Aryl allyl sulfides

Finally, Katsuki and coworkers [271] described an enantioselective Ru-catalyzed domino reaction, which includes a sulfamidation of an aryl allyl sulfide 6/3-111 using the chiral Ru(salen)-complex 6/3-115, followed by a 2,3-sigmatropic rearrangement of the formed 6/3-112 to give N-allyl-N-arylthiotoluenesulfonamides 6/3-113. On hydrolysis, 6/3-113 yielded N-allyltoluenesulfonamides 6/3-114 (Scheme 6/3.33). The enantioselectivity ranged from 78 to 83% ee. 

Various S-nucleophiles are allylated. Allylic acetates or carbonates react with thiols or trimethylsilyl sulfide (353) to give the allylic sulfide 354[222], Allyl sulfides are prepared by Pd-catalyzed allylic rearrangement of the dithio-carbonate 355 with elimination of COS under mild conditions. The benzyl alkyl sulfide 357 can be prepared from the dithiocarbonate 356 at 65 C[223,224], The allyl aryl sufide 359 is prepared by the reaction of an allylic carbonate with the aromatic thiol 358 by use of dppb under neutral condi-tions[225]. The O-allyl phosphoro- or phosphonothionate 360 undergoes the thiono thiolo allylic rearrangement (from 0-allyl to S -allyl rearrangement) to afford 361 and 362 at 130 C[226],... 

A possible reaction mechanism shown in Scheme 7-10 includes (a) oxidative addition of the S-H bond to Pd(0), (b) insertion of the allene into the Pd-H bond to form the tt-allyl palladium 38, (c) reductive elimination of allyl sulfide, (d) oxidative addition of the I-aryl bond into the Pd(0), (e) insertion of CO into the Pd-C bond, (f) insertion of the tethered C=C into the Pd-C(O) bond, and (g) P-elimination to form 37 followed by the formation of [baseHjI and Pd(0). 

Another interesting example of a photochemi-cally induced domino process is the combination of the photocyclization of aryl vinyl sulfides with an intramolecular addition as described by Dittami et al. [901 as intermediate a thiocarbonyl ylide can be assumed. The domino-Norrish I-Knoevenagel-allyl-silane cyclization developed by us allows the efficient stereoselective formation of 1,2-trans-subsituted five- and six-membered carbocycles.1911 A photochemical cycloaddition of enamino-aldehydes and enamino-ketones with the intermediate formation of an iminium salt followed by addition to allylsilanes gives access to novel bicyclic heterocy-des. New examples of photochemically induced... 

The nickel-catalysed reaction of aryl, allyl or vinyl sulfides with Grignard reagents has been found to be an effective way for the conversion of carbon-sulfur bonds into carbon-carbon bonds [318]. However, simple aliphatic substrates are inert. 

Li, Na and K in hydrocarbons, ethereal solvents, HMPA or DMA have been used to desulfurize sul-fides, but applications are limited to simple sulEdes, and particularly to aryl alkyl sulfides. Since these desulfurizations were performed without protic solvent, the organometallics formed may react further and particularly with the solvent. Thus low temperatures were recommended. Potassium graphite (CgK) in excess in ether was also proposed for the desulfurization of allyl or vinyl sulfones, but this reagent is not free of disadvantages. ... 

Competing reactions to addition to a-hetero-substituted alkenes are metallation of vinylic or allylic protons (see 5.5.2.3.2) and cleavage of the carbon-hetero-element bond (see 5.5.2.2.1.). a-Metallations occur with vinylic chlorides, fluorides and ethers no addition of RLi occurs with vinyl fluorides, chlorides or ethers. For vinylic sulfides and selenides, whether metallation or addition (or even carbon-heterobond cleavage) occurs depends on the conditions and reagents. Addition of RLi (R = Et or n-Bu, not Ph) occurs to aryl vinyl sulfides ... 

In 1982, Ueno reported the first uses of allylic sulfur compounds for carrying out the allylation of a carbon-centered radical [48], The reactions detailed are cycliza-tion reactions in which an aryl radical adds to an allylic sulfide to form either an indole or benzofuran product (Scheme 17). Tin, in the form of tributyltin hydride, was used to carry the radical chain. With low concentrations of tin hydride, yields of the desired products as high as 96% were observed. A more recent set of examples of cyclizations onto allylic sulfides was reported by Ward in 1991 [49]. 

The enantioselective C-silylation of allylic substrates such as (V-(terf-butoxycarbonyl)-A(-(p-methoxyphenyl)allylamines or 1,3-diphenylpropene is accomplished with butyUithium in the presence of (—)-sparteine, followed by the addition of TMSOTf (eq 47). The same procedure allows the asymmetric deprotonation-substitution of arenetricarbonyl(O) complexes, while chiral bis(oxazolines) have been the ligands of choice to perform such transformation with aryl benzyl sulfides in these reactions, different yields and enantioselectivities are reached if trimethylsilyl chloride is used as sUylating reagent, although there is a substrate dependence and no definite rules can be established. 

