PREPARATION OF SUGAR-DERIVED BETA-KETO PHOSPHONATES AND THEIR USE IN THE SYNTHESIS OF HIGHER SUGARS

Sugar-derived beta-keto phosphonates 5, 6, 7, and 8 were synthesised by the acylation of lithium dimethyl methylphosphonate with the corresponding methyl glycuronates 1, 2, and 3 and glyconate 4 in THF at -78 degrees C, respectively. Wadsworth-Emmons reaction of 5, 6, 7, and 8 with various sugar-derived aldehydes proceeded in good yield to produce higher sugar enones. Similarly, C-2 symmetric bis phosphonate 28 derived from L-tartrate 27 was prepared and condensed with various sugar-derived aldehydes to provide C-2 symmetric bis enones in moderate yields. Treatment of the glucose-derived beta-keto phosphonate 5 with various aldehydes and excess Cs2CO3 resulted in complete cis elimination of the C-4 benzyl group along with the Wadsworth-Emmons reaction, leading to cross-conjugated dienones.