Allylic Sulfones Research Articles

Regio- and Enantioselective Synthesis of Chiral Allylic Sulfones

Regio- and Enantioselective Synthesis of Chiral Allylic Sulfones

Palladium-Catalyzed Regio- and Enantioselective Hydrosulfonylation of 1,3-Dienes with Sulfinic Acids: Scope, Mechanism, and Origin of Selectivity.

Chiral sulfones are important structural motifs in organic synthesis because of their widespread use in pharmaceutical chemistry. In particular, chiral allylic sulfones have drawn particular interest because of their synthetic utility. However, enantioselective synthesis of 1,3-disubstituted unsymmetrical chiral allylic sulfones remains a challenge. In this article, we report a protocol for (R)-DTBM-Segphos/Pd-catalyzed regio- and enantioselective hydrosulfonylation of 1,3-dienes with sulfinic acids, which provides atom- and step-economical access to 1,3-disubstituted chiral allylic sulfones. The reaction occurs under mild conditions and has a broad substrate scope. Combined experimental and computational studies suggest that the reaction is initiated by a ligand-to-ligand hydrogen transfer followed by a C-S bond reductive elimination via a six-membered transition state. Steric repulsion between the olefinic C-H of the substrate and the tert-butyl group of (R)-DTBM-Segphos was found to be a key factor in the enantiocontrol.

Tungsten-Catalyzed Allylic Substitution with a Heteroatom Nucleophile: Reaction Development and Synthetic Applications.

A tungsten-catalyzed allylic allylation of sodium sulfinate as the heteroatom nucleophile was developed. The reaction utilizes inexpensive and readily available (CH3CN)3W(CO)3 as a precatalyst and proceeds at 60 °C temperature in the presence of 2,2'-bipyridine and its derivatives as ligand. The synthetic utility of allylic sulfones as electrophile was further demonstrated through Suzuki-Miyaura cross-coupling as showcased by the formal synthesis of (±)-hinokiresinol.

Preparation, characterization of feather protein-g-poly(sodium allyl sulfonate) and its application as a low-temperature adhesive to cotton and viscose fibers for warp sizing

Fulfilling high-valued utilization of feather wastes will favor overcoming environmental issues and promoting the poultry farmers’ income. This study developed a new bio-based protein sizing agent [feather protein-g-poly(sodium allyl sulfonate) (FP-g-PSAS)] with high adhesion capacity to viscose and cotton fibers at low temperature, through graft copolymerization of feather protein with SAS monomer by building an ammonium persulfate (APS)/SH groups (on the protein chains) redox system. Fourier transform infrared (FTIR) spectroscopy and energy dispersive x-ray spectrometer (EDS) demonstrated the successful preparation of FP-g-PSAS samples. The samples were also characterized by scanning electron microscopy (SEM), thermogravimetric (TG) and x-ray diffraction (XRD). Viscosity, water-solubility, light transmittance and adhesion of the samples were investigated. The FP-g-PSAS exhibited high water-solubility and light transmittance. Compared with feather protein, an increased viscosity and an improved adhesion to both fibers for FP-g-PSAS samples were exhibited at 60 °C. With the rises in grafting ratios, viscosity and adhesion strengths to both fibers gradually increased. The FP-g-PSAS samples had the similar adhesion strengths in comparison with the modified starches investigated in our previous works. These results indicated that FP-g-PSAS showed the potential in the application of viscose and cotton warp sizing at a low temperature of 60 °C.

Total Syntheses of C60- and C100-Dolichols.

C60- and C100-dolichols were synthesized. A Z-selective Wittig reaction was achieved with high selectivity in a microflow system to realize the scalable supply of the Z-isoprene unit. An isoprene chain was efficiently elongated by an SN2-type coupling between allyl sulfone and allyl chloride using t-BuOK. These key reactions enabled the efficient syntheses of dolichols. This study will pave the way for the functional studies of dolichols.

One-pot two-step reaction of selenosulfonate with isocyanides and allyl alcohol under aqueous conditions: Atom-economic synthesis of selenocarbamates and allyl sulfones

In many reactions involving selenosulfonate or thiosulfonate, the sulfone group often leaves in form of benzenesulfinic acid or sodium benzenesulfinate. A one-pot two-step reaction of selenosulfonate with isocyanides and allyl alcohol under aqueous conditions to afford selenocarbamates and allyl sulfone compounds is reported. The sulfinic acid as the first-step side product is converted to the allyl sulfone compound by water promoted reaction with allyl alcohol. Water acts as both an oxygen source of selenocarbamates and as a promoter to drive the second step reaction. The reactions have the advantages of mild conditions, green, environment-friendly, and high atomic economy.

