Alkylthio, alkylsulfinyl and alkylsulfonyl groups

The SR substituent can be displaced nucleophilically by amines and hydroxide (867 — 868) and removed reductively by dissolving metals, e.g. from (869) with Zn/H+. Oxidation gives the corresponding sulfoxide and sulfone, in which nucleophilic displacement is easier. Thus, 2- and 4-(phenylsulfonyl)pyrimidines give the corresponding replacement products with various nitrogen and 

Oxidation of alkylthio- (or arylthio-)l,2-diazines to the corresponding sulfmyl and sulfonyl derivatives has been described in CHEC(1984) and GHEC-II(1996) 1984CHEC(2)1, 1996CHEC-II(6)1 . 

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Alkylthio groups can be oxidized to alkylsulfinyl and alkylsulfonyl groups <85TL2419, 88YZ142, 89JOC1249, 89JOC4984>... 

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... 

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