Reactions with DMSO

DMF, in alkylation of aminothiazoles, 35 in ambident reactivity, 36 in cyclizations, 50 DMSO, reaction with CS2,61 Dopamine content in brain, 146 Dopamine hydroxylase inhibitor, 152 Double bond, addition to, 40 ozonolysis of, 71... 

The synthesis of allenes of the type RpCH C CHa is an easier task, now made even easier by a new method based on the reaction of perfluoroalkyl coppers with propargyl halides or alcohols. The alkyl copper is generated in situ from copper bronze and a perfluoroalkyl iodide in DMSO reaction with propargyl bromide is extremely rapid and a minor explosion occurred during work-up. 

Reaction of CO with 7 in DMSO/H2O gave reversibly [Ir(CO)3(TPPTS)2]Cl 216 in H2O and DMSO and Ir(CO)2Cl(TPPTS)2 217 in DMSO only. In H2O, further reactions occur slowly, including WGS reaction and formation of [Ir(CO)2(TPPTS)3] 218. In DMSO, reaction with CO readily forms [Ir(CO)3(TPPTS)2] 219 no reaction with CO is observed in H2O. Reaction of 218 with H2 occurs through TPPTS dissociation giving [Ir(CO)2(H)2(TPPTS)2] 220 initially before reaction with free TPPTS gives [Ir(CO)(H)2(TPPTS)3] 221 as the final product. ... 

TT-Aliylpalladium chloride reacts with a soft carbon nucleophile such as mal-onate and acetoacetate in DMSO as a coordinating solvent, and facile carbon-carbon bond formation takes place[l2,265], This reaction constitutes the basis of both stoichiometric and catalytic 7r-allylpalladium chemistry. Depending on the way in which 7r-allylpalladium complexes are prepared, the reaction becomes stoichiometric or catalytic. Preparation of the 7r-allylpalladium complexes 298 by the oxidative addition of Pd(0) to various allylic compounds (esters, carbonates etc.), and their reactions with nucleophiles, are catalytic, because Pd(0) is regenerated after the reaction with the nucleophile, and reacts again with allylic compounds. These catalytic reactions are treated in Chapter 4, Section 2. On the other hand, the preparation of the 7r-allyl complexes 299 from alkenes requires Pd(II) salts. The subsequent reaction with the nucleophile forms Pd(0). The whole process consumes Pd(ll), and ends as a stoichiometric process, because the in situ reoxidation of Pd(0) is hardly attainable. These stoichiometric reactions are treated in this section. 

For coupling, the cheaper aryl fluorosulfonate 713 is used as an alternative to the expensive aryl triflates to give the same results[473]. The arenesulfonates 714 are active for the reaction with vinylstannanes when dppp and LiCI are used in DMSO[583], The bromide 715 attacks the arylstannane moiety selectively without reacting with the organoboron moiety in 716 in the absence of a base[584]. 

Through reaction with sulfide or elemental sulfur at 215°C, lignosulfonates can also be used in the commercial production of dimethyl sulfide and methyl mercaptan (77). Dimethyl sulfide produced in the reaction is further oxidized to dimethyl sulfoxide (DMSO), a useful industrial solvent (see Sulfoxides). 

Nucleophilic Substitution Route. Commercial synthesis of poly(arylethersulfone)s is accompHshed almost exclusively via the nucleophilic substitution polycondensation route. This synthesis route, discovered at Union Carbide in the early 1960s (3,4), involves reaction of the bisphenol of choice with 4,4 -dichlorodiphenylsulfone in a dipolar aprotic solvent in the presence of an alkaUbase. Examples of dipolar aprotic solvents include A/-methyl-2-pyrrohdinone (NMP), dimethyl acetamide (DMAc), sulfolane, and dimethyl sulfoxide (DMSO). Examples of suitable bases are sodium hydroxide, potassium hydroxide, and potassium carbonate. In the case of polysulfone (PSE) synthesis, the reaction is a two-step process in which the dialkah metal salt of bisphenol A (1) is first formed in situ from bisphenol A [80-05-7] by reaction with the base (eg, two molar equivalents of NaOH),... 

