Formaldehyde dimethyl dithioacetal

Ogura [296, 297] has proposed other interesting uses of MMTS (also known as FAMSO, for formaldehyde dimethyl dithioacetal S-oxide) and also of the two following dithioacetal monosulfones ... 

KETONES N.O-Dimethylhydroxylamine hydrochloride. N,N,-Diphenyl-/>-mcthoxyphenylchloromethyleniminum chloride. Formaldehyde dimethyl dithioacetal S.S-dioxidc 4-Fonmyl l methylpyridiniuni bcnzencsullonatc. l.ithi[Pg.651]

METHYL CARBOXYLATES Formaldehyde dimethyl dithioacetal S,S-dioxide. 

Formaldehyde dimethyl dithioacetal 5-oxide (FAMSO 113) and its ethyl analog are widely used as synthetic carbonyl equivalents. - Addition of the lithio derivative of (113) to aldehydes and ketones followed by acidic hydrolysis is a preparative method for a-hydroxy aldehyde derivatives (equation 27). A chiral analog of (113), (5)-formaldehyde di-p-tolyl dithioacetal 5-oxide (114), can be synthesized from (-)-mentyl (/ )-p-toluenesulfinate. °° The reaction of the lithio derivative of (5)-(114)... 

FAMSO formaldehyde dimethyl dithioacetal S-oxide (=MMTS)... 

An alternative approach to benzo[Z ]thiophene derivatives includes treatment of an aryl-substituted ketene dithioacetal monoxide 188 with trifluoromethanesulfonic anhydride [99] (TfjO) in the presence of K2CO3 in toluene at 25 °C, followed by addition of ethanolamine to the reaction mixture, provided benzo[fc]thiophenes, including 3-trifluoromethylbenzo[Z ]thiophene 189, in good yields. The cyclization proceeded through formation of reactive sulfonium electrophile [1(X)]. The synthesis of the starting material 188 was also facile and scalable, starting from aryl ketone 186 and formaldehyde dimethyl dithioacetal S-oxide (FAMSO) [101]. 

A range of keto-esters have been reduced to hydroxy-esters (in 42—84% yield) with lithium aluminium hydride and silica gel. Formaldehyde dimethyl dithioacetal 55-dioxide (98) is converted into the a-alkoxy-ester (99) by the sequence shown in Scheme 55 yields for each of the three stages are between 52 and 88%.i 2... 

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