Reciprocal-Activation Strategy for Allylic Sulfination with Unactivated Allylic Alcohols.

A reciprocal-activation strategy for allylic sulfination with unactivated allylic alcohols was developed. In this reaction, the hydrogen bond interaction between allylic alcohols and sulfinic acids allowed for reciprocal activation, which enabled a dehydrative cross-coupling process to occur under mild reaction conditions. This reaction worked in an environmentally friendly manner, yielding water as the only byproduct. A variety of allylic sulfones could be obtained in good to excellent yields with wide functional group tolerance. In gram scale reactions, allylic sulfones could be conveniently isolated in high yield by filtration.

Effect of comonomer on the Cu-BDC/Poly(NMA-coSAS) foams templating from CO2-in-water emulsion: Adsorptive and bacteriostatic applications

Herein, Cu-BDC/poly(N-methylol acrylamide-co-sodium allyl sulfonate) [Cu-BDC/P(NMA-co-SAS)] macroporous foam was synthesized templating from CO2-in-water (C/W) high internal phase emulsions (HIPEs), and using Cu-BDC as Pickering emulsifier. The features of the macroporous monolith, such as structure and void diameter, can be adjusted by changing the emulsion composition. The resultant macroporous foams have a low bulk density (0.317 g cm−3), high porosity (79.60 %), suitable pore volume (3.956 cm3 g-1), and pore size ranging from 5.46 μm to 36.47 μm. The maximum swelling degree of 20.7 g/g for the composite foam was obtained when a high MBAM dosage of 12.5 wt% was used. Moreover, adsorption behavior and antibacterial property of the composite foam with 5.0 wt% Cu-BDC were investigated. The results proved that the obtained foam could behave as a potential multi-functional antibacterial material.

Visible-Light-Mediated Manganese-Catalyzed Allylation Reactions of Unactivated Alkyl Iodides.

Herein, we report a protocol for visible-light-mediated allylation reactions between unactivated alkyl iodides and allyl sulfones under mild conditions with catalysis by inexpensive and readily available Mn2(CO)10. This protocol is compatible with a wide array of sensitive functional groups and has a broad substrate scope with regard to both alkyl iodides and allyl sulfones.

Allyl 4-Chlorophenyl Sulfone as a Versatile 1,1-Synthon for Sequential α-Alkylation/Cobalt-Catalyzed Allylic Substitution

Despite their unique potential as rare 1,1-dipole synthons, allyl sulfones are rarely used in target-oriented syntheses, likely due to the lack of a general catalytic method for their branch-selective allylic substitution. Herein, we identified allyl 4-chlorophenyl sulfone as a versatile linchpin for both base-mediated α-derivatization and subsequent cobalt-catalyzed allylic substitution. The sequential transformations allow for highly regioselective access to branched allylic substitution products with a variety of aliphatic side chains. The photoredox-enabled­ ­cobalt catalysis is indispensable for achieving high yields and regioselectivity­ for the desulfonylative substitution in contrast to traditional metal-catalyzed protocols, which lead to inferior outcomes in the corresponding transformations.

When Light Meets Nitrogen-Centered Radicals: From Reagents to Catalysts.

