. Furthermore, application of this protocol to the synthesis of cycloalkane derivatives with different ring sizes was successful.     

Synthesis of cyclic allyl vinyl ethers using Pt(II)-catalyzed isomerization of oxo-alkynes

Several alkynyl epoxides and one alkynyl allyl alcohol were isomerized to cyclic allyl vinyl ethers (3,4-dihydro-2H-1,4-oxazines) using PtCl₂ as the catalyst. Three of these allyl vinyl ethers were converted to 2-hydroxymorpholine derivatives by hydrolysis and two were converted to piperidine derivatives by thermal Claisen rearrangement.     

Electronegativity scheme for reactions involving radical addition to vinyl monomers

The concept of the apparent electronegativity of a reaction site has been introduced. This has been used to develop a new scheme for calculating the relative rate constants of addition of radicals with different structures to vinyl monomers. The parameters of the scheme are given for 40 reagents. The results of a comparison of calculated and literature rate constants of addition are presented.Institute of Nonaqueous Solution Chemistry, Russian Academy of Sciences, 150003 Ivanovo. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2238–2245, October, 1992.     

Chemistry of vinyl sulfones. Approach to novel conformationally restricted analogues of glutamic acid

A totally different approach to conformationally restricted glutamic acid analogues is described, in which one of the acid functions is replaced by a cyclopropanol. The reactivity of cyclopropanol vinyl sulfones toward addition of lithiated Schöllkopf bislactim ether provides a facile synthesis of α-amino acid diastereoisomers. Conformational analysis of these analogues, incorporating solvation effects, and docking to a glutamate receptor model, are used to show the relevance of the conformational restrictions employed.     

Highly efficient organocatalytic asymmetric Michael addition of homoserine lactone derived cyclic imino esters to nitroolefins

An efficient stereoselective Michael addition reaction of homoserine lactone derived cyclic imino esters to nitroolefins promoted by a bis(cinchona alkaloid) (DHQD)₂AQN was achieved. This catalytic system features a wide substrate scope, furnishing the corresponding products with excellent diastereoselectivity (>95:5 dr) and good enantioselectivity (up to 87% ee) under mild conditions, and the Michael adducts could be easily transformed into highly functionalized spirocyclic γ-butyrolactone-pyrrolidines through a sequential nitro-Mannich reaction.     

Convenient synthesis of bis(indolyl)alkanes and bis(pyrrolyl)alkanes by Cu(OTf)2-catalyzed addition of indole and pyrrole to acetylenic sulfone

Sulfonyl-containing bis(indolyl)alkanes and bis(pyrrolyl)alkanes were synthesized conveniently by Cu(OTf)₂-catalyzed double Michael addition of indole and pyrrole to acetylenic sulfone.     

C2-symmetrical bis(camphorsulfonamides) as chiral ligands for enantioselective addition of diethylzinc to benzaldehyde

Purpose of the research was to determine the activity of chiral bis(sulfonamide) ligands derived from camphor in the addition of diethylzinc to benzaldehyde. Chiral bis(ketosulfonamides) and bis(hydroxysulfonamides), have been synthesized in a reaction of diamines with camphorsulfonic acid chloride. Their activity in a reaction of asymmetric addition of dialkylzinc to benzaldehyde in a presence of titanium(IV) tetraisopropoxide was determined. The bis(ketosulfonamide) ligands reveal low enantioselectivity, with the ee% not exceeding 12%. The bis(hydroxysulfonamides) reveal much higher asymmetric induction in the investigated ZnEt₂ addition. The best enantiomeric excess (62%) has been observed for bis(hydroxysulfonamide) obtained from 1,3-diaminepropane. The yields of the reaction obtained after 18 h are 92–96%. Crystal structures have been solved for bis(ketosulfonamide) ligands obtained from diamines based on C₂ to C₄ chain. The (2R) configuration in the rings systems of bis(hydroxysulfonamide) containing the C₃ bridge was also determined by the crystal structure analysis. The sulfonamides have been characterized by IR, ¹H and ¹³C NMR.     

