Cyclic Dithioacetals Research Articles

New Heterocyclic Organosulfur Compounds Derived from Dithioacetals

AbstractThe dithioacetalization of lactaldehyde derivatives with ethane-1,2-, propane-1,3-, butane-1,4-, and pentane-1,5-dithiols in the presence of 4 mol% of scandium triflate has been described. A series of cyclic dithioacetals were obtained with yields ranging from quantitative to 37%. The dithioacetalization of lactaldehyde derivatives with butane-1,4-dithiol and pentane-1,5-dithiol groups are accompanied by the formation of 14- and 16-membered macrocyclic sulfur structures with yields of 3% and 18%, respectively. In the case of a cyclic dithioacetal derivative with three methylene groups, a diastereoisomeric pair of enantiomers was obtained, the structure of which was confirmed by single-crystal X-ray diffraction analysis. Dithioacetals are useful building blocks in the synthesis of complex chemical structures. Macrocyclic compounds can be used to complex metal ions.

Synthesis of 1,1,4,4-tetra-aryl-1,3-butadienes possessing sulfur substituents at 2,3-positions via dithiol intermediates and their characteristic electrochromic behaviors

Abstract Synthesis and reactions of 2,3-dimercapto-1,1,4,4-tetra-aryl-1,3-butadienes as versatile intermediates for sulfur-containing 1,1,4,4-tetra-aryl-1,3-butadiene derivatives are described. The dithiols were prepared from cyclic polysulfides and their structures were characterized by single-crystal X-ray diffraction analyses. Both cyclic dithioacetals and acyclic S,S′-dimethyl derivatives were prepared by facile reactions of the corresponding dithiols. The acyclic sulfur-substituted dienes exhibited electrochromic behavior in which the solution turned from colorless to dark purple under an external electric field above a potential of 0.3 V vs Fc/Fc+.

Base Dependent Rearrangement of Dithiane and Dithiolane under Visible-light Photoredox catalysis.

The rearrangement of dithiolanes and dithianes to access disulfide-linked-dithioesters under visible-light photoredox catalysis via controlled C-S bond cleavage has been disclosed. Unlike, the usual deprotection of dithioacetals to corresponding aldehydes under the oxidative conditions, we observed unique regioselective oxidative reactivity of five and six membered cyclic dithioacetals to form disulfide-linked-dithioesters by exchanging DMAP and imidazole bases. The generality of the protocol has been demonstrated by exploring a wide range of substrates. As an application, in situ generated thiyl radical has been trapped with disulfides to prepare hetero-disulfides of potential utility. The protocol proved to be practical on gram scale quantity and relied on clean energy source for the transformation. Based on the series of control experiments, cyclic voltammetry and Stern-Volmer studies the plausible mechanism has been proposed.

Synthesis of quinozilinium fluoroborate salts from harmine

Molecules possessing harmine moiety are reported to exhibit marked fungicidal and bactericidal activities. In this study, various quinozilinium tetrafluoroborate salts were synthesized using acylic and cyclic oxoketene dithioacetals followed by cycloaromatization from Harmine. All of these synthesized compounds were characterized by 1H NMR, 13C NMR, Mass and CHN analysis. This methodology would find wide usage in the preparation of indolo quinozilinium -based library of small molecules useful for medicinal chemistry and in drug discovery.

Chemoselective Thioacetalisation of Aldehydes Catalysed by a MCM-41-Supported Mercapto Ruthenium Complex

A variety of aromatic and aliphatic aldehydes can be easily converted into the corresponding cyclic and acyclic dithioacetals in the presence of MCM-41-supported mercapto ruthenium complex (MCM-41-SH-RuCl3) in acetonitrile. This supported ruthenium complex can be recovered by simple filtration and reused several times without noticeable loss of activity.

Highly Selective Aluminum-Catalyzed Oxidation of Cyclic Dithioacetals

Following their previous work, the authors apply an aluminum(salalen) complex to the oxidation of cyclic dithioacetals and high levels of diastereo-and enantioselectivity are achieved. Overoxidation has hindered the development of asymmetric oxidation of dithioacetals, but here, the oxidation is completely controlled to give either monoxides or dioxides depending on the equivalents of hydrogen peroxide.

Catalytic Asymmetric Oxidation of Cyclic Dithioacetals: Highly Diastereo- and Enantioselective Synthesis of the S-Oxides by a Chiral Aluminum(salalen) Complex

Aluminum(salalen) complex 1 [salalen = half-reduced salen, salen = N,N'-ethylenebis(salicylideneiminato)] was found to be a highly efficient catalyst for asymmetric oxidation of cyclic dithioacetals in the presence of 30% hydrogen peroxide as an oxidant. In the reaction of a series of 2-substituted 1,3-dithianes bearing alkyl, alkenyl, alkynyl, and aryl groups as the substituent, the trans-monoxides were obtained in high yields with 19:1 → >20:1 dr (diastereomeric ratio) and 98-99% ee (enamtiomeric excess). The reaction of nonsubstituted 1,3-dithiane also proceeded in a highly enantioselective manner to give the monoxide with a small formation of the trans-1,3-dioxide, an overoxidation product. Five-membered 1,3-dithiolanes and seven-membered 1,3-dithiepanes also underwent oxidation to give monoxides with high diastereo- and enantioselectivity. It was found that the equilibrium between the two chairlike conformers of dithianes has relevance to the observed diastereoselectivity in the first oxidation process, and the dioxide formation in the oxidation of 1,3-dithiane and its stereochemistry also can be explained by the conformational equilibrium of the product monoxide.