Nitrogen-centered radicals (NCRs) are a versatile class of highly reactive species that have a longer history than the classical carbon-based radicals in synthetic chemistry. Depending on the N-hybridization and substitution patterns, NCRs can serve as electrophiles or nucleophiles to undergo various radical transformations. Despite their power, progress in nitrogen-radical chemistry is still slow compared with the popularity of carbon radicals, and their considerable synthetic potential has been largely underexplored, which is, as concluded by Zard, mainly hampered by "a dearth of convenient access to these species and a lack of awareness pertaining to their reactivity".Over the past decade, visible-light photoredox catalysis has been established as a powerful toolbox that synthetic chemists can use to generate a diverse range of radical intermediates from native organic functional groups via a single electron transfer process or energy transfer under mild reaction conditions. This catalytic strategy typically obviates the need for external stoichiometric activation reagents or toxic initiators and often enables traditionally inaccessible ionic chemical reactions. On the basis of our long-standing interest in nitrogen chemistry and catalysis, we have emphasized the use of visible-light photoredox catalysis as a tactic to discover and develop novel methods for generating NCRs in a controlled fashion and synthetic applications. In this Account, we describe our recent advances in the development of visible-light-driven photoredox-catalyzed generation of NCRs and their synthetic applications.Inspired by the natural biological proton-coupled electron transfer (PCET) process, we first developed a strategy of visible-light-driven photoredox-catalyzed oxidative deprotonation electron transfer to activate the N-H bonds of hydrazones, benzamides, and sulfonamides to give the corresponding NCRs under mild reaction conditions. With these reactive species, we then achieved a range of 5-exo and 6-endo radical cyclizations as well as cascade reactions in a highly regioselective manner, providing access to a variety of potentially useful nitrogen heterocycles. To further expand the repertoire of possible reactions of NCRs, we also revealed that iminyl radicals, derived from O-acyl cycloalkanone oxime esters, can undergo facile ring-opening C-C bond cleavage to give cyanoalkyl radicals. These newly formed radical species can further undergo a variety of C-C bond-forming reactions to allow the synthesis of diverse distally functionalized alkyl nitriles. Stimulated by these studies, we further developed a wide variety of visible-light-driven copper-catalyzed radical cross-coupling reactions of cyanoalkyl radicals. Because of their inherent highly reactive and transient properties, the strategy of heteroatom-centered radical catalysis is still largely underexplored in organic synthesis. Building on our understanding of the fundamental chemistry of NCRs, we also developed for the first time the concept of NCR covalent catalysis, which involves the use of in situ-photogenerated NCRs to activate allyl sulfones, vinylcyclopropanes, and N-tosyl vinylaziridines. This catalytic strategy has thus enabled efficient difunctionalization of various alkenes and late-stage modification of complex biologically active molecules.In this Account, we describe a panoramic picture of our recent contributions since 2014 to the development and application of the visible-light-driven photoredox systems in the field of NCR chemistry. These studies provide not only efficient methods for the synthesis of functionally rich molecules but also some insight into the exploration of new reactivity or reaction modes of NCRs.

Preparation of poly (styrene‐co‐allyl sulfonic acid) as a novel catalyst for the alcoholysis of dioscin

This work describes the preparation of a novel solid acid, poly (styrene‐co‐allyl sulfonic acid) (St‐SAA), and its activity test for extracting diosgenin from Dioscorea Zingiberensis C.H. Wright (DZW). The solid acid was synthesized by the radical polymerization of styrene and sodium allyl sulfonate in water/ethanol solution, followed by the acidification. The prepared solid acid was characterized by infrared spectrum (FTIR), thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), element analysis, and scanning electron microscope. The solid acid catalyst was used to extract diosgenin from DZW. It was found that the alcoholysis activity of the solid acid was higher than the hydrolysis activity of sulfuric acid with the same mass under the same conditions. Besides, the solid acid can be separated from the reaction mixture for the recycling extraction of diosgenin, and the solid acid has no loss of mass and no decrease of alcoholysis activity after repeated cycles.

Silver-Catalyzed Decarboxylative Allylation of Difluoroarylacetic Acids with Allyl Sulfones in Water.

A practical silver-catalyzed decarboxylative allylation of α,α-difluoroarylacetic acids with allyl sulfones is described, which provides a variety of β,β-difluorinated alkenes in good yields. Notably, the reaction proceeds smoothly in water with good functional group tolerance. The practicality and synthetic value of this process was demonstrated by scaled-up experiment and elaboration of the products via reduction or Heck reaction. Primary mechanism investigations suggest that a radical process might be involved.

Palladium nanoparticles as efficient catalyst for C-S bond formation reactions.

The development of green, economical and sustainable chemical processes is one of the primary challenges in organic synthesis. Herein, we report an efficient and heterogeneous palladium-catalyzed sulfonylation of vinyl cyclic carbonates with sodium sulfinates via decarboxylative cross-coupling. Both aliphatic and aromatic sulfinate salts react with various vinyl cyclic carbonates to deliver the desired allylic sulfones featuring tri- and even tetrasubstituted olefin scaffolds in high yields with excellent selectivity. The process needs only 2 mol% of Pd2(dba)3 and the in situ formed palladium nano-particles are found to be the active catalyst.

