Oxidative phenylsulfonyl groups

Lithiated indoles can be alkylated with primary or allylic halides and they react with aldehydes and ketones by addition to give hydroxyalkyl derivatives. Table 10.1 gives some examples of such reactions. Entry 13 is an example of a reaction with ethylene oxide which introduces a 2-(2-hydroxyethyl) substituent. Entries 14 and 15 illustrate cases of addition to aromatic ketones in which dehydration occurs during the course of the reaction. It is likely that this process occurs through intramolecular transfer of the phenylsulfonyl group. 

An active-site model has been proposed to explain the high asymmetric oxidation of sulfide to sulfoxides75 (Fig. 6). The model consists of three pockets, A, B, and C, where pocket B, defined by the two chlorine atoms and the phenylsulfonyl group, is responsible for the high enantioselectivity exhibited for the oxidation of sulfides Rl-S-Rs. The absolute stereochemistry of the final sulfoxides is predicted in terms of a simple steric model, which involves minimization of nonbonded interaction between the RL and Rs groups of the sulfides (RL-S-Rs) and the active site surface of the oxaziridine in an orientative planar transition state. 

Amination of 2-fluoropyrazine 1-oxide with a variety of amines proceeds smoothly at 40-50°C to form excellent yields of the aminopyrazine A-oxides within 2 h <84H(22)il05>. This reactivity is in contrast to that in the amination of 2-chloropyrazine 1-oxide, where higher temperatures (100-110°C) are needed. An electron-withdrawing cyano substituent adjacent to a phenylsulfonyl group prompts its nucleophilic replacement by amines <92JHC1689>, for example, reaction of 3-phenyl-sulfonylpyrazinecarbonitrile (60) with ethylamine in the presence of triethylamine at room temperature for 2 hours produces 3-(A-ethylamino)pyrazinecarbonitrile (61) in 78% yield (Equation... 

Reaction of 3,4-bis(phenylsulfonyl)-l,2,5-oxadiazole oxide isomers with ethanol and ethanethiol in basic medium gave the expected alkoxy- and alkylthio-substituted (benzenesulfonyl)furoxans, respectively <1996JHC327, 1997FES405>. Nucleophilic substitution of the sulfonyl group of 3,4-bis-(benzenesulfonyl)furoxan 222 in the presence of aqueous NaOH in tetrahydrofuran (THF) furnished the corresponding 3 -0-(3-benzenesulfonylfur-oxan-4-yl) derivative 223 in 79-92% yield (Equation 44) <2004JME1840>. 

The well-known method of furazan formation is based on nitrosation of alkenes. Thus, several NO donor 3,4-disubstituted 1,2,5-oxadiazole 2-oxide derivatives and the related 1,2,5-oxadiazoles, containing methylsulfonylphe-nyl, phenylsulfonyl, sulfonylamidophenyl, and phenylsulfonylamido groups were synthesized by nitration of... 

The invention of the triflate (trifluoromethylsulfonyl) group — one of the world s best leaving groups — has led to its use in palladium chemistry [42]. Conway and Gribble described the synthesis of 3-indolyl triflate 34 [12] and 2-indolyl triflate 35 from oxindole [43]. Mdrour synthesized the N-phenylsulfonyl derivative 36 by employing a Baeyer-Villiger oxidation of the appropriate indolecarboxaldehyde [44],... 

Methylation of free hydroxyl groups by means of Purdie s reagents usually proceeds smoothly,176 without occurrence of desulfonylation.220 Thus, by treatment20 of methyl 2,3-di-0-methyl-4-0-phenylsulfonyl-/8-D-glucoside with silver oxide plus boiling methyl iodide under reflux, the 2,3,6-trimethyl ether was obtained. However, although methyl... 

Examples of selective side-chain oxidation were reported for two reagents Ceric ammonium nitrate was found to convert 5-methylpyrrole-2-carboxylates to 5-formylpyrrole-2-carboxylates. <95TL4345> Several examples of oxidation of C2 and C3 methyl groups to formyl in 1-(phenylsulfonyl)indoles with Mn02 were reported. <95SC2407>... 

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