2- Alkylsulfinyl

In a series of papers, Barlin and Brown117-181 reported their investigations of the nucleophilic displacement reactions of 2-alkylthio-, 2-alkylsulfinyl-, and 2-alkylsulfonyl-quinoxalines. 2-Methylsulfonyl-quinoxaline reacts about 60 times more rapidly with methoxide ion than 2-chloroquinoxaline, owing to a lower activation energy of reaction.177 2-Methylsulfinylquinoxaline (171) is about as reactive as the methylsul-fonyl compound, but 2-methylthioquinoxaline (172) is less reactive than the chloroquinoxaline. 79 In compounds (2-SO R) related to 169, 171, and 172, the ease of nucleophilic displacement by methoxide ion markedly decreases as the size of the alkyl group R increases Me > Et > isoPr > ter/-Bu.181... 

Alkylthio)- and 2-(alkylsulfinyl)-l-alkenyl ketones (16a) and (16b) reacted with a variety of amines to give 2-amino-1-alkenyl ketones (17a) and (17b) (Scheme 10). 

When 2-alkylsulfinyl-, 2-arylsulfinyl-, and 1,2-aralkylsulfinyl-benzimidazoles react with thiols, the unsymmetrical disulfides are obtained (instead of the symmetrical ones), together with ipso-substitution products. The reaction is believed to be initiated by protonation of the benzimidazole nitrogen. The sulfenic acid is then eliminated after the ipso-substitution by thiolate. The sulfonic acid, once formed, is so unstable that it reacts immediately with thiol or dimerizes to form thio-sulfinates from which the unsymmetrical disulfides are derived (Equation (56)) <87JOC4620>. 

Since 2-alkylsulfinyl [1,3,5] triazines 194 can be substituted easily in various ways, this approach constitutes a novel and efficient synthesis of 2,6-disubstituted triazines 195 <1998TL5725>. 

Recently, Fuji and coworkers have reported the enantioselective construction of a highly functionalized bicyclo[4.3.0] system through the Diels-Alder cycloaddition between Danishefsky s diene and an enantiomerically pure a,p-unsaturated sulfoxide substituted at the p-position by an electron-withdrawing nitro group [181,182]. Despite the numerous examples of diastereoselective Diels-Alder cycloadditions described above for enantiomerically pure P-substituted-a,P-unsaturated sulfoxide dienophiles, this is the first report of an enantioselective version of the reaction, where the chiral auxiliary is eliminated under the reaction conditions or during the workup procedure. Thus, the Diels-Alder reaction between optically active 2-alkylsulfinyl-l-nitroalkene (228) and Danishefsky s diene afforded endo and exo cycloadducts (229) and (230) in good yields with high enantiomeric excesses (Scheme 5.73). 

Pyrimidine, I-alkyl-2-methyltetrahydro-C-thioacylation, 4, 807 Pyrimidine, 4-alkylsulfinyl-nucleophilie displaeement reaetions, 3, 97 Pyrimidine, 6-alkylsulfinyl-nucleophilic displacement reactions, 3, 97 Pyrimidine, 2-alkylsulfonyl-nueleophilie displaeement reactions, 3, 97 Pyrimidine, 4-alkylsulfonyl-nucleophilic displacement reactions, 3, 97 Pyrimidine, 6-alkylsulfonyl-nucleophilie displaeement reactions, 3, 97 Pyrimidine, alkylthio-dealkylation, 3, 95 desulfurization, 3, 95 oxidation, 3, 96 synthesis, 3, 135, 136 Pyrimidine, 2-alkylthio-aminolysis, 3, 96 hydrolysis, 3, 95 Prineipal Synthesis, 3, 136 Pyrimidine, 4-alkylthio-aminolysis, 3, 96 hydrolysis, 3, 95 Pyrimidine, 6-alkylthio-aminolysis, 3, 96 hydrolysis, 3, 95 Pyrimidine, 4-allenyloxy-rearrangement, 3, 93 Pyrimidine, 4-allyloxy-2-phenyl-rearrangement, 3, 93 Pyrimidine, 4-allynyloxy-rearrangement, 3, 93 Pyrimidine, 4-anilino-2,5,6-trifluoro-NMR, 3, 63 Pyrimidine, 2-aryl-pyrroleaeetic aeid from, 4, 152 Pyrimidine, arylazo-synthesis, 3, 131 Pyrimidine, 4-arylazo-reduetion, 3, 88... 