Regio- and Enantioselective Synthesis of Chiral Allylic Sulfones

Key words allylic sulfones - enantioselectivity - homogeneous catalysis - palladium catalysis - regioselectivity

Regio‐ and Enantioselective Synthesis of Sulfone‐Bearing Quaternary Carbon Stereocenters by Pd‐Catalyzed Allylic Substitution

AbstractChiral sulfones are of great importance in medicinal chemistry and chemical synthesis. Efficient methods for preparing enantiomerically enriched sulfone‐containing molecules can therefore be of significant value; such methods, however, are uncommon. Herein, we report the first general palladium‐catalyzed sulfonylation of vinyl cyclic carbonates with sodium sulfinates. A series of enantiomerically enriched tertiary allylic sulfones were synthesized in good yields with excellent enantiomeric ratios. Both aliphatic‐ and aryl‐substituted vinyl cyclic carbonates are suitable reactants with excellent results. This reaction features broad substrates scope, readily available starting materials, excellent regio‐ and enantioselectivity, and synthesis of sulfone‐bearing quaternary carbon stereocenters. Through the sulfonylation of geranyl derived cyclic carbonate 1 h, we achieve the formal total synthesis of (+)‐agelasidine A.

Regio- and Enantioselective Synthesis of Sulfone-Bearing Quaternary Carbon Stereocenters by Pd-Catalyzed Allylic Substitution.

Chiral sulfones are of great importance in medicinal chemistry and chemical synthesis. Efficient methods for preparing enantiomerically enriched sulfone-containing molecules can therefore be of significant value; such methods, however, are uncommon. Herein, we report the first general palladium-catalyzed sulfonylation of vinyl cyclic carbonates with sodium sulfinates. A series of enantiomerically enriched tertiary allylic sulfones were synthesized in good yields with excellent enantiomeric ratios. Both aliphatic- and aryl-substituted vinyl cyclic carbonates are suitable reactants with excellent results. This reaction features broad substrates scope, readily available starting materials, excellent regio- and enantioselectivity, and synthesis of sulfone-bearing quaternary carbon stereocenters. Through the sulfonylation of geranyl derived cyclic carbonate 1 h, we achieve the formal total synthesis of (+)-agelasidine A.

Regio‐ and Enantioselective Preparation of Chiral Allylic Sulfones Featuring Elusive Quaternary Stereocenters

AbstractWe describe here the first general asymmetric synthesis of sterically encumbered α,α‐disubstituted allylic sulfones via Pd‐catalyzed allylic substitution. The design and application of a new and highly efficient phosphoramidite ligand (L10) proved to be crucial, and a wide variety of challenging allylic sulfones featuring quaternary stereocenters could be obtained in good yields and with good to excellent levels of regio‐ and enantioselectivities under attractive process conditions. The developed methodology employs easily accessible chemical feedstock including racemic allylic precursors and sodium sulfinates. The utility of the method is further demonstrated by the synthesis of the sesquiterpene (−)‐Agelasidine A.

Regio- and Enantioselective Preparation of Chiral Allylic Sulfones Featuring Elusive Quaternary Stereocenters.

We describe here the first general asymmetric synthesis of sterically encumbered α,α-disubstituted allylic sulfones via Pd-catalyzed allylic substitution. The design and application of a new and highly efficient phosphoramidite ligand (L10) proved to be crucial, and a wide variety of challenging allylic sulfones featuring quaternary stereocenters could be obtained in good yields and with good to excellent levels of regio- and enantioselectivities under attractive process conditions. The developed methodology employs easily accessible chemical feedstock including racemic allylic precursors and sodium sulfinates. The utility of the method is further demonstrated by the synthesis of the sesquiterpene (-)-Agelasidine A.

Direct Synthesis of Substituted (Z)‐Allylic Sulfones by Palladium‐Catalyzed Sulfonylation of Vinylethylene Carbonates with Sodium Sulfinates

AbstractA palladium‐catalyzed highly stereoselective sulfonylation of vinylethylene carbonates for the precise synthesis of structurally diverse (Z)‐allylic sulfones was achieved with excellent regioselectivity and stereoselectivity (Z/E ratio, up to 99 : 1). This protocol used inexpensive sodium sulfinates as sulfonyl sources to construct valuable (Z)‐allylic sulfones in good to excellent yields. The controlling experiment suggested that the hydroxyl proton came from the α‐hydrogen of sulfone group through 1, 5‐H shift.