ChemInform Abstract: Sulfonated Charcoal, a Mild and Efficient Reagent for the Preparation of Cyclic Acetals, Dithioacetals, and Benzodioxepins.

ChemInform Abstract: Sulfonated Charcoal, a Mild and Efficient Reagent for the Preparation of Cyclic Acetals, Dithioacetals, and Benzodioxepins.

Lanthanum(III) nitrate hexahydrate catalyzed chemoselective thioacetalization of aldehydes†

A wide variety of cyclic and acyclic dithioacetals have been prepared chemoselectively from their corresponding aldehydes with 1,3-dithiol and ethanethiol using catalytic amounts of lanthanum(III) nitrate hexahydrate as a catalyst at room temperature. †IICT Communication # 061103.

Facile Synthesis of Substituted Dihydro‐1,4‐dithiins and ‐1,4‐dithiepins from α‐Oxo Ketene Cyclic Dithioacetals.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Facile synthesis of substituted dihydro-1,4-dithiins and -1,4-dithiepins from α-oxo ketene cyclic dithioacetals

A novel and facile synthesis of substituted 2,3-dihydro-1,4-dithiins and 6,7-dihydro-5 H-1,4-dithiepins based on the reactions of α-bromo/hydroxy ketones with α-oxo ketene cyclic dithioacetals has been developed. A general mechanism for the reactions is proposed.

A Simple and Practical Synthetic Protocol for Thioacetalization of Carbonyl Compounds.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Selective Thioacetalization of Aldehydes Catalyzed by Aqueous Zinc Tetrafluoroborate.

A wide range of cyclic dithioacetals are prepared from the corresponding aldehydes in the presence of aqueous solution of zinc tetrafluoroborate.

Scandium Chloride-Catalyzed Chemoselective Thioacetalization of Aldehydes

A wide variety of acyclic and cyclic dithioacetals can be prepared chemoselectively from the corresponding aldehydes by employing a catalytic amount of scandium chloride in acetonitrile at room temperature.

Selective Thioacetalization of Aldehydes Catalyzed by Aqueous Zinc Tetrafluoroborate

A wide range of cyclic dithioacetals are prepared from the corresponding aldehydes in the presence of aqueous solution of zinc tetrafluoroborate.

Nickel(II) Chloride as an Efficient and Useful Catalyst for Chemoselective Thioacetalization of Aldehydes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Iododecarboxylation of α‐Carboxylate, α‐Cinnamoyl Ketene Cyclic Dithioacetals.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Syntheses and Characterization of Tributyltin(IV) Carboxylates Containing α‐Oxoketene Cyclic Dithioacetals

Five aquatributyltin‐2‐(dialkylthio)methylene‐3‐oxo‐5‐aryl‐4‐pentenoates (3) were synthesized and characterized by IR spectra, 1H NMR spectra, 13C NMR spectra and elemental analyses. The IR spectra of (3) show strong O—H stretching modes in the region of 3384–3455 cm‐1. In the 1H NMR spectra of (3), signals due to the protons of an α‐oxoketene dithioacetal segment shift upfield compared to those of free acids (2). This is indicative of the formation of the tin ester complexes. The structure of 4‐O2N‐C6H4CH=CHCOC(C3H4S2)CO2Sn(C4H9)3·(H2O) (3d) was determined by X‐ray diffraction and showed two molecules in an asymmetric unit cell. The tin(IV) is coordinated with three carbon atoms, an oxygen of carboxylate and an oxygen of water and forms a five‐coordinate, distorted trigonal bipyramidal configuration. There is no intermolecular O—Sn coordination in (3d), but a molecule of water acts as one of the five ligands and coordinates directly to the tin atom. The tin‒oxygen (water) bond distance in (3d) is discussed in relation to that in other aquatin(IV) complexes.

Nickel(II) chloride as an efficient and useful catalyst for chemoselective thioacetalization of aldehydes

A wide variety of acyclic and cyclic dithioacetals can be prepared chemoselectively from the corresponding aldehydes by employing a catalytic amount of nickel(II) chloride in dry CH 2Cl 2–MeOH (5:1) at room temperature in good yields. Some of the major advantages of this procedure are high chemoselectivity, ease of operation, high yields and also compatibility with other protecting groups.

ChemInform Abstract: Highly Enantioselective Oxidation of Cyclic Dithioacetals by Using a Ti(Salen) and Urea×Hydrogen Peroxide System.

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