employing Knoevenagel condensation of 2,4,5-tri-O-acetyl-3-O-benzyl-aldehydo-D-xylose with dimethyl malonate as a key reaction. O-Deacetylation of 8 and successive glycol cleavage followed by acetylation gave a mixture of (1S,4R,5R,6R)-5-acetoxy-6-benzyloxy-4-methoxycarbonyl-2-oxobicyclo[2.2.1]heptan-3-one and dimethyl (2R,3R,4S)-2,4-diacetoxy-3-benzyloxy-1,1-cyclopentanedicarboxylate (12), which was converted
通过使用 2 的 Knoevenagel 缩合,将已知的 3-O-苄基-
D-木糖转化为甲基 (4R,5R,6R)-4,6,7-triacetoxy-5-benzyloxy-2-(甲氧基羰基)heptanoate (8) ,4,5-三-O-乙酰基-3-O-苄基-醛-
D-木糖与
丙二酸二甲酯作为关键反应。8 的 O-脱乙酰化和连续的
乙二醇裂解,然后乙酰化得到 (1S,4R,5R,6R)-5-乙酰氧基-6-苄氧基-4-甲氧基羰基-2-氧代
双环[2.2.1]庚烷-3-的混合物1 和 (2R,3R,4S)-2,4-diacetoxy-3-benzyloxy-1,1-cyclopentanedicarboxylate (12) 的二甲酯 (12),其仅转化为 12。这种对映体纯的高氧化
环戊烷二
羧酸酯 12 通过 1) 热脱甲氧基羰基化反应转化为 (3S,4S)-3-benzyloxy-1-(t-buty