An unsaturated ketohexose and derived hexenetetrols

The unsaturated ketose, 3,4-dideoxy-D-glycero-hex-trans-3-enulose, was prepared from 3-deoxy-2-O-methyl-β-D-erythro-hex-2-enofuranose by reduction with sodium borohydride followed by an allylic rearrangement under mild acid conditions. Further reduction of the ketose with sodium borohydride yielded erythro- and D-threo-hex-trans-3-ene-1,2,5,6- tetrols. The 1,2:5,6 di-O-isopropylidene derivatives of the tetrols were also prepared. The main evidence for the trans configuration of the double bonds of these five compounds is that they have a large value for J3.4 (15.4-16.4 c/s).