The existing synthetic methods of 3, 4, 6-tri-O-acetyl-1, 2-O-ethylidene -β-D- mannopyranose, 1, 2-O-ethylidene -β-D- mannopyranose, 4, 6-O- benzylidene-1, 2-O-ethylidene -β-D- mannopyranose were modified in this paper. And the same time they were synthesized by the microwave assisted method firstly, and the best results were got by orthogonal experiment based on single factor investigation. Their optimum technology of synthesis were 600 W, 3.5 h, 35 ℃, mass of sodium borohydride 2.5 g;600 W, 30 min, 30 ℃, mass of sodium methoxide 0.4 g;800 W, 1.5 h, 35 ℃, mass of p-methylbenzene sulfonic acid 0.2 g. Their optimized yield were 80.3%、98.3%、91.9%.
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