Allylic phenyl sulfides

Parallel and reversible reactions. The isomerization of allyl phenyl sulfide is a degenerate rearrangement made detectable by isotopic labeling of one end of the allyl group, permitting kinetic monitoring by NMR techniques.12... 

In an analogous process, the reactions of unsubstituted and 2-substituted allyl phenyl sulfides with (TMSlsSiH give a facile entry to allyl fns(trimethylsilyl) silanes in high yields (Reaction 26). In this case, the addition of (TMSlsSi radical to the double bond is followed by the S-scission with ejection of a thiyl radical, thus affording the transposed double bond. Hydrogen abstraction from (TMSlsSiH by PhS radical completes the cycle of these chain reactions. ... 

As has been described for allyl bromide (see preceding paragraph), allyl sulfides and allyl phenyl selenide react with 6-diazopenicillanates 134 under Cu(acac)2 catalysis to give the products of ylide formation and subsequent [2,3] rearrangement 155-159). Both C-6 epimers are formed. The yields are better than with BF3 Et20 catalysis, and, in contrast to the Lewis acid case, no 6[Pg.139]

Allyl tris(trimethylsilyl)silanes are obtained in high yields from the reactions of unsubstituted and 2-substituted allyl phenyl sulfides with (TMS)3SiH... 

Divalent sulfur is a poison for most noble metal catalysts so that catalytic hydrogenation of sulfur-containing compounds poses serious problems (p. 10). However, allyl phenyl sulfide was hydrogenated over tris trisphenyl-phosphine)rhodium chloride in benzene to give 93% yield of phenyl propyl sulfide [674. ... 

Thiochroman (1 R = Ha) is a product of the thio-Claisen rearrangement of allyl phenyl sulfide, as reported in 1963 27 this reaction also produces 2,3-dihydrothiophenes as shown in Eqs. (6) and (7).28,29... 

Reductive lithiation of allyl phenyl sulfides.1 This reagent is particularly useful for preparation of allyllithium reagents at temperatures at which the anions are stable. Moreover, regioselectivity in reactions can be achieved by conversion to allyltitanium(IV) complexes by metal exchange with Ti(0-/-Pr)4. Thus the un-symmetrical anion formed from the allyl sulfide 1 with LDMAN reacts with cro-tonaldehyde to give a mixture of 1,2- and 1,4-adducts. The 1,2-adduct 2 can be obtained in high yield as two diastereomers (9 1) by use of the allyltitanium complex (equation I). 

Alternatively, the ambident oi-hetero substituted allyl anions have been utilized as homoenolate equivalents. For example, in the presence of HMPA, allyl phenyl sulfides (251),192 allyl phenyl sulfones (252)192b c and allyl phenyl selenides (253)192d e add to a,(3-enones in a l,4(0)-mode, while allyl phenyl sulfoxides (254) and allyl phosphine oxides (255) afford 1 A j-addition exclusively, irrespective of solvent used.193 Hua has shown that additions of either chiral sulfoxide (254 R1 = R2 = R3 = R4 = H, R5 = p-tolyl) or allyl oxazaphospholidine oxide (256) occur with excellent enantioselectivity (>95% ee).194 Similarly, Ahlbrecht reports that the a-azaallyl (257) adds exclusively in a 1 A j-mode to acceptor (59) to afford 1,5-diketones (Scheme 86).195... 

Methylidenation of allylic thioethers. Methylidenation of an allylic phenyl-thioether with methylene iodide-diethylzinc is accompanied by a 2,3-sigmatropic rearrangement to a homologous allylic phenylthioether. The rearrangement is also initiated by ethylidene iodide. Cyclopropanation is not observed. The Simmons-Smith reaction with allylic sulfides results only in formation of an insoluble polymer. 

A convenient method for the selective oxidation of oximes to carbonyl compounds using A-bromo-A-benzoyl-4-toluenesulfonamide is reported.172 A convenient method for the preparation of 2-phenylthio-3-bromopropene by bromination of allyl phenyl sulfide is shown to proceed via the formation of a l,3-dibromo-2-(phenylthio)propane intermediate.173... 

The reductive metallation of aryl sulfides allows the preparation of organolithium compounds. Cohen showed that soluble Mg-anthracene complex can be used instead of Li-naphthalenide for the reductive metallation of allyl phenyl sulfides (Scheme 5).15... 

Diphenyl sulfide was converted to benzene over Re2S7 in ethanol at 300°C.173 However, thioethers appear to be stable at the temperatures of 155-245°C over Re2S7, since hydrogenation of allyl phenyl sulfide and thiophene over Re2S7 affords exclusively propyl phenyl sulfide at 150-160°C and thiolane at 230-260°C, respectively (eq. 13.98).173... 

We also observed similar phenomena in the reaction of silyl enol ethers with cation radicals derived from allylic sulfides. For example, oxidation of allyl phenyl sulfide (3) with ammonium hexanitratocerate (CAN) in the presence of silyl enol ether 4 gave a-phenylthio-Y,5-un-saturated ketone 5. In this reaction, silyl enol ether 4 reacts with cation radical of allyl phenyl sulfide CR3 to give sulfonium intermediate C3, and successive deprotonation and [2,3]-Wittig rearrangement affords a-phenylthio-Y,6-unsaturated ketone 5 (Scheme 2). Direct carbon-carbon bond formation is so difficult that nucleophiles attack the heteroatom of the cation radicals. 

In 2000 this work was extended by a systematic screening of the influence of the S-bound substituent [229]. It was found that replacing the S-phenyl group in allyl phenyl sulfide with 2,6-dimethylphenyl increases the ee of the major diastereomer from 14 to 52% in CuVbisoxazoline-catalyzed rearrangements. 

Hydrogen peroxide attacks the sulfur atom in preference to the double bond in allyl phenyl sulfide and allyl benzyl sulfide to give allyl phenyl sulfoxide (64%) and allyl benzyl sulfone (85%), respectively. Olefinic sulfones may also be obtained by dehydrohalogenation of /3-haloalkyl sulfones prepared by this method. Oxidation of sulfides has been utilized in the preparation of sulfones containing other common functional groups such as the amide, tro, amino, and ester groups. 

During the oxidative addition of allylic phenyl sulfides to palladium(0) complexes to give / -allyl-/ -sulfide complexes, 41 (R -R = H or Me, R H, Me, or Ph), reactants having y substituents (R or R ) require more than 20 times as long for completion of the reactions than those with either no or a or substituents. The reaction, therefore, probably occurs by initial electrophilic attack by the palladium on C-y, expulsion of the SPh unit, and formation of a metal-metal bond (63). 

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