Metal complex-catalyzed synthesis of dihydrothiapyrans from dialkyl sulfoxides and 1,3-dienes

A preparative method has been developed for the synthesis of dihydrothiapyrans from dialkyl sulfoxides and 1,3-dienes, catalyzed by palladium and nickel complexes. The scope of this reaction has been assessed, and a mechanism proposed, using 1,3-dienes and sulfoxides of varying structure.Institute of Chemistry, Bashkir Science Center, Ural Branch, Russian Academy of Sciences, 450054 Ufa. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 160–166, January, 1992.     

Reaction of thioketones with propiolic acids

The reaction of adamantane-2-thione with propiolic acid afforded a novel type of cycloadduct, spiro[adamantane-2,2'-6'H-[1,3]-oxathiin]-6'-one (3a), in quantitative yield. The reaction of thiobenzophenone with propiolic acid gave 2,2-diphenyl-6'H-[1,3]-oxathiin]-6'-one and 4-phenyl-3-thia-3,4-dihydronaphthoic acid in 34% and 35% yields, respectively. The reaction might proceed through a concerted process, as confirmed by kinetics. The reaction of adamantane-2-thione with 2-butynoic acid or phenylpropiolic acid gave the corresponding adducts regioselectively. Interestingly, only one isomer was obtained by the reaction of thiofenchone with propiolic acid, suggesting that the reaction proceeded diastereospecifically. Oxidation of adducts by dimethyldioxirane or m-chloroperoxybenzoic acid gave the corresponding sulfoxides and sulfones. The sulfoxides were thermally decomposed to give disulfide or another type of 1,3-oxathiin-6-one.     

1，2－联烯亚砚和1，2－联烯砜的反应

1，2－联烯亚砜和1，2－联烯砜是重要的含硫联烯化合物，综述了1，2－联烯 亚砜和1，2－联烯砜的亲核加成、亲电加成、Diels-Alder反应、1，3－偶极加成 、[2+2]环加成等反应以及在天然产物中的应用。     

Application of a novel 1,3-diol with a benzyl backbone as chiral ligand for asymmetric oxidation of sulfides to sulfoxides

A chiral 1,3-diol with a benzyl backbone has been used for the asymmetric oxidation of sulfides to sulfoxides. Moderate to good yields and enantioselectivity (upto 87% ee) have been observed.     

Synthesis and Addition Reactions of 1,3-Thiazole-5(4H)-thione Oxides

1,3-Thiazole-5(4H)-thione oxides 2 were prepared by oxidation of the corresponding 1,3-thiazole-5(4H)-thiones 1 with m-chloroperbenzoic acid (Table 1). Addition reactions of 2 with organolithium and Grignard reagents yielded 4,5-dihydro-4,4-dimethyl-1,3-thiazol-5-yl methyl sulfoxides of type 4 via thiophilic attack (Table 2). Whereas the reaction with the organolithium compounds proceeded with fair-to-excellent yields, the Grignard reagents reacted only very sluggishly. The sulfoxides 4 could also be prepared via oxidation of 4,5-dihydro-4,4-dimethyl-5-(methylthio)-1,3-thiazoles of type 3 with m-chloroperbenzoic acid, together with the corresponding sulfones 5 (Scheme 1).     

Synthesis of 1,3-Bis[3-X-2-(X-acetoxy)propyl]-6-methyl- 1,2,3,4-tetrahydropyrimidine-2,4-diones

A procedure was developed for synthesizing nitrogen-and-sulfur-containing pyrimidine derivatives by reactions of 1,3-bis(3-chloro-2-hydroxypropyl)-6-methyluracil with 1-butanethiol and chloroacetyl chloride, followed by treatment of the resulting 1,3-bis[3-chloro-2-(chloroacetoxy)propyl]-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione with 1-butanethiol, morpholine, and piperidine. Oxidation of the sulfur-containing products with NaIO₄ gave the corresponding sulfoxides.     

Enzyme‐mediated catalytic asymmetric oxidations

Enantiomerically pure sulfoxides are excellent chiral auxiliares for asymmetric synthesis and in the preparation of several enantiopure biologically active compounds. We have explored biocatalytic approaches based on the use of heme peroxidases and flavin monooxygenases such as chloroperoxidase and cyclohexanone monooxygenase respectively. By using isolated enzymes or whole‐cell biotransformations, we have prepared alkyl aryl sulfoxides, 1,3‐dithioacetal‐1‐oxides, dialkyl sulfoxides, and thiosulfinates in high enantiomeric excess. An active site model of cyclohexanone monooxygenase has been proposed in order to explain and to predict the absolute configuration of the product. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:467–473, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10074     

Wacker-type oxidative functionalization of β-substituted unsaturated sulfoxides

The Wacker-type oxidation is an important procedure catalyzed by palladium complexes. A mild and general method for the preparation of β-substituted-δ-oxosulfoxides from the corresponding β-substituted-γ,δ-unsaturated sulfoxides is described. The products are versatile synthetic intermediates for the preparation of syn- and anti-1,3-diol and 1,3-aminoalcohol derivatives.     

