1-Deoxy-D-xylulose (4) and the corresponding 5-phosphate (5) are substrates for the first pathway-specific enzymes in the biosynthesis of thiamine diphosphate (vitamin B(1)), pyridoxol phosphate (vitamin B(6)), and the nonmevalonate family of isoprenoid compounds recently discovered in bacteria and plant chloroplasts. Both 4 and 5 were synthesized from commercially available (-)-2,3-O-isopropylidene-D-threitol (10). The protected tetraol was converted to (-)-3,4-O-isopropylidene-5-triisopropylsilyl-1-deoxy-D-xylulose (14) in four steps. Treatment of 14 with acetic acid gave 4 in an overall yield of 69%. The corresponding 5-phosphate was obtained by protection the carbonyl group in 14, removal of the triisopropylsilyl moiety, and treatment of the resulting alcohol with trimethyl phosphite/TeCl(4), trimethylsilyl bromide, water, and HCl in successive steps to give 5 in 58% overall yield from 10.