Sulfuryl chloride, halogenation

Halogenated Derivatives Slow addition of sulfuryl chloride to acold solution of testosterone acetate (9-1) and pyridine results in formation of the 4-chloro derivative 9-2 (Scheme 5.9). It is likely that the reaction, like many other sulfuryl chloride halogenations, proceeds via a free radical mechanism. 

A more energy-efficient variation of photohalogenation, which has been used since the 1940s to produce chlorinated solvents, is the Kharasch process (45). Ultraviolet radiation is used to photocleave ben2oyl peroxide (see Peroxides and peroxide compounds). The radical products react with sulfuryl chloride (from SO2 and CI2) to Hberate atomic chlorine and initiate a radical chain process in which hydrocarbons become halogenated. Thus, for Ar = aryl,... 

Direct halogenation of sucrose has also been achieved using a combination of DMF—methanesulfonyl chloride (88), sulfuryl chloride—pyridine (89), carbon tetrachloride—triphenylphosphine—pyridine (90), and thionyl chloride—pyridine—1,1,2-trichloroethane (91). Treatment of sucrose with carbon tetrachloride—triphenylphosphine—pyridine at 70°C for 2 h gave 6,6 -dichloro-6,6 -dideoxysucrose in 92% yield. The greater reactivity of the 6 and 6 primary hydroxyl groups has been associated with a bulky halogenating complex formed from triphenylphosphine dihaUde ((CgH )2P=CX2) and pyridine (90). 

The heterocyclic telluride 32 is susceptible to oxidation-addition reactions and readily adds halogen atoms under a treatment with halogens or sulfuryl chloride (93MI1). Compounds 34 were obtained in almost quantitative yields. 

Halides, reduction of organic, with magnesium and 2 propanol, 47,106 Halogenation of anisole to a chloroani sole with sulfuryl chloride, 47,... 

Sufficient activation was present in 5-ethylamino-2-oxoimidazolo [4,5-6]pyrazine (173) for it to be halogenated in the 6-position by chlorine and bromine in acetic acid or by sulfuryl chloride (69FRP1578366 71BRP1248146). The 2-oxo group could be replaced by chlorine (75KFZ10 76KFZ35). 

Besides radical additions to unsaturated C—C bonds (Section III.B.l) and sulfene reactions (see above), sulfonyl halides are able to furnish sulfones by nucleophilic substitution of halide by appropriate C-nucleophiles. Undesired radical reactions are suppressed by avoiding heat, irradiation, radical initiators, transition-element ion catalysis, and unsuitable halogens. However, a second type of undesired reaction can occur by transfer of halogen instead of sulfonyl groups283-286 (which becomes the main reaction, e.g. with sulfuryl chloride). Normally, both types of undesired side-reaction can be avoided by utilizing sulfonyl fluorides. 

The most common preparative procedures involve use of the halogen, usually bromine, in acetic acid. Other suitable halogenating agents include IV-bromosuccinimide, tetrabromocyclohexadienone, and sulfuryl chloride. 

As underlined above, formation of these compounds by halogenation of dialkyl esters of 1,2-alkadienephosphonic acids is the major direction of the reaction. Even in the case of dialkyl esters of propadienephosphonic acid, some 1,2-oxaphosphole derivatives could be detected [86], On using sulfuryl chloride as electrophilic reagent, only 3,3-disubstituted- and 3-monosubstituted substrates could be transformed in oxaphosphole derivatives [39], Thus, the main role of the substituent at the C3 atom of the allenephosphonate system, for the formation of 2,5-dihydro-l,2-oxa-phosphole-2-oxide derivatives, was demonstrated. 

The selective replacement of hydroxyl groups in carbohydrates by halogen has mainly been achieved by the use of (a) sulfuryl chloride, (b) reagents based on phosphorus compounds, and (c) reagents of the... 

Erickson extended these reactions to useful preparations of both 3-chloroindole and several 2,3-dihaloindoles, many of which occur naturally [5], When the C-3 position is already substituted, halogenation usually occurs at C-2. A summary of these halogenations is shown below. Erickson was able to improve Piers synthesis of 2 to a yield of 82%. Interestingly, the action of sulfuryl chloride on 3-iodoindole gives the ipso product 3-chloroindole in 84% yield. 

The use of sulfuryl chloride for free radical chlorination of aliphatic carboxylic acids gives mixtures of positional isomers.7 However, with the cyclobutane ring, the attack is much more selective. The present method provides a procedure for free radical halogenation of a cyclobutane ring. 

Halogenation Reactions. Chlorination of 4-acyl-2-phenyl-5(4f/)-oxazolones 213 with sulfuryl chloride leads to the corresponding 4-chloro derivatives 214 (Scheme 7.66). These compounds are useful intermediates in organic synthesis. In particular, hydrolytic cleavage of 214 affords a-chloro-a-acylamino ketones... 

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