Dimethylformamide dimethyl hydroxy acids

An OH and a COOH group can be eliminated from (3-hydroxy carboxylic acids by refluxing with excess dimethylformamide dimethyl acetal.363 Mono-, di-, tri-, and tetrasub-stituted olefins have been prepared by this method in good yields.364 There is evidence that the mechanism involves El or E2 elimination from the zwitterionic intermediate... 

A mixture of o-hydroxyacetophenone, dimethylformamide dimethyl acetal, and abs. xylene heated to 120 bath temp, with distillation of methanol, after ca. 2 hrs. the temp, raised to 150-160 for 0.5 hr., then allowed to stand overnight o-hydroxy-co-dimethylaminomethyleneacetophenone (Y 80%) heated 75 min. at 100 bath temp, with aq. H2SO4 chromone (Y 71%). B. Fohlisch, B. 104, 348 (1971) aminomethylenemalonic acid esters (cf. Synth. Meth. 25, 759) by C-dimethylaminomethylenation s. N. D. Harris, Synthesis 1971, 220. 

Amino-l, 3-dimethyl-6-phenylpyrrolo[2,3-d]pyrimidine-2,4(1H, 3H)-dione heated 3 hrs. at 65° with excess Pb-tetraacetate in dimethylformamide or acetic acid -> 1,3-dimethyl -5-hydroxy-7-phenylpyrimido[4,5-d] pyrimidine-2,4(1H, 3H)-dione. Y 90%. F. e. s. F. Yoneda and M. Higuchi, Chem. Commun. 1972, 402. 

Multzer s group has applied the dehydrative decarboxylation of (3-hydroxy-acids to the synthesis of buta-l,3-dienes. Thus, the addition of acetate anion to the a -unsaturated ketone (204) followed by reaction with dimethylformamide dimethyl acetal affords the ( )-dienes (205) stereospecifically, in high yields... 

The flask containing the solution of the (+)-(3aS,7aS)-2,3,3a,4,7,7a-hexahydro-3a-hydroxy-7a-methyl-lH-indene-1,5(6H)-dione in N,N-dimethyl -formamide is placed 1n an oil bath and heated to 95°C. When the temperature reaches 70-75°C, an 18.8-mL aliquot of the coned sulfuric acid in N,N-dimethylformamide solution is added in one portion. The reaction mixture is heated to 95°C for 3.0 hr. After 1.0 hr, an additional 7.5-mL aliquot of the coned sulfuric acid in N,N-dimethy1formamide solution is added in one portion. The reaction is monitored for completeness by GLC (Note 15) and cooled. The solvent is removed on a rotary evaporator at 45°C (0.3-0.5 ran) to give a brown oil. The material is taken up in 375 mL of dlchloromethane. The solution is washed with two 190-mL portions of 2.0 N sulfuric acid solution which have been saturated with sodium chloride, two 190-mL portions of saturated sodium bicarbonate solution which have been saturated with sodium chloride and 190 mL of saturated brine. Each aqueous wash is extracted, in turn, with the same two 190-mL portions of dichloromethane. The combined dichloromethane solutions are dried over sodium sulfate, filtered, and the solvent is removed on a rotary evaporator at 40°C (70 mm) to give 38.8-39.6 g of oily, brown semisolid. This material is taken up in 78 mL of ethyl acetate and the solution is applied to a dry column of 78 g of silica gel (Note 16). The column is eluted with 600 mL of ethyl acetate and the total eluate is... 

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