Phenylsulfenyl

The intermediacy of zwitterionic species was proposed for the addition of phenylsulfenyl chloride to dimethylaminomethyl-substituted enamines (465,466). They receive support from the observed lack of stereospecific addition of methylsulfonyl chloride to cw-morpholinopropene (although the trans enamine gives only one adduct) (466). 

Photolytic cleavage reactions (e.g., of o-nitrobenzyl, phenacyl, and nitro-phenylsulfenyl derivatives) take place in high yield on irradiation of the protected compound for a few hours at 254-350 nm. For example, the o-nitrobenzyl group, used to protect alcohols, amines,and carboxylic acids, has been removed by irradiation. Protective groups that have been removed by photolysis are described at the appropriate places in this book in addition, the reader may wish to consult five review articles. 

A -Hydroxybenzotriazole, trifluoroethanol, rt." Trityl and Nps (2-nitro-phenylsulfenyl) groups are also cleaved under these conditions. 

PHENYLSULFENYLATION OF NONACTIVATED 6-CARBON ATOM BY PHOTOLYSIS OF ALKYL BENZENESULFENATES PREPARATION OF 2-PHENYLTHIO-5-HEPTANOL... 

Phenylsulfenylation is also conceivable in a tin-free variant however, when alkyl benzenesulfenates were irradiated in the absence of hexabutylditin, the reaction proceeded at a lower rate and gave 10-15% lower yields of 5-phenylthio alcohols.6... 

The procedure of phenylsulfenylation of 5-carbon atom was applied to a variety of other substrates as summarized in Table 1. 

In their work concerning the anions derived from chiral phosphonamidates, Denmark and Chen [68] obtain a high diasteromeric excess of 88% for the compound 108 resulting from the addition of the carbanion of phenylsulfenyl phos-phonamidate 107 to 4-terf-butylcyclohexanone (Scheme 31). 

Attempts to replace the phenylsulfenyl group in 1239 with benzyloxytrimethyl-silane 13 c leads, via fragmentation of 1240 and 1241 and incorporation of acetonitrile in a Ritter reaction, to 82% of a 7 1 mixture of 1242 and 1243 [44]... 

Compared to a bromonium ion, the C-S bonds are stronger and the TS for nucleophilic addition is reached later. This is especially true for the sulfurane structures. Steric interactions that influence access by the nucleophile are a more important factor in determining the direction of addition. For reactions involving phenylsulfenyl chloride or methylsulfenyl chloride, the intermediate is a fairly stable species and ease of approach by the nucleophile is the major factor in determining the direction of ring opening. In these cases, the product has the anti-Markovnikov orientation.62... 

Several examples of sulfenylcyclization are given in Section A of Scheme 4.5. Entry 1 is a 6-exo sulfenoetherification induced by phenylsulfenyl chloride. Entry 2... 

Another domino process starting with a [2,3] sigma tropic rearrangement allows transformation of the propargylic alcohol 4-315 into the conjugated tetraenes 4-316 on treatment with phenylsulfenyl chloride, as described by Lera and coworkers (Scheme 4.69) [107]. 

A new stable sulfenylating reagent 3-phenylsulfenyl-2-GV-cyano-imino)thiazolidine 57 has been described. It reacts with amines or thiols to give sulfenamides or disulfides in excellent yields. a-Sulfenylation of carbonyl compounds also proceeds smoothly and if an optically active 4-diphenylmethyl substituent is attached to the thiazolidine ring (58), the cyclic (3-ketoester 59 can be sulfenylated in high yield with an ee of 96% to give the sulfide 60 <00SL32>. 

Carbosulfenylation of alkenes. This organotitanium reagent reacts with the trans-p-chloro sulfide 2a, formed by addition of phenylsulfenyl chloride to cyclo-... 

It was found that PhSOTf is superior to MeSOTf in terms of both yield and stereoselectivity of sialylation, especially when applied in combination with the hindered base 2,6-di(tert-butyl)-pyridine (DTBP) at low temperatures (—70 °C) [410]. Promoter was generated by the reaction of phenylsulfenyl chloride (PhSCl)... 

Cutting and Parsons described the transformation of acetylenic alcohols 314 into allenyl phenyl thioethers 316 by a two-step procedure (Scheme 8.85) [174], Deprotonation of alkynes 314 with n-butyllithium is followed by addition of phenylsulfenyl chloride, forming sulfenyloxy intermediates which subsequently rearrange to allenic sulfoxides 315. Treatment of allenes 315 with methyllithium results in loss of the sulfoxide moiety to form allenyl sulfides 316 in reasonable yields. 

W Kessler, B Iselin. Selective deprotection of substituted phenylsulfenyl protecting groups in peptide synthesis. Helv Chim Acta 49, 1330, 1966. 

Anodic regioselective fluorination of a-phenylsulphenylated ethyl acetates, 1-naphthalene and 2-pyridine derivatives [80], l-aryl-3-(phenylthio)oxindoles and 2-substituted-3-oxo-4-(phenylthio)-l, 2, 3,4-tetrahydroisoquinolines [81], 2-benzo-thiazolyl and 5-chloro-2-benzothiazolyl sulfides [82], a-(phenylsulfenyl)lactams [83], as well as various heterocycles such as thiolanones, oxathiolanones, dithi-olanones, 3Fl-l,4-benzoxathian-2-ones [84] in Et3N-3HF or Etr NF- HF [n = 3,4), has been reported. 

