Dimethylformamide acetate hydrogen sulfate

The sodium and potassium salts of glutaconaldehyde are soluble only in polar solvents such as water, dimethyl sulfoxide, N,N-dimethylformamide, pyridine, and methanol. However, the stable tetrabutylammonium salt is soluble in relatively nonpolar solvents such as chloroform and ethyl acetate. It may be prepared from the potassium salt in the following manner. In a 1-1. Erlenmeyer flask equipped with a magnetic stirring bar are placed a solution of 13.6g. (0.1 mole) of crude glutaconaldehyde potassium salt in 200 ml. of water and a solution of 33.9 g. (0.1 mole) of tetrabutyl-ammonium hydrogen sulfate in 200 ml. of ice-cold water, the pH of wliich was adjusted to 10 by adding aqueous 2M sodium hydroxide. 

Tri-O-benzyl-D-arabinofuranose stirred at 0° with a mixture of ethanethiol and anhydrous Mg-sulfate satd. with HGl, and the product treated with benzoyl chloride in pyridine 4-0-benzoyl-2,3,5-tri-0-benzyl-D-arabinose diethyl di-thioacetal (Y 94%) added with Drierite to henzyl alcohol, stirred 1 hr. after addition of Cd-carbonate and HgClg the product isolated after 2 hrs. -> 4-0-benzoyl-2,3,5-tri-0-henzyl-D-arabinose dibenzyl acetal (Y 80%) stirred 16 hrs. under reflux at 56-58° with BaO, Drierite, methyl iodide, and dimethylformamide, the resulting crude 2,3,5-tri-0-henzyl-4-0-methyl-D-arabinose dibenzyl acetal hydrogenated ca. 2.5 hrs. with palladous chloride in methanol, and the product refluxed 1.5 hrs. in 0.5 N HGl to hydrolyze the methyl glycoside present 4-0-methyl-y -D-arabinopyranose (Y 64%). — This pathway is not dependent on the stereochemistry of the aldose. H. G. Fletcher, Jr., and H. W. Diehl, J. Org. Ghem. 30, 2321 (1965). 

A solution of 6-chloro-3,4-dihydro-4-methyl-3-oxo-2H-l,4-benzoxazine-8-carboxylic acid in tetrahydrofuran and dimethylformamide is cooled to below 0°C and triethylamine is added under stirring thereto. Further, ethyl chlorocarbonate is added and the mixture is stirred at room temperature. To the resultant mixture is added 3-amino-8-azabicyclo[3.2.1]octane and the mixture stirred. After completion of the reaction, aqueous sodium hydrogen carbonate and ethyl acetate are added. The organic layer is separated, washed with water and dried over magnesium sulfate. The solvent is distilled off to give 6-chloro-3,4-dihydro-4-methyl-N-(8-azabicyclo[3.2.1]oct-3-yl)-3-oxo-2H-l,4-benzoxazine-8-carboxamide. 

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