Benzenesulfenic acid

Treatment of a-dichloromethyl phenyl sulfoxide with lithium diisopropylamide in THF gave monolithiated derivative 122, which upon further treatment with aldehyde afforded the )S-hydroxy-a-dichlorosulfoxide 123. Thermolysis of 123 gave dichloroketone 124, by extruding benzenesulfenic acid as shown below . Similarly, in the reaction of lithio-a-fluoromethyl phenyl sulfoxide and aldehyde, fluoromethyl ketone 126 was obtained, after thermolysis of the hydroxy intermediate 125. Diethylphosphorylmethyl methyl sulfoxide was shown by Miko/ajczyk and coworkers to be lithiated with n-BuLi to intermediate 127, which upon treatment with carbonyl compounds afforded the corresponding a, -unsaturated sulfoxides 128 in good yields. 

Phenyl vinyl sulfoxide can serve as an acetylene equivalent. Its D-A adducts can undergo thermal elimination of benzenesulfenic acid. 

Table 10. Synthesis of Alka-2,4-dienoic Acids 28 by Claisen Rearrangement and Benzenesulfenic Acid Elimination12...

Dinitrobenzenesulfenyl chloride is an explosion hazard both in its preparation and its use. Because of its explosive nature, temperatures above 90°-100cC should be avoided in its preparation. Care should be exercised in its storage. The reagent may be destroyed by addition to several volumes of 20% NaOH and washing away with water (Refs 47 67). See also under Benzenesulfenic Acid and Derivatives, Vol 2,... 

B60-R to B61-R, under Benzenesulfenic Acid and Derivatives . An addnl derivative is presented below ... 

Di-r-butylbenzenes.1 This reagent undergoes a Diels-Alder reaction with phenyl vinyl sulfoxide, an acetylene equivalent (8,399), with loss of benzenesulfenic acid to give o-di-f-butylbenzene in 77% yield. 

Phenol annelation.1 Methyl vinyl ketone (and substituted vinyl ketones) undergo Robinson annelation with the j8-keto sulfoxide (1) to afford the 5,6,7,8-tetrahydro-2-naphthol (2) with loss of benzenesulfenic acid. Sodium methoxide is used as base, and the reaction proceeds at 0 -> 25°. 

In the following examples, sulfur dioxide and benzenesulfenic acid (benzene-sufinic acid) are simultaneously extruded from the initial adducts. In this way, a series of highly congested benzene derivatives, which are otherwise difficult to prepare, were synthesized in good overall yields (Scheme 33) [39,40,159,160]. 

Protection of a-methylene-y-butyrolactones. Sodium thiophenoxide undergoes Michael addition to a-methylene-7-butyrolactones in nearly quantitative yield. Deblocking involves oxidation of the sulfide to the sulfoxide and thermal elimination of benzenesulfenic acid. The yield in all steps is high. ... 

Suhstituted resorcinols. A typical synthesis involves the base-catalyzed conjugate addition of 1 to 2 followed by cyclization to form 3 as a mixture of isomers. This product loses benzenesulfenic acid when heated to give 5-phenyl-resorcinol (4). 

DienonesJ A new synthesis of 2,4-dienones (4) involves reaction of an allylic alcohol (1) with an allenyl phenyl sulfoxide (2) in benzene (ice bath). The resulting enol ether (3) is treated with this base, which induces Claisen rearrangement and elimination of benzenesulfenic acid, with formation of the dienone 4 (equation I). 

Simply heating the 2-deoxy-sulfoxide 1 in benzene caused elimination of benzenesulfenic acid, producing the corresponding glycal in 98 % yield. ... 

For example, treatment with p-toluenesulfonic acid in methanol affords dimethoxyacetals which can be further hydrolyzed to aldehydes (eq 2). Aldehydes are also available in one step by oxidation of the sulfide to the sulfoxide with m-chloroperbenzoic acid and hydrolytic workup (eq 2). Vinyl ethers are produced via a thermal elimination of benzenesulfenic acid (eq 3). Alternately, the anion formed from the addition of methoxy(phenylthio)methyllithium to aldehydes can be treated with carbon disulfide and iodomethane to form a xanthate which when treated with tributylstannane effects a radical reductive elimination to form (Z)- and ( )-enol ethers (eq 4). ... 

VSO can be used to form block copolymers with PS followed by VSO elimination to form EA-PS block copolymers [73,89,90]. th monomers can be polymerized anionical the s ene was initiated first and end-capped with 1,1-diphenyl ethylene (DPE). Vfith the addition of a few drops of DPE to the living styr solution, the styryl carbanions were converted to diphenyl methyl car-banions [91], which were bull, less reactive, and less nucleophilic than the styryl carbanions, thus minimizing any side reactions. The VSO monomer was then added to the DPE-capped styryl chains to generate a PS/PVSO copolymer. The resulting precursor copolymer had PDIs that were as low as 1.09. To thermally eliminate the benzenesulfenic acid moieties from the PVSO block, the copolymer was heated from room temperature to 80° C at l°C/min and then held at 80°C for 1 h [90]. It was then heated to 150°C at I°C/min to get the maximum amoimt of elimination (87-92%). Whereas the PS/PVSO precursor copolymer was soluble in many solvents, the PS/PA copolymer was soluble only when the PA content was less than 50 mol%. th 78 mol% PA content the conductivity of the copolymer was 8 x 10 S/cm after iodine doping. 

The crystallographic analysis of 13 indicated that the calixarene macrocycle of 13 adopts the 1,2,3-altemate conformation and surrounds the benzenesulfenic acid... 

Acetylene is not only dangerous to handle at high temperatures and pressures, but is a poor dienophile. A potentially useful acetylene equivalent is phenyl vinyl sulfoxide. Its merits are that it is a reasonably good dienophile and that its Diels-Alder adducts eliminate benzenesulfenic acid readily, often under the conditions of their formation. 

Phenyl vinyl sulfoxide is a useful acetylene equivalent. Its Diels-Alder adducts can undergo elimination of benzenesulfenic acid. 

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