Phenylsulfenyl fluoride was detected by F-NMR in the reaction mixture during the conversion of diphenyl disulflde into thianthrene using SF4(78MII). 

Phenylsulfenyl chloride decomposes rapidly In moist air, and should be handled and stored under dry nitrogen. 

The submitters preferred to transfer the phenylsulfenyl chloride via cannula. The sodium nitromethane-ethanol slurry Is added by attaching the Erlenmeyer flask containing it to the reaction flask via an angle adapter and then simply inverting the Erlenmeyer flask. In either method additional absolute ethanol may be necessary to complete the latter addition. 

Sodium nltromethylate Methane, n1tro-, lon(l-). sodium (8,9) (25854-38-0) Phenylsulfenyl choride Benzenesulfenyl chloride (8,9) (931-59-9) Nltromethane Methane, nitro- (8,9) (75-52-5)... 

The stereospecific anti addition of phenylsulfenyl chloride to norbomene is a particularly interesting example of the stability of the intermediate. Neither rearrangement nor syn addition products, which are observed with many of the other electrophilic reagents, are formed.63 This result indicates that the intermediate must be quite stable and reacts only by nucleophilic attack.64... 

Funabiki prepared a-fluoro-/ -phenylacrylaladehyde (92), a particularly useful synthetic intermediate, by an addition elimination strategy (Scheme 34) [81], Electrochemical fluorination of //-phenylsulfenyl-a, S-unsaturated ketones can form a-fluoro-a, S-unsaturated carbonyl compounds (Scheme 35) [82], a-Fluoro- S-thio-a, S-unsaturated ketone (93) was synthesized by the selective nucleophilic... 

An intramolecular regioselective sulfenocyclization of unsaturated ureas 447 resulted in formation of 5,6-dihydro-4//-l,3-oxazine derivatives 449 (Scheme 86). The procedure employed phenylsulfenyl chloride and ethyldiisopro-pylamine to generate an episulfonium ion intermediate 448, from which the cyclic products 449 were formed by internal nucleophilic displacement <1995M609>. 

T. Kondo, H. Abe, and T. Goto, Efficient synthesis of 2a-glycoside of W-acetylneuraminic acid via phenylsulfenyl chloride adduct of 2-deoxy-2,3-dehydro-lV-acetylneuraminic acid methyl esier tetra-O-acetate, Chem. Lett., p. 1657 (1988). 

New examples of application appear regularly. In the following one [248] phenylsulfenylation of nopinone (4) was followed by oxidation to the sulfoxide. Pummerer rearrangement of the latter led directly to the a-phenylthio substituted a-unsaturated ketone (6) (overall yield 94%), starting material for further elaboration of natural sesquiterpene synthesis via 4,4-disubstituted nopinones (7). 

One example of oxetane formation proceeding by an intramolecular syn addition of a sulfenate ester intermediate has been reported (equation 5).16 This mode of cyclofunctionalization appears to fail unless the substrate enforces the correct alignment of the sulfenate ester.16b However, related 7-oxanorbomen-2-ols give oxetane products with an exo phenylsulfenyl group.17... 

The cyclization of carbamate derivatives of unsaturated amines has proven synthetically useful. Cyclizations of carbamates of allylamines containing a terminal vinyl group give oxazolidinone products (equation 60 and Table 17, entries 1 and 2).99,161 Bromocyclizations of systems with a di- or tri-sub-stituted alkene often give mixtures of oxazolidinones and tetrahydrooxazinones,163 while cyclization of an A -cinnamyl carbamate with phenylsulfenyl chloride gave only the oxazolidinone product.163b,163c The stereochemistry of the cyclization of primary carbamates of either allylic or homoallylic amines is low... 

The diastereoselectivity in 5-exo cyclization of a range of chiral acyl radical equivalents derived from 1,3-dioxolanes and dioxanes has been investigated. Results indicate that selectivity was poor for radicals which cyclised via a twist-boat conformation but high when l,3-dioan-2-yl radicals containing an imposed chair-like conformation were used.173 The 5-exo cyclizations of a-phenylsulfenyl radicals,... 

Disubstituted [S-lactams have been obtained with high trans diastereoselection in the reaction between /V-phenylsulfenyl imines, as nucleophilic partners in the Staudinger reaction, and acetoxyacetyl chloride (Scheme 42), [117]. 

Ethynylation of the ketone 1 and treatment of the propargyl alcohol thus obtained with phenylsulfenyl chloride in the presence of triethylamine gave the expected allene sulfoxide. Treatment of this sulfoxide with aluminium trichloride in benzene gave the sulfide 2 in 15% yield. 

Intermediate 3 can either be isolated or used in situ for further elaboration. Fluoride-5 and Lewis-acid catalyzed aldol reactions cleanly give aldol adducts,5 and the reaction with phenylsulfenyl chloride gives a-phenylthio ketones in high yield.5... 

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