Propargyl Sulfides Research Articles

Palladium‐Catalyzed Preparation of Propargylic or Allenylic Sulfides from Propargyl Halides or Mesylate and Thiols

AbstractIn the presence of a catalytic amount of Pd0‐dppe complex [dppe: 1,2‐bis(diphenylphosphanyl)ethane], generated in situ from [Pd2(dba)3·CHCl3] and dppe, propargylic bromide 1a reacted with an equimolar amount of propanethiol at 60 °C in DMF to afford propargylic sulfide 2 in an excellent yield. The reaction occurs readily when carried out in the presence of the weak base triethylamine. The choice of both the phosphane, which is employed as the palladium atom’s ligand, and the solvent have a remarkable effect on this reaction. We found that the optimum conditions for the reaction are those using a bidentate phosphane ligand (dppe) in a polar solvent (DMF). Compound 1a reacted smoothly with both aromatic (PhSH) and secondary thiols (CySH) in high yields. The reactions with thiols bearing functional groups (OH or Cl) proceeded selectively in good to moderate yields. Primary chlorides 1b−e were readily converted into their corresponding propargylic sulfides 7−10 in high yields. The Pd0‐dppe catalyst was ineffective in the reaction of the bromide 1g bearing a tBu group at the propargylic position, but the reaction of the corresponding mesylate 1h using the Pd0‐DIOP catalyst [DIOP = O‐isopropylidene‐2,3‐dihydroxy‐1,4‐bis(diphenylphosphanyl)butane] at 100 °C afforded the product 11 in good yield. Allenylic sulfides were obtained from 1g−i. We suggest that a cationic η3‐type complex may be a more reactive intermediate in this catalytic reaction than neutral η1‐ or η3‐allenyl/propargylpalladium complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Iron(II)‐Catalyzed Sulfimidation and [2,3]‐Sigmatropic Rearrangement of Propargyl Sulfides with tert‐Butoxycarbonyl Azide. Access to N‐Allenylsulfenimides.

The iron(II)-catalyzed Bach reaction of tert-butoxycarbonyl azide (BocN(3)) and allyl sulfides has been extended to include propargyl sulfides, which give N-allenylsulfenimide products. Using 10 mol % dppeFeCl(2) as catalyst the reaction proceeds at 0 degrees C with a number of different propargyl sulfides in 31-73% isolated yield. The reaction is limited by product instability toward catalyst and termination of the catalytic cycle by excess BocN(3). N-Allenylsulfenimide 2b smoothly undergoes catalytic hydrogenation and a Diels-Alder reaction with cyclopentadiene.

Ruthenium‐Catalyzed Propargylic Substitution Reaction of Propargylic Alcohols with Thiols: A General Synthetic Route to Propargylic Sulfides.

A novel cationic methanethiolate-bridged diruthenium complex [Cp*RuCl(μ2-SMe)2RuCp*(OH2)]OTf (1e) has been disclosed to promote the catalytic propargylic substitution reaction of propargylic alcohols bearing not only terminal alkyne group but also internal alkyne group with thiols. It is noteworthy that neutral thiolate-bridged diruthenium complexes (1a−1c), which were known to promote the propargylic substitution reactions of propargylic alcohols bearing a terminal alkyne group with various heteroatom- and carbon-centered nucleophiles, did not work at all. The catalytic reaction described here provides a general and environmentally friendly preparative method for propargylic sulfides, which are quite useful intermediates in organic synthesis, directly from the corresponding propargylic alcohols and thiols.

1,2‐Migration of the Thio Group in Allenyl Sulfides: Efficient Synthesis of 3‐Thio‐Substituted Furans and Pyrroles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Iron(II)-catalyzed sulfimidation and [2,3]-sigmatropic rearrangement of propargyl sulfides with tert-butoxycarbonyl azide. Access to N-allenylsulfenimides.

The iron(II)-catalyzed Bach reaction of tert-butoxycarbonyl azide (BocN(3)) and allyl sulfides has been extended to include propargyl sulfides, which give N-allenylsulfenimide products. Using 10 mol % dppeFeCl(2) as catalyst the reaction proceeds at 0 degrees C with a number of different propargyl sulfides in 31-73% isolated yield. The reaction is limited by product instability toward catalyst and termination of the catalytic cycle by excess BocN(3). N-Allenylsulfenimide 2b smoothly undergoes catalytic hydrogenation and a Diels-Alder reaction with cyclopentadiene.