Vinyl chloride reacts with sulfides, thiols, alcohols, and oximes in basic media. Reaction with hydrated sodium sulfide [1313-82-2] in a mixture of dimethyl sulfoxide [67-68-5] (DMSO) and potassium hydroxide [1310-58-3], KOH, yields divinyl sulfide [627-51-0] and sulfur-containing heterocycles (27). Various vinyl sulfides can be obtained by reacting vinyl chloride with thiols in the presence of base (28). Vinyl ethers are produced in similar fashion, from the reaction of vinyl chloride with alcohols in the presence of a strong base (29,30). A variety of pyrroles and indoles have also been prepared by reacting vinyl chloride with different ketoximes or oximes in a mixture of DMSO and KOH (31). 

Halogeno-l-methyl-l,2,3-triazoles undergo substitution reactions with amines, but the 4-halogeno analogs do not. 5-Chloro-l,4-diphenyl-l,2,3-triazole with sodium cyanide in DMSO gives the cyano derivative (63JCS2032). 1-Substituted 3-chloro- and 5-chloro-l,2,4-triazoles both react with amines. 

Sheads studied the reactivity of over 100 alcohols with 2,1-benzisoxazoles with 70% aqueous perchloric acid in nitromethane 74DIS(B)147). The rates of quaternization by reaction with Mel in DMSO were also studied and the dynamics of the reaction investigated <74AJC122l). 

Thermal conversion of diazirines to linear diazo compounds was postulated occasionally and proved by indirect methods. The existence of a diazo compound isomeric to diazirine (197) was proved spectroscopically on short thermolysis in DMSO (76JA6416). An intermediate diazoalkane was trapped by reaction with acetic acid, yielding the ester (198) (77JCS(P2)1214). 

DMSO, NaCN, 125-180°, 5-48 h, 65-90% yield.This cleavage reaction is successful for aromatic systems containing ketones, amides, and carboxylic acids mixtures are obtained from nitro-substituted aromatic compounds there is no reaction with 5-methoxyindole (180°, 48 h). 

This reaction can also be applied to tertiary nitroalkanes lacking any additional functional group. The reactions with nitro compounds lacking additional anion-stabilizing groups are carried out in DMSO solution ... 

Several other reaction types have also appeared in the literature but are sometimes purely formal schemes dating from the time when the solvent was (incorrectly) thought to undergo self-ionic dissociation into SO + and S03 or SO " and S205 . More recently it has been shown that, whereas neither SO2 nor OSMe2 (dmso) react with first-row transition metals, the mixed solvent smoothly effects... 

The ionic species 5, as well as 6, represent the so-called activated dimethyl sulfoxide. Variants using reagents other than oxalyl chloride for the activation of DMSO are known. In the reaction with an alcohol 1, species 5, as well as 6, leads to the formation of a sulfonium salt 7 ... 

Treatment of dimethylsulfoxide (DMSO) with sodium hydride generates methylsulfinyl carbanion (dimsyl ion), which acts as an efficient base in the production of ylides. The Wittig reaction appears to proceed more readily in the DMSO solvent, and yields are generally improved over the reaction with -butyl lithium (i). Examples of this modification are given. 

Differentiation between inner- and outer-sphere complexes may be possible on the basis of determination of activation volumes of dediazoniations catalyzed by various metal complexes, similar to the differentiation between heterolytic and homolytic dediazoniations in DMSO made by Kuokkanen, 1989 (see Sec. 8.7). If outer-sphere complexes are involved in a dediazoniation, larger (positive) volumes of activation are expected than those for the comparable reactions with inner-sphere complexes. Such investigations have not been made, however, so far as we are aware. 

