6-thio- and -seleno-D-galactose esters of dimethylarsinous acid

The syntheses of 1,2:3,4-di-O-isopropylidene-6-S-dimethylarsino-6-thio-α-D-galactopyranose (2), methyl 6-S-dimethylarsino-6-thio-D-galactopyranoside (3), and 1,2:3,4-di-O-isopropylidene-6-Se-dimethylarsino-6-seleno-α-D-galactopyranose (8) are reported. The attempted preparation of 6-Se-dimethylarsino-6-seleno-D-galactopyranose (9) is also discussed. The n.m.r. spectra of these compounds are unexceptional, except for the slight downfield shift of the arsenic methyl resonances for the selenium compound as compared to the sulfur compound, confirming previous observations. The mass spectra of these compounds showed molecular ions for 2, 3, and 8. The u.v. spectra of the X-As (X = S, Se) chromophore are discussed in terms of a simplified MO model. 1,2:3,4-Di-O-isopropylidene-6-S-dimethylarsino-6-thio-α-D-galactopyranose (2) showed carcinostatic activity in the P388 system (mouse lymphocytic leukemia).