These constitute the only category of substituted alkylsulfinyl and alkylsulfonyl groups for which there appears to be appreciable information. Compounds containing these groups have often been used in spectroscopic studies of inductive and resonance effects... 

Reactions. Although both C-alkylsulfinyl- and C-alkylsulfonylquinoxalines have great potential as versatile intermediates, especially for displacement reactions, they have seldom been used as such in recent years for example, their hydrolysis, alcoholysis, and phenolysis have been totally ignored. However, an example of the conversion of an arylsulfonyl-into a halogenoquinoxaline has been given in Section 3.1.5, and some other reported reactions are illustrated in the following examples. 

By aminolysis of alkylsulfinyl- or alkylsulfonylquinoxalines (nuclear, primary, secondary, or tertiary) Section 5.4. 

In 1995 Vanderzande et al. [89] published a novel, modified Gilch procedure to unsubstituted PPV 60 starting from l-chloromethyl-4-(alkylsulfinyl)methyl-benzenes (68). The initial step, elimination of HCl with NaH as a strong base in NMP or DMF, leads to the formation of the sulfinyl-substituted 1,4-xylylene... 

Heesing and coworkers have reported the rearrangement of 0-alkylsulfinyl-iV-benzoyl-iV-phenylhydroxylamine (143) at — 70°C to the corresponding sulfonamide together with the o- and p-alkylsulfonyl derivatives 144 and 145 (equation 89). The reaction has been suggested to proceed by an intramolecular radical pair mechanism, as evidenced by experiments with oxygen-18 labeling and C-CIDNP effects. 

Simple dienes are not reactive enough toward chiral l-(alkylsulfinyl)-2-nitroalkenes. To resolve this problem, the reaction of optically active l-(alkylsulfinyl)-2-nitroalkenes with simple... 

Aversa and colleagues168 studied the facial selectivities in the reactions of (5s)- and (Z s)-3-alkylsulfinyl-l-methoxy-l,3-butadienes with several dienophiles. Table 11 summarizes the results of the completely endo selective reaction of 258 with /V-phenylmaleimide (165) and the effects of different catalysts on the diastereofacial selectivity of this reaction (equation 71)168e. In the case of the uncatalyzed reaction, the dienophile attacked the... 

The sulfur derivatives of methylcarbamate insecticides which have been described are those containing a sulfenyl (or thio) sulfur attached to the methylcarbamate nitrogen atom. N-Alkylsulfinyl or N-aryIsulfinyl derivatives (general structure... 

Recently, Koizumi et al. reported that the use of high pressures allows exclusion of Lewis acids (which are not compatible with many dienes and/or adducts) in the cycloadditions of acrylates [43]. Thus, methyl 3-alkylsulfinyl acrylate 29 is able to react with cyclopentadiene, furan, and 2-methoxyfuran at 12.6 Kbar (Scheme 14). Both 7r-facial and endo/exo selectivities are very high in reactions with cyclopentadiene (only one adduct was obtained), whereas with furan derivatives the endo/exo selectivity is clearly lower. In reactions with cyclopentadiene it could be established that high pressures do not have a significant influence on the diastereoselectivity. The transformation into (-)-COTC of the major adduct obtained from 2-methoxyfuran was carried out in order to confirm its absolute configuration. 

Among the substances which are described here, the polymers have only a vehicle function or they represent the deposit form. Besides the above-described polymeric N-oxides and plasma substitutes further water-soluble nontoxic polymers, such as polymers from 2-hydroxyethyl acrylate or methacrylate (71), alkylsulfinyl acrylates and methacrylates (72), diethoxyethylenes (73), and other substances as yet pharmacologically tested, are in question. Differentiation, however, can be between preparations, whose active substance has to be split off - a fact which has to be taken for granted in the case of substances that are active in the central nervous system -and substances that are still active at the polymeric carrier. Only recently it has been shown by Kaplan (74, 75) that this is possible, at least in such cases where an activity is to be supposed via receptors in the cell membrane. In many other cases this question cannot be cleared up unequivocally. 

Chiral (Z)-l-(alkylsulfinyl)-2-nitroalkenes underwent Lewis acid-promoted Diels-Alder reactions, with complete control of the diastereoselectivity as well as endo selectivity, to yield single cycloadducts.114 Enantiopure (-)-trans-benzo[d ]dithi-ine-S.S -dioxide underwent Diels-Alder cycloadditions with a series of cyclic dienes, affording adducts with diastereoselectivities ranging from fair to high.113... 

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