A series of trisubstituted alkenes containing (Z)-allylthio moieties as the key structural units, that is, sodium (Z)-allyl thiosulfates 338, symmetrical di[(Z)-allyl] sulfides 343 and di[(Z)-allyl] disulfides 339 and unsymmetrical diallyl sulfides 341 have been prepared in moderate to good yields via chemical transformations from the acetates of MBH adducts. In addition, it was found that the Sm and a trace amount of I2 could be used for the selective cleavage of the S-S or C-S bonds in sodium (Z)-allyl thiosulfates 338, depending on the substituents (alkyl or aryl group), to give the corresponding... 

The Sharpless epoxidation of allylic alcohols by hydroperoxides uses as mediator [45] or as catalyst [46] a chiral titanium complex obtained from the combination Ti(OPr )4/diethyl tartrate (DET) in 1 1 ratio. Kinetic resolution of P-hydroxysulfides was also observed, but without diastereoselectivity for the product P-hydroxysulfoxides [47]. We found that the Sharpless reagent deactivated by 1 equivalent of water allows the enantioselective oxidation of aryl methyl sulfides into sulfoxides to be performed with ee s up to 90% [4S-50]. The best reagent combination proved to be Ti(0Pr )4/DET/H20 = 1 2 1. Independently, Modena et al. obtained similar enantioselectivities with the combination Ti(OPr )4/DET in 1 4 ratio [51]. These two combinations are sometimes referred to as the Kagan reagent and the Modena reagent, respectively. They will be considered successively. 

Lewis acid, In(0CF3S02)3, catalysed allylic C—H oxidation of aryl cycloalkenes by l-(propyl thio)pyrrolidine-2,5-dione in the presence of CH2CI2 and various nucleophiles (ROH, RCO2H, RSO2NH2) resulted in the formation of allylic ethers, esters, and sulfonamides in 52-83% yields electron-rich substrates were the most reactive. Other aryl cycloalkenes such as 1-naphthyl, l-(3-thiophenyl)-cyclohexene, 1-phenylcycloheptene, and 1-phenylcyclopentene were suitable substrates. Mechanistic studies showed that the sulfenamide played an important role in converting the allyl sulfide intermediate into the products. ... 

A rhodium synthesis of sulfenylated imines containing a quaternary centre has been reported through a denitrogenative [2,3]-sigmatropic rearrangement of 4-aryl-, 4-alkenyl-, and 4-alkyl-A-sulfonyl-l,2,3-triazoles with aryl (alkyl)allyl sulfides (Scheme 57)7 ... 

Nucleophilic Displacement. PhTMS-BF3 0Et2 system has been shown to be useful in the transformation of allylic alcohols to allylic sulfides (eq IS). Preparation of unsymmetrical diaryl sulfides can be achieved by reaction of arenediazonium tetraflu-oroborates with PhSTMS (eq 19). In some cases, addition of cupric sulfide increases the yield of the diaryl sulfides. The use of (phenylthio)trimethylsilane as a coupling partner in palladium catalyzed reactions with aUyl carbonates (eq 20) and aryl iodide (eq 21) has been explored. ... 

The same authors also demonstrated the palladium-catalyzed arylation of in situ generated sulfenate anions, but the catalytic asymmetric conditions provided products 321 with a modest level of enantioselectivity in the presence of Josiphos-like ligands 320. The use of ir-aUylpalladium/ mthenium complexes was also extended to the carbonylation into C S bonds of various allylic sulfides 322 in good to excellent yields by Crudden and Alper. The reaction was... 

Similar to the well-known thio-Claisen rearrangement of allyl aryl sulfides and sulfonium salts, the thio-Claisen rearrangement of allyl aryl sulfoxides has also been reported. For example, heating of allyl 2-naphthyl sulfoxide (147) at 120 °C for 2h in dimethylformamide resulted in quantitative isomerization to the dihydronaphthothio-... 

Scheme 6/3.33. Asymmetric conversion of crotyl aryl sulfides into tV-allyl-arylsulfonamides using a chiral Ru-catalyst.

See also ALKANETHIOLS, ALKENEBIS(SULFONIUM PERCHLORATES) allyl trifluo-ROMETHANESULFONATES, ARENEDIAZO ARYL SULFIDES BIS(ARENEDIAZO) sulfides, BIS(SULFURDIIMIDES DIAZONIUM SULFATES, DIAZONIUM SULFIDES AND DERIVATIVES METAL AMIDOSULFATES, METAL PHOSPHORUS TRISULFIDES METAL SULFATES, METAL SULFIDES, NON-METAL SULFIDES SULFONIC ACID ESTERS, SULFUR BLACK, SULFUR ESTERS THIOPHENOXIDES, XANTHATES ... 

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