Corey and Chaykovsky had discovered that dimethyl sulfoxide is converted to methyl-sulfinyl carbanion upon treatment with sodium hydride114 and that this conjugate base of DMSO reacts with various electrophiles115. This finding has opened up various reactions with a-sulfmyl carbanions derived from sulfoxides, since the sulfinyl function can be removed either by thermolysis or by subjecting the compound to reductive desulfurization. Thus a-sulfmyl carbanions have become versatile synthetically useful reagents. 

The decay of the absorption of e, - was followed at 1000 nm30 or 900 nm50 where the oxidizing species do not absorb. It was found30 that esol decays by first-order kinetics. A second-order rate constant was calculated assumi ng that the decay is only by reaction with DMSO. These second-order rate constants appear to go through a maximum between 0.20 and 0.43 mole fraction of DMSO where k = 5.6 x 106 m 1 s , however, there is not a large difference between the different concentrations as the lowest value is 2.9 x 10 ... 

This mechanism is further proved by the observation that addition of 0.05 m Br to aqueous DMSO results in reduced intensity of the ethane signal. Bromide ion at this concentration does not effectively compete with DMSO for OH (kom-DMso = 7 x 109 m 1s 1, [DMSO] = 0.23m, k0H + Br = 1-1 x 1010m-1s-1) and the effect of Br can be due to its reaction with the cation of DMSO30 34 found also in pure DMSO, (CH3)2SO + is reduced by Br- and consequently cannot react with the spur electrons. 

The anion of DMSO undergoes a phenylation reaction with aryl halides under sunlight stimulation38. The presence of benzhydryl methyl sulfoxide (maximum yield 5%) in all runs, the sunlight activation, the order of reactivity of halobenzenes (I > Br > Cl), the inhibition of the reaction with oxygen, all hint at the SRN139-44 mechanism (Scheme 3). 

Ce4+ is a versatile one-electron oxidizing agent (E° = - 1.71 eV in HC10466 capable of oxidizing sulfoxides. Rao and coworkers66 have described the oxidation of dimethyl sulfoxide to dimethyl sulfone by Ce4+ cation in perchloric acid and proposed a SET mechanism. In the first step DMSO rapidly replaces a molecule of water in the coordination sphere of the metal (Ce v has a coordination number of 8). An intramolecular electron transfer leads to the production of a cation which is subsequently converted into sulfone by reaction with water. The formation of radicals was confirmed by polymerization of acrylonitrile added to the medium. We have written a plausible mechanism for the process (Scheme 8), but there is no compelling experimental data concerning the inner versus outer sphere character of the reaction between HzO and the radical cation of DMSO. 

As previously discussed, solvents that dissolve cellulose by derivatization may be employed for further functionahzation, e.g., esterification. Thus, cellulose has been dissolved in paraformaldehyde/DMSO and esterified, e.g., by acetic, butyric, and phthalic anhydride, as well as by unsaturated methacrylic and maleic anhydride, in the presence of pyridine, or an acetate catalyst. DS values from 0.2 to 2.0 were obtained, being higher, 2.5 for cellulose acetate. H and NMR spectroscopy have indicated that the hydroxyl group of the methy-lol chains are preferably esterified with the anhydrides. Treatment of celliflose with this solvent system, at 90 °C, with methylene diacetate or ethylene diacetate, in the presence of potassium acetate, led to cellulose acetate with a DS of 1.5. Interestingly, the reaction with acetyl chloride or activated acid is less convenient DMAc or DMF can be substituted for DMSO [215-219]. In another set of experiments, polymer with high o -celliflose content was esterified with trimethylacetic anhydride, 1,2,4-benzenetricarboylic anhydride, trimellitic anhydride, phthalic anhydride, and a pyridine catalyst. The esters were isolated after 8h of reaction at 80-100°C, or Ih at room temperature (trimellitic anhydride). These are versatile compounds with interesting elastomeric and thermoplastic properties, and can be cast as films and membranes [220]. 

A direct method for preparing a carboxylic acid treats an alkyl halide with NaN02 in acetic acid and DMSO. Reaction of an alkyl halide with ClCOCOaMe and (Bu3Sn)2 under photochemical conditions leads to the corresponding methyl... 

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