The first example of magnesium carbenoid 1,3-CH insertion reaction: a novel method for synthesis of cyclopropanes from 1-chloroalkyl phenyl sulfoxides in high yields

Treatment of 1-chloroalkyl phenyl sulfoxides having a geminal methyl group or a geminal benzyl group at the 2-position in THF at −78 °C with isopropylmagnesium chloride gave magnesium carbenoids. Carbenoid 1,3-CH insertion reaction of the magnesium carbenoids took place instantaneously to afford cyclopropanes in high to quantitative yields.     

A new approach to the reduction of sulfoxides to sulfides with 1,3-dithiane in the presence of electrophilic bromine as catalyst

A new, mild, and novel method is described for the efficient deoxygenation of sulfoxides to their corresponding sulfides with 1,3-dithiane at room temperature in the presence of catalytic amounts of N-bromosuccinimide (NBS), 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO), or Br(2) as the source of electrophilic bromine.     

A DFT Study of the Structure and Relative Stability of 1,3-Thiasilacycloalkanes and Their S-Functional Derivatives

A series of 1,3-thiasilacycloalkanes and their S-oxides, S,S-dioxides, and sulfonium salts were studied by the DFT (B3LYP/6-31G*) method. In six-membered sulfoxides, the oxygen atom preferentially occupies the axial position, whereas in the corresponding sulfonium salts the S-alkyl group occupies the equatorial position. The calculation results explain the lower hydrolytic stability of the five-membered rings compared to the six-membered analogs and the lower stability of sulfoxides compared to sulfones.     

The preparation of 3,5-disubstituted tetrahydro-4H-1,3,5-oxadiazine-4-thiones,tetrahydro-4H-1,3,5-thiadiazin-4-ones,and tetrahydro-4H-1,3,5-thiadiazine-4-thiones

The reaction of 1,3-disubstituted thioureas with formaldehyde under acidic conditions with removal of water yielded 3,5-disubstituted tetrahydro-4H-1,3,5-oxadiazine-4-thiones. When hydrogen sulfide was bubbled through the reaction mixture, the corresponding tetrahydro-4H-1,3,5-thiadiazine-4-thiones were formed. Similarly, starting from 1,3-disubstituted ureas, a number of tetrahydro-4H-1,3,5-thiadiazine-4-ones were prepared. The latter compounds were also oxidized to the corresponding sulfoxides and sulfones.     

Nucleophilic additions to alkylidene bis(sulfoxides): stereoelectronic effects in vinyl sulfoxides

Conjugate additions of nucleophiles (e.g. enolates, amines and malonate anions) to bis(p-tolylsulfinyl)alkenes, alkylidene-1,3-dithiane-1,3-dioxides and alkylidene-1,3-dithiolane-1,3-dioxides have recently been published. Reasons for different selectivities and reaction rates will be discussed by consideration of steric and electronic effects. The preferred mode of attack can be explained by stereoelectronic effects (hyperconjugation) in the primarily carbanion, which is stabilized by n-->S-O-sigma* interaction with an antiperiplanar S=O group. Calculation of the transition states [BP86/aug-TZVP] for the addition of acetone enolate to the dithiane-derived alkylidene bis(sulfoxide) revealed that 6.6-7.3 kJ mol(-1) more energy is needed for an attack leading to a less-stabilized carbanion. Two axial S=O groups in dithiolane-derived alkylidene bis(sulfoxides) lead to a higher reactivity towards nucleophiles.     

REGIOSELECTIVITY OF METALATION OF 1,3-DITHIOLANES AND 1,3-DITHIOLANE 1-OXIDES

Abstract

Deprotonation of 1,3-dithiolane 1-oxide (3) and trans-2-phenyl-1,3-dithiolane 1-oxide (5) leads to cleavage of the derived anions. Cleavage reactions do not occur with trans-hexahydro-1,3-benzodithiole (7), its 1-oxide, or its 1,1-dioxide all of which can be metalated and alkylated quantitatively at C-2. The preparation and reactions of the sulfoxides derived from 7 are not highly stereoselective.     

