3- -3,4-dihydro- -1,1-dioxid

Reactions. Heating an aqueous solution of malonic acid above 70°C results in its decomposition to acetic acid and carbon dioxide. Malonic acid is a useful tool for synthesizing a-unsaturated carboxyUc acids because of its abiUty to undergo decarboxylation and condensation with aldehydes or ketones at the methylene group. Cinnamic acids are formed from the reaction of malonic acid and benzaldehyde derivatives (1). If aUphatic aldehydes are used acryhc acids result (2). Similarly this facile decarboxylation combined with the condensation with an activated double bond yields a-substituted acetic acid derivatives. For example, 4-thiazohdine acetic acids (2) are readily prepared from 2,5-dihydro-l,3-thiazoles (3). A further feature of malonic acid is that it does not form an anhydride when heated with phosphorous pentoxide [1314-56-3] but rather carbon suboxide [504-64-3] [0=C=C=0], a toxic gas that reacts with water to reform malonic acid. 

Nitrofurathiazide. 6-Acetylamino-3,-4-dihydro-3-(5-nitro-2-furanyl)-2JT-l,2,4-benzothiadiazine 1,1-dioxide, nitrofurathiazide, is synthesized from 4-acetylanaino-2-aniinobenzenesulfonaniide with 5-nitro-2-furancarboxaldehyde (45). The product has been employed as an antibacterial agent for humans and, in combination with other dmgs, has been used for acute or chronic otitis externa of dogs and cats. 

Saccharin. Saccharin [81-07-2] 3-oxo-2,3-dihydro-l,2-ben2isothia2ole 1,1-dioxide (i9-sulfoben2imide or (9-ben2osulfimide), (5) was accidentally discovered to be a sweet compound in 1878. A pilot plant was set up in New York to manufacture saccharin, which was displayed in a London exposition in 1885 (70). Since that time, saccharin has been used in many parts of the world. 

Borohydride reduction of 3-aryl-l,2-benzisothiazole 1,1-dioxides gives the 2,3-dihydro compounds 73JMC1170). Reduction of either 2-methylsaccharin or 2-hydroxymethylsac-charin with lithium aluminum hydride gives the same product, iV-methyl-o-hydroxymethyl-benzenesulfonamide (73AHC(15)233). 

When saccharin is treated with diethyl phosphorothiolothionate, the 3-ethylmercapto compound is obtained, rather than the expected organophosphorus compound (77 ACS(B)460). Treatment of saccharin with phosphorus pentoxide and amines gives 3-(substituted-amino)-1,2-benzisothiazole 1,1-dioxides, via an intermediate phosphate (81ZN(B)1640). Reduction of saccharin with zinc and hydrochloric acid gives 2,3-dihydro-l,2-benzisothiazole 1,1-dioxide, the method being used to estimate saccharin in foodstuffs (75MI41701). 

Isothiazole, 3,5-dichloro-4-cyano-synthesis, 6, 166 Isothiazole, dihydro-1,1-dioxide... 

Pyrazine, 2,5-dichloro-3,6-difluoro-synthesis, 3, 190-191 Pyrazine, dihydro-, 3, 177 Pyrazine, 1,2-dihydro-oxidation, 3, 178 reduction, 3, 177 Pyrazine, 1,4-dihydro-antiaromaticity, 3, 177-178 synthesis, 3, 177 Pyrazine, 2,3-dihydro-oxidation, 3, 178 Pyrazine, 2,5-dihydro-synthesis, 3, 178 Pyrazine, 3,6-dihydro-synthesis, 3, 184 Pyrazine, 2,5-dihydroxy-oxidation, 3, 175 Pyrazine, 2,3-dimethyl-1,4-dioxide... 

Thieno[3,4-d]isothiazole, 2,3-dihydro-3-oxo-1,1-dioxide, 6, 989 biological activity, 6, 1024 Thieno[2,3-c]isothiazole-3-carboxylic acid synthesis, 6, 1023... 

Terephthalic acid has been obtained from a great many /)-disubstituted derivatives of benzene or cyclohexane by oxidation with permanganate, chromic acid, or nitric acid. The following routes appear to have preparative value from />-toluic acid, />-methylacetophenone,2 or dihydro-/)-tolualdehyde by oxidation with permanganate from f>-cymene by oxidation with sodium dichromate and sulfuric acid from />-dibromobenzene or from /i-chloro- or -bromobenzoic acid by heating at 250° with potassium and cuprous cyanides and from />-dibromo-benzene, butyllithium, and carbon dioxide. ... 

Selenium dioxide oxidation of 7,8-dihydro-5(6//)-quinolinone semicarbazone gave, in addition to the expected 4,5-dihydro selenadiazoloquinoline 95 (analogous to sulfur derivative 76), the oxidized l,2,3-selenadiazolo[4,5-/]quinoline 96, which, when heated to 210°C for 30 min, gave the dimeric [l,4]diselenino [2,3-/ 5,6-/ ]diquinoline (95JHC177). 

Bromo atom of ethyl (3S)-10-bromo-3-methyl-7-oxo-2,3-dihydro-7//-pyrido[l,2,3- fe]-l,4-benzothiazine-6-carboxylate was change for hetaryl groups with tributylstannyl derivatives of heterocycles in the presence of (Ph3P)2Pd(II)Cl2 in boiling toluene (OOMIPIO). 7-Aryl-5-oxo-2,3-dihydro-5//-pyrido[l,2,3- fe]-l,4-benzothiazine-6-carboxylates, 6-carboxamides and their 1,1-dioxide derivatives were prepared from 7-chloro derivatives in the... 

Aryl-5-oxo-2,3-dihydro-5//-pyrido[l,2,3- e]-l,4-benzothiazine-6-carbox-amides and their 1,1-dioxides were prepared from the respective... 

Chemical Name 3,4-dihydro-3-(phenylmethyl)-6-(trifluoromethyl)-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide... 

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