Thia-Michael Addition in Diverse Organic Synthesis

Thia-Michael addition reactions are significant for organic syntheses of important class of compounds to form C-S bond and its derivatives. It shows the prominent feature in medicinal field and material science. This review is focused on various methods towards thia-Michael adducts using Michael addition of sulfur containing electron rich species (Michael donor) on electron poor olefins (Michael acceptor). The C-S bond is ideal of making bioactive molecules generalized for the synthesis of various drug molecules and applied in field as insect sprays and polymer substances which are common for daily life. Due to the importance of C-S bond in recent years, novel methods for C-S bond formation were developed, which are more convenient with environment

Synthesis of a Library of 1,5,2-Dithiazepine 1,1-Dioxides. Part 2: Routes to Bicyclic Sultams

The synthesis of a library of bicyclic sultams incorporating the 1,5,2-dithiazepine 1,1-dioxide moiety is reported. Following scaffold synthesis via a one-pot sulfonylation/intramolecular thia-Michael protocol, several additional cyclization strategies have been realized enabling access to new bicyclic sultams

(Z)-Oxopropene-1,3-diyl, a linker for the conjugation of the thiol group of cysteine with amino-derivatized drugs

We have developed a conjugation reaction based on the thia-Michael addition to activated triple bonds, which can be an alternative to maleimides, the most commonly used reagents to link thiol groups (of Cys) to drugs and labels. An amino group is converted into its propynamide and, in aqueous media at 37 °C and pH 7.4, Cys derivatives are added. The oxopropene-1,3-diyl linker is formed with excellent Z selectivity without secondary reactions. No exchange with other thiols is observed

Fe(OTf)2-catalyzed thia-Michael addition reaction : a green synthetic approach to β-thioethers

A convenient Fe(OTf)2‐catalyzed Michael addition reaction of thiols to α,β‐unsaturated carbonyl compounds was developed. The use of a simple procedure (EtOH, room temperature, air atmosphere) allowed to set up effective green catalytic conditions for the C‐S bond formation. The scope of the reaction was demonstrated using various substituted thiols and original Michael acceptors. The corresponding β‐thioethers were obtained in good to excellent yields (up to 99%). Also, the derivatization into the one‐pot thia‐Michael addition/oxidation reaction of 3‐(3‐(phenylthio)butanoyl)oxazolidin‐2‐one using H2O2 has proven to be efficient

Vinyl sulfonyl chemistry-driven unidirectional transport of a macrocycle through a [2]rotaxane

This work has been financially supported by FEDER(EDRF)/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades (P18-FR-2877), grant PID2020-112906GA-I00 funded by MCIN/AIE (/10.13039/501100011033) and Ministerio de Economia y Competitividad (MINECO, Spain) (CTQ2014-55474-C2-2-R and CTQ2017-86125P, co-financed by FEDER funds). Funding for open access APCs provided by Universidad de Granada through a Paid by Read & Publish agreement with RSC.By applying a combination of the coupling-and-decoupling (CAD) chemistry of the vinyl sulfonate group with the click thia-Michael addition to the vinyl sulfone group (MAVS) we performed the irreversible unidirectional transportation of the ring through the linear component in a [2]rotaxane by a chemically and pH-driven flashing energy ratchet mechanism. The design is based on a monostoppered thread precursor bearing a sulfonate stopper, a vinyl sulfone group on the unstoppered end and a dibenzylammonium unit as recognition site for the dibenzo-24-crown-8 macrocycle. First, the ring enters from the vinyl sulfone side and the rotaxane is capped through a thia-Michael addition reaction. Then, the cleavage of the sulfonate group of the opposite stopper using MgBr2 as chemical stimulus and subsequent addition of base (Et3N) promoted the controlled and directional release of the macrocycle into the bulk under mild conditions. The efficiency of the system allowed the in situ operation as demonstrated by NMR and HRMS techniques.FEDER(EDRF)/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades - MCIN/AIE P18-FR-2877Ministerio de Economia y Competitividad (MINECO, Spain) (FEDER funds) CTQ2014-55474-C2-2-R; CTQ2017-86125PUniversidad de GranadaRSCMCIN/AIE PID2020-112906GA-I0