Synthesis and Some Reactions of 2‐Acyl‐2‐alkyl‐1,3‐dithiolane 1,1‐Dioxides

The selective formation of optically active 2‐acyl‐2‐alkyl‐1,3‐dithiolane 1,1‐dioxides from the corresponding 2‐acyl‐2‐alkyl‐1,3‐dithiolane 1‐oxides, by reaction with OsO₄ and NMO in acetone, is reported. These compounds underwent stereoselective reactions at the carbonyl group of the acyl group with organometallic reagents. These reactions were completely regioselective, and no attack at either of the S‐atoms was observed, unlike similar reactions with the corresponding sulfoxides. The nature of the metal atom had a direct effect upon the configuration of the product alcohols.     

A novel method for the reduction of sulfoxides with the N,N,N’,N’-tetrabromobenzene-1,3-disulfonamide (TBBDA)/PPh3 system

A new method is described for the reduction of sulfoxides to sulfides using N,N,N’,N’-tetrabromobenzene-1,3-disulfonamide [TBBDA] in combination with triphenylphosphine. Good to excellent yields, short reaction times, high efficiency and facile isolation of the desired products are the advantages of this method.     

Pyrrolo[2,1-b]thiazole derivatives by asymmetric 1,3-dipolar reactions of thiazolium azomethine ylides to activated vinyl sulfoxides

1,3-Dipolar reactions of thiazolium azomethine ylides to enantiopure cyclic and acyclic vinyl sulfoxides provide an efficient access to polyfunctionalized pyrrolo[2,1-b][1,3]thiazoles in a highly regio- and stereoselective manner. Regioselectivity can be inverted by modifying the position of the sulfinyl group at the double bond of the sulfinylfuranones. The sulfoxide is the main controller of the endo selectivity of these processes as well as of the pi-facial selectivity in reactions of (Z)-3-p-tolylsulfinylacrylonitriles. In contrast, the pi-facial selectivity in reactions of 5-alkoxy-3-p-tolylsulfinyl furan-2(5H)-ones is mainly controlled by the configuration at C-5, affording the anti adducts with respect to the alkoxy group as the major or exclusive adducts.     

The mechanism of permanganate oxidation of sulfides and sulfoxides

Coupled-cluster (CCSD) and density functional computations are used to investigate historically competing mechanisms for the permanganate oxidation of sulfides and sulfoxides. The calculations all lead to a mechanism of 1,3-dipolar cycloaddition of permanganate, as opposed to historical mechanisms of attack of the sulfur atom by one O or by Mn. Such a mechanism, reminiscent of ozonolysis, may prevail in most permanganate oxidations. The ab initio activation enthalpies are in reasonable agreement with the experimental data; the ab initio activation entropies are not, possibly because of problems with Eyring equation assumptions.     

Asymmetric synthesis of 4,4-disubstituted 2-cyclopentenones from optically active 1-chlorovinyl p-tolyl sulfoxides and cyanomethyllithium with formation of a quaternary chiral center

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides having two different substituents at the 2-position, which were synthesized from unsymmetrical ketones and (R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with cyanomethyllithium gave optically active 2-amino-1-cyano-5,5-disubstituted-1,3-cyclopentadienes with very high asymmetric induction from the sulfoxide chiral center. The products were converted to the enantiomerically pure 4,4-disubstituted 2-cyclopentenones by heating with phosphoric acid in acetic acid.     

Studies on the Pauson–Khand reaction of alkynyl sulfoxides. Unexpectedly easy racemization of their dicobalt hexacarbonyl complexes

The scope and limitations of the Pauson–Khand reactions of alkynyl sulfoxides with strained alkenes have been studied. (S)-1-Hexynyl p-tolyl sulfoxide and (S)-2-phenylethynyl p-tolyl sulfoxide afforded β-(p-tolylsulfinyl)enones in moderate yields and low diastereoselectivities. The diastereomeric mixtures were easily separated by column chromatography and the sulfinyl group could be cleaved by a sequence involving reduction to sulfide, carbonyl reduction and enol thioether hydrolysis to afford 1,3-rearranged enantiomerically enriched α-butyl and α-phenyl enones. The absolute configuration of the Pauson–Khand adducts was determined by X-ray diffraction. The decreased enantiomeric excess of the final products uncovered an unprecedented low temperature racemization of the hexacarbonyl dicobalt complexes of alkynyl sulfoxides.