Structures sulfenylation

The free-radical chemistry of fluoroalkanesulfenyl chlorides with hydrocarbons was also investigated [S, 9], Depending upon the structures of the sulfenyl chloride and the hydrocarbon, these reactions yield as major products up to three of the following four types of organic compounds thiols, disulfides, sulfides, and chlorohydrocarbons (equation 6), Perfluoroisobutanesulfenyl chloride is unique m that the only major products detected are the thiol and chlorohydrocarbon [ ] (equation 6) (Table 3). 

The first structure determination on a sulfenyl iodide was that of thermally labile Ph3CSI. 

Thiolsulfonates have the structure shown in [58]. That they may be considered the mixed anhydride of a sulfenic and a sulfinic acid is indicated by one of the principal synthetic methods for their preparation, namely reaction (166) of a sulfinic acid with a sulfenyl chloride (Stirling, 1957). Once again, as we have... 

Mechanistic studies have been most thorough with the sulfenyl halides.63 The reactions show moderate sensitivity to alkene structure, with electron-releasing groups on the alkene accelerating the reaction. The addition can occur in either the Markownikoff or anti-Markownikoff sense.64 The variation in regioselectivity can be understood by... 

The sulfur derivatives of methylcarbamate insecticides which have been described are those containing a sulfenyl (or thio) sulfur attached to the methylcarbamate nitrogen atom. N-Alkylsulfinyl or N-aryIsulfinyl derivatives (general structure... 

The sulfenyl phthalimides are one of the oldest groups of fungicides and are effective, safe and persistent (B-77MI10706). Captan (59) is cheaply made from the Diels-Alder adduct of butadiene and maleic anhydride, followed by conversion to the imide and reaction with trichloromethanesulfenyl chloride. Folpet (60) and captafol (61) are similar in structure. 

Compound 35, along with some other structurally related sulfenylating agents, has also been found to be useful for the functionalization of 1,3-dicarbonyl compounds 38 (Eq. 9). Lactones and / -dicarbonyl compounds were a-sulfenylated in the presence of (DHQD)2PYR in high yields and moderate to good enantioselec-tivities (51-91% ee) [34]. 

Although sulfur forms a variety of structures differing in the number of ligands and valency, the overwhelming majority of stereoselective C-S bond forming reactions are limited to those which afford chiral carbon compounds with the sulfenyl, sulfinyl and sulfonyl moieties bonded to the stereogenic carbon atom. In accord with this, discussion of stereoselective C—S bond formation will be divided into three corresponding subsections. Procedures with stereoselective C—S bond formation where the sulfur is in a less common form are also presented. 

Vinyl sulfides have been prepared by the catalytic addition of the S—H bond of thiols (85) to terminal alkynes (86) under solvent-free conditions using the nickel complex Ni(acac)2 (47). High alkyne conversions (up to 99%) were achieved after 30 min at 40 °C in favor of the corresponding Markovnikov products (87) (equation 23). Other metal acetylacetonate complexes were examined for this reaction, but none showed any improvement over the nickel catalyst. Mechanistic details suggest that alkyne insertion into the Ni—S bond is important to the catalytic cycle and that nanosized structural units comprised of [Ni(SAr)2] represent the active form of the catalyst. Isothiocyanates and vinyl sulfides have been produced in related Rh(acac)(H2C=CH2)2 (6) and VO(acac)2 (35) catalyzed sulfenylation reactions of aryl cyanides and aryl acetylenes, respectively. 

Treatment of a number of substituted allylic alcohols 102 with morpholino sulfenyl chloride 103 at low temperature led to the formation of amidosulfoxy-lates 104, which rearranged readily during warm up to room temperature. In accordance with the proposed transition-state structures for [2,3]-sigmatropic rearrangements [6,40], the double bond geometry in 105 was found to be E for all cases with = H, CH3 (with a decreased selectivity for some functionalized... 

MO calculations have been carried out on the isomerization of cyclopropane to propene, and the MNDO method has been used to study the reaction pathway and to optimize the structure of reactant, transition structure, and product of the ring opening reaction of bicyclo[1.1.0]butane. Various methods have been employed to estimate the rate constants for ring opening of the 2-cyclopropyl-2-propyl radical. 1-Acceptor-1-sulfenyl-substituted 2-vinylcyclopropanes of the type (430) have been found to afford 6-sulfenyl-a,jS y, -unsaturated carboxylic esters and nitriles (431) upon treatment with acid, by a process which involves C(l)—C(2) bond fission and a novel 1,5-sulfenyl rearrangement (see Scheme 110). It has been shown that the benzophenone-sensitized photolysis of vinyl norcaradiene derivatives, such as 5-(2-methylprop-l-enyl)-3-oxatricyclo[4.4.0.0 ]deca-7,9-dien-4-ones (432), results in the regioselective cleavage of only one of the cyclopropyl c-bonds to afford isochroman-3-one derivatives (433). It has been reported that the major product obtained from the reaction of structurally diverse a-diazo ketones with an electron-rich alkene in the... 

The pJCt value for 2-CHz of 1,3-dithiane is 31.1, indicating that the sulfenyl group stabilizes the adjacent carbanion. Theoretical studies present convincing evidence for the unimportance of d-orbital participation in the acidification of C—H bonds a to sulfur atoms. Whether or not 3d-orbitals are included in Ae basis set, the preferred conformation of CH2 H is predicted to be that of an sp carbanion (2). The calculation, NMR studies and crystallography all support a tetrahedral structure for the a-lithiated sulfide. ... 

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