Thia-Michael reaction under heterogeneous catalysis

Thia-Michael reactions between aliphatic and aromatic thiols and various Michael acceptors were performed under environmentally-friendly solvent-free conditions using Amberlyst® A21 as a recyclable heterogeneous catalyst to efficiently obtain the corresponding adducts in high yields. Ethyl acrylate was the main acceptor used, although others such as acrylamide, linear, and cyclic enones were also utilized successfully. Bifunctional Michael donor, 3-mercaptopropanoic acid, positively furnished the product, albeit in a lower yield and after leaving the reaction to take place for a longer time. The catalyst was easy and safe to handle and successfully recycled for five consecutive cycles.peer-reviewe

Olefin cross-metathesis as a valuable tool for the preparation of renewable polyesters and polyamides from unsaturated fatty acid esters and carbamates

Olefin cross-metathesis of unsaturated fatty acid methyl ester (FAME) derived benzyl carbamates with methyl acrylate is described. The obtained by-product{,} an [small alpha]{,}[small beta]-unsaturated ester{,} was further modified via thia-Michael addition reactions in order to synthesize branched AA-type or AB-type monomers for the preparation of polyesters{,} which are tuneable by oxidation. Cross-metathesis of fatty acid derived carbamates was used as a novel approach to prepare linear AB-type monomers{,} which can be used for the preparation of renewable polyamides PA11{,} PA12 and PA15. The necessary fatty acid carbamates were prepared by applying a catalytic Lossen rearrangement procedure. The presented synthesis strategy has potential for the bio-sourced preparation of monomers for the production of polyamides. All prepared polymers were fully characterized by NMR{,} SEC{,} and DSC analyses. Additionally{,} the Young{\u27}s modulus of the prepared long-chain polyamide PA15 was determined

Olefin cross-metathesis as a valuable tool for the preparation of renewable polyesters and polyamides from unsaturated fatty acid esters and carbamates

Olefin cross-metathesis of unsaturated fatty acid methyl ester (FAME) derived benzyl carbamates with methyl acrylate is described. The obtained by-product{,} an [small alpha]{,}[small beta]-unsaturated ester{,} was further modified via thia-Michael addition reactions in order to synthesize branched AA-type or AB-type monomers for the preparation of polyesters{,} which are tuneable by oxidation. Cross-metathesis of fatty acid derived carbamates was used as a novel approach to prepare linear AB-type monomers{,} which can be used for the preparation of renewable polyamides PA11{,} PA12 and PA15. The necessary fatty acid carbamates were prepared by applying a catalytic Lossen rearrangement procedure. The presented synthesis strategy has potential for the bio-sourced preparation of monomers for the production of polyamides. All prepared polymers were fully characterized by NMR{,} SEC{,} and DSC analyses. Additionally{,} the Young{\u27}s modulus of the prepared long-chain polyamide PA15 was determined

Synthesis and applications of new polymer bound catalysts

This dissertation discusses three new types of polymer bound catalysts and their applications. The first type is a polymer bound cation that is an effective spectator ion for nitrate. The nitrate ion is then free to act as a catalyst in aza and thia-Michael reactions and Strecker reactions. The second catalyst was previously reported. However, its structure was incorrectly assigned. The correctly revised structure of the polymer bound azidoproazaphosphatrane shows impressive catalytic activity in the oxa-Michael reaction. The third catalyst is a polymer bound free proazaphosphatrane. It is shown to be catalytically active in the trimerization of an isocyanate to an isocyanurate and in the synthesis of a diaryl ether. Finally, two interesting reactions are reported where proazaphosphatranes are shown to increase the reactivity of silicon compounds. The first is the production of cyanohydrins and protected cyanohydrins where and activated trimethylsilylcyanide adds to aldehydes and ketones. The second is reduction of aldehdyes and ketones with the use of poly(methylhydrosiloxane)