Conjugate addition of sodium methanesulfinate to vinyl pyridines and diazines for the synthesis of aliphatic sulfones

A convenient method to introduce a sulfone group to pyridines and diazines is described. This efficient method involves the conjugate addition of sodium methanesulfinate to vinyl heterocycles. This process tolerates a wide variety of functional groups and is performed in the presence of acetic or trifluoroacetic acid. A one-pot, two-step synthesis of sulfones starting from the corresponding heteroaryl halide is also described.     

Multicomponent reactions of allenes, diaryl diselenides, and nucleophiles in the presence of iodosobenzene diacetate: direct synthesis of 3-functionalized-2-arylselenyl substituted allyl derivatives

A multicomponent reaction of allenes, diaryl diselenides, and nucleophiles in the presence of iodosobenzene diacetate has been developed, providing a novel method for the preparation of synthetically useful 3-functionalized-2-arylselenyl substituted allyl derivatives.     

Regioselective reactions of sulfur, selenium and tellurium chlorides with allyl trimethyl silane

Electrophilic addition of SCl₂, SeCl₂ and SeCl₄ to 2 equivalents of allyl trimethyl silane proceeds regioselectively to give bis[2-chloro-3-(trimethylsilyl)propyl] sulfide, selenide and selenium dichloride, respectively. The reaction with TeCl₄ affords only diallyl tellurium dichloride. The structures of the compounds were confirmed by ¹H, ¹³C, ⁷⁷Se and ¹²⁵Te NMR techniques.     

Transition states in the reaction of radical addition to the vinyl double bond

The transition states for the addition of^.CH₃, CH₃O^.,^.CCl₃,^.CF₃, and HOO^. radicals to the C and C atoms of ethylene, propylene, styrerie, acrylonitrile, methyl acrylate, vinyl acetate, and vinyl- and vinylidene chlorides were calculated using the MNDO method. A satisfactory correlation between the heats of reaction and activation energies was found. The calculated coefficients of proportionality, 0.4–0.5, are twice as high as those in the Polyani—Semenov equation. The calculated heat of reaction of radical addition was shown to be as «strong» an index of reactivity as the calculated activation barrier.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 680–684, April, 1993.     

Access to the nicotine system by application of a guanidine-catalyzed asymmetric Michael addition of diphenyliminoacetate with 3-pyridyl vinyl ketone

A guanidine-based chiral organocatalyst was successfully applied to the Michael addition of diphenyliminoacetate to pyridyl vinyl ketone as a key reaction for the construction of the nicotine system.     

Highly efficient heterogeneous procedure for the conjugate addition of amines to electron deficient alkenes

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. K₂CO₃ supported on different carriers have been synthesized for the conjugate addition of amines and alkenes. After optimizing the reaction conditions, K₂CO₃/MgO was chosen as the most efficient catalyst for the reactions. The results showed that the catalyst was very efficient for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes. Operational simplicity, without need of any solvent, low cost of the catalyst used, high yields, reusability, excellent chemoselectivity, and applicability to large-scale reactions are the key features of this methodology. Supported by the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science and Technology of China (Grant No. 2006BAE03B06), Shanghai Leading Academic Discipline Project (Grant No. B409), and Shanghai International Cooperation of Science and Technology Project (Grant No. 06SR07101)     

Highly efficient bifunctional organocatalysts for the asymmetric Michael addition of ketones to nitroolefins

A type of secondary-secondary-tertiary triamine bifunctional organocatalysts have been properly designed and synthesized. In our study, the designed catalyst (S)-N-(pyrrolidin-2-ylmethyl)pyridin-2-amine 5 has been shown to be highly efficient to promote the asymmetric Michael addition of ketones to nitroolefins at room temperature, which afforded the corresponding adducts in excellent diastereoselectivities (up to 99:1 dr) and enantioselectivities (up to >99% ee).     

An efficient catalytic asymmetric addition of trimethylsilyl cyanide to aldehydes at room temperature

The BINOL-salen compound (S)-5c in combination with Ti(OⁱPr)₄ is found to catalyze the addition of TMSCN to aldehydes to form chiral cyanohydrins with very good enantioselectivity (75-85% ee). The reactions are carried out in one-pot at room temperature without the need to isolate the chiral Lewis acid catalyst.