Catalytic asymmetric [2,3] sigmatropic rearrangement of sulfur ylides generated from carbenoids and propargyl sulfides

Catalytic asymmetric [2,3] sigmatropic rearrangement of sulfur ylides generated from aryldiazoacetates and propargyl sulfides with a number of chiral Rh(II) and Cu(I) catalysts have been investigated and moderately high enantioselectivities (up to 81% ee) have been achieved.

Electrolytic partial fluorination of organic compounds. 64.(1) Anodic mono- and difluorination of thiazolyl sulfides.

The anodic fluorination of 2-thiazolyl methyl sulfide, 2-thiazolyl propargyl sulfide, and 2-thiazolyl acetonyl sulfide was successfully carried out to provide the corresponding 5-fluorothiazole and 2,5,5-trifluorothiazoline derivatives. The latter products were readily hydrolyzed to give isolable 5,5-difluoro-2-hydroxythiazoline derivatives. On the other hand, anodic fluorination of 2-thiazolyl cyanomethyl sulfide afforded 5-fluorothiazole and alpha-fluorinated thiazole derivatives. Thus, the product selectivity was found to be greatly changed by the electron-withdrawing ability of substituents at the side chain of the thiazole ring. This is the first report of a successful anodic fluorination of a thiazole ring.

Ruthenium-catalyzed propargylic substitution reaction of propargylic alcohols with thiols: a general synthetic route to propargylic sulfides.

A novel cationic methanethiolate-bridged diruthenium complex [Cp*RuCl(mu2-SMe)2RuCp*(OH2)]OTf (1e) has been disclosed to promote the catalytic propargylic substitution reaction of propargylic alcohols bearing not only terminal alkyne group but also internal alkyne group with thiols. It is noteworthy that neutral thiolate-bridged diruthenium complexes (1a-1c), which were known to promote the propargylic substitution reactions of propargylic alcohols bearing a terminal alkyne group with various heteroatom- and carbon-centered nucleophiles, did not work at all. The catalytic reaction described here provides a general and environmentally friendly preparative method for propargylic sulfides, which are quite useful intermediates in organic synthesis, directly from the corresponding propargylic alcohols and thiols.

Electrolytic Partial Fluorination of Organic Compounds. Part 60. Highly Regioselective Anodic Fluorination of Aryl Propargyl Sulfides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Base-Catalyzed Reactivity of Sulfur- and Selenium-Bridged Cyclic Alkynes: Tandem Isomerization and Cycloaromatization versus Isomerization and Nucleophilic Addition

The synthesis and base-catalyzed reactivity of some novel sulfur- and selenium-bridged cyclic di- and tetralkynes, derived from 1,2- and 1,4-dihydroxybenzene and 1,2-bis(bromomethyl)benzene, are described. The cyclic propargylic sulfides and selenides undergo base-induced isomerization to the corresponding allenes, followed by cycloaromatization of the latter by diradical or anionic mechanisms, depending on the nature of the base. Because of the lack of stability of the expected diradical intermediate, the corresponding allenic sulfones undergo nucleophilic addition, which is responsible for their DNA-cleaving properties. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Electrolytic partial fluorination of organic compounds. Part 60: Highly regioselective anodic fluorination of aryl propargyl sulfides

Aryl propargyl sulfides were subjected to electrochemical fluorination in dimethoxyethane (DME) containing various fluoride supporting electrolytes using an undivided cell to provide the corresponding α-monofluorinated or α,α-difluorinated sulfides selectively as main products in good yields depending on the amount of electricity passed. The α,α-difluorinated sulfides were stable enough to be isolated while the α-monofluorinated ones were very unstable. The α-monofluorinated sulfides were readily converted into the corresponding stable α-monofluoroallenyl sulfides in good yields. Furthermore, synthetic utility of α-monofluoroallenyl sulfides was also investigated.

ChemInform Abstract: Electrolytic Partial Fluorination of Organic Compounds. Part 57. Regioselective Anodic Monofluorination of Nitrogen‐Containing Heterocyclic Propargyl Sulfides.

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Selective oxidation of allylic sulfides by hydrogen peroxide with the trirutile-type solid oxide catalyst LiNbMoO(6).

Chemoselective sulfur oxidation of allylic sulfides containing double bonds of high electron density due to multiple alkyl substituents or extended conjugation was developed using the composite metal oxide catalyst, LiNbMoO(6), without any epoxidation of the electron-rich double bond(s). Selective oxidation to either the corresponding sulfoxides or the sulfones was realized by controlling the stoichiometry of the quantitative oxidant, H(2)O(2). This new oxidant system had general applicability for chemoselective oxidation of various allylic, benzylic, or propargylic sulfides containing unsaturated carbon-carbon bonds with different electron properties. Various functional groups including hydroxy, formyl, and ethers of THP or TBDMS are compatible under this mild oxidation reaction condition.

Electrolytic partial fluorination of organic compounds. Part 57: Regioselective anodic monofluorination of nitrogen-containing heterocyclic propargyl sulfides

Anodic fluorination of various nitrogen-containing heterocyclic propargyl sulfides using Et4NF·nHF (n=3,4) or Et3N·3HF as a supporting electrolyte and fluoride ion source in dimethoxyethane provided the corresponding monofluorinated products in moderate yields. Fluorination took place selectively at the position α to the sulfur atom of the sulfides and the heterocyclic moieties were not fluorinated at all.

Electrolytic Partial Fluorination of Organic Compounds. Part 43. Highly Regioselective Anodic Mono‐ and Difluorination of Propargyl Sulfides and Preparation of α‐Fluoroallenyl Sulfides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Electrolytic partial fluorination of organic compounds. Part 43: Highly regioselective anodic mono- and difluorination of propargyl sulfides and preparation of α-fluoroallenyl sulfides

The anodic fluorination of aryl propargyl sulfides in DME containing a fluoride supporting electrolyte using an undivided cell provided the corresponding α-mono- and α,α-difluorinated sulfides selectively, depending on the amount of electricity passed. The α-monofluorinated sulfides were readily converted into the corresponding α-fluoroallenyl sulfides in good to moderate yields.

Flash Vacuum Thermolysis – Synthesis and Characterization of Unstabilized Cycloalkenethiones

The flash vacuum thermolysis (FVT) of cycloalkenyl allyl (or propargyl) sulfides 8, 9, 12, and 13 led, as the main thermal pathway, to the conjugated cycloalkenethiones 1, 3, and 5, resulting from a retro-ene reaction. These reactive thioketones, thus obtained in ca. 70% yield, have been characterized in the gas phase by mass spectrometry, and at low temperature by IR, UV/Vis and NMR spectroscopy. The polymerization of 1, 3, and 5 upon warming is generally more rapid than the other attempted reactions and only the [2 + 3] dipolar cycloaddition with diazomethane led in low yield, besides polymeric materials, to isomeric 1,3-dithiolanes 20 from cyclopentenethione 1. The obtention of the nonconjugated cycloalkenethiones 2 and 4, expected in the FVT of sulfides 10 and 11, has been confirmed only by UV/Vis spectroscopy at –196 °C, due to their rapid enethiolization. In the case of the large-ring sulfide 14, the (E) geometry of the double bond favoured the competitive retro-ene reaction yielding cyclododecene and propynethial; on the other hand, the FVT of the tricyclic gem-dithiol 15, a possible precursor of cyclobutenethione (7), led to vinyl thioketene (18), obtained by thermal ring opening of 7.

Preparation of benzo[b]thiophenes by Pd(0)-catalyzed intramolecular cyclization of allyl (and propargyl) o-iodophenyl sulfides.

Benzo[b]thiophenes are prepared by intramolecular Pd(0)-catalyzed Heck reaction of allyl o-iodophenyl sulfides. Pd(0)-Catalyzed intramolecular cyclization of o-iodophenyl propargyl sulfide in the presence of a hydride donor gives 3-methylene-2,3-dihydrobenzo[b]thiophene, which reacts with several enophiles in ene type reactions. However, allyl (and propargyl) aryl sulfides react with palladium(II) chloride to afford polymeric [PdCl(SAr)] 2.

ChemInform Abstract: New Entry to the Perhydrofuro(2,3‐b)furan Ring System.

AbstractThe unsaturated diazo diesters (II), prepared from phenyl propargyl sulfide (I) via reaction with epoxides and malonic acid monoethyl ester, undergo Rh(II)‐catalyzed denitrogenation and ring closure to produce a mixture of the valerolactones (III) and (IV).

ChemInform Abstract: Stereoselective Synthesis of Contiguously‐Substituted Butyrolactones Based on the Cyclic Allylsulfonium Ylide Rearrangement.

AbstractPhenyl propargyl sulfide (I) is activated via formation of the ethyl Grignard compound to react with the aldehydes (II), forming the carbinols (III) which are O‐acylated with ethyl malonyl chloride (IV) to give the esters (V).