Racemic dimethyl 4-methoxy- (11 and 12), diallyl 4-allyloxy- (13 and 14) and dimethyl 4-(ethylsulfanyl)-2-hydroxycyclopentane-1,1-dicarboxylates (15 and 16) were prepared by base-catalyzed addition of methanol, allyl alcohol and ethylsulfane, respectively, to dimethyl (4-oxobut-2-en-1-yl)malonate (6). Deallylation of 13 and 14 afforded 4-hydroxycyclopentanes 27 and 28. Reduction of 11-16 with lithium aluminium hydride gave the corresponding 4-substituted 2,2-bis(hydroxymethyl)cyclopentanols. Dimethyl (2S,3S,4R)-, (2R,3S,4R)-3-benzyloxy-4-formyloxy-2-hydroxycyclopentane-1,1-dicarboxylates (35, 36) and dimethyl (2S,3S,4R)-, (2R,3S,4R)-3-benzyloxy-2-benzoyloxy-4-methoxycyclopentane-1,1-dicarboxylates (39, 40) were synthesized starting from D-glucose. Reduction of dimethyl cyclopentane-1,1-dicarboxylates 39 and 40 with lithium aluminium hydride, benzoylation of the formed hydroxy derivatives, hydrogenolysis of benzyl groups, conversion of the liberated hydroxy groups into dithiocarbonates and their reduction with tributylstannane afforded, after removal of the protecting groups, (2R,4R)-1,1-bis(hydroxymethyl)-4-methoxycyclopentan-2-ol ((2R,4R)-17) and (3R,4R)-1,1-bis(hydroxymethyl)-4-methoxycyclopentan-3-ol (51). Reduction of a mixture of esters 35 and 36 gave (2R,3R)-2-benzyloxy-5-(hydroxymethyl)hexane-1,3,6-triol (52) as the major product and (2R,3S,4R)-3-benzyloxy-1,1-bis(hydroxymethyl)cyclopentane-2,4-diol (53) as the minor product. The latter was converted into (3R,4R)-1,1-bis(hydroxymethyl)cyclopentane-3,4-diol (58). 3-Deoxycarba analogues 51 and 58 arose by migration of benzoyl group in the preparation of the dithiocarbonates.
通过碱催化加入
甲醇、
烯丙醇和
乙硫醇到二
甲基(4-
氧代丁-2-
烯-1-基)
丙二酸酯(6)中,制备了外消旋二
甲基4-甲氧基-(11和12)、
二烯丙基4-
烯丙
氧基-(13和14)和二
甲基4-(乙
硫基)-2-羟基
环戊烷-1,1-二
羧酸酯(15和16)。去
烯丙基化13和14得到
4-羟基
环戊烷27和28。用
铝锂还原11-16得到相应的4-取代的
2,2-双(
羟甲基)
环戊烷醇。从
D-葡萄糖开始合成二
甲基(2S,3S,4R)-、(2R,3S,4R)-3-苄
氧基-4-甲酰
氧基-2-羟基
环戊烷-1,1-二
羧酸酯(35,36)和二
甲基(2S,3S,4R)-、(2R,3S,4R)-3-苄
氧基-2-
苯甲酰
氧基-
4-甲氧基环戊烷-1,1-二
羧酸酯(39,40)。用
铝锂还原二
甲基环戊烷-1,1-二
羧酸酯39和40,
苯甲酰化形成羟基衍
生物,
苯甲基的
氢解,将释放的羟基转化为二
硫代
碳酸酯,再用三
丁基锡还原,去除保护基后得到(2R,4R)-1,1-双(
羟甲基)-
4-甲氧基环戊烷-2-醇((2R,4R)-17)和(3R,4R)-1,1-双(
羟甲基)-
4-甲氧基环戊烷-3-醇(51)。混合
酯35和36还原后,主要产物为(2R,3R)-2-苄
氧基-5-(
羟甲基)己烷-1,3,6-三醇(52),次要产物为(2R,3S,4R)-3-苄
氧基-1,1-双(
羟甲基)-
环戊烷-
2,4-二醇(53)。后者被转化为(3R,4R)-1,1-双(
羟甲基)-
环戊烷-3,4
-二醇(58)。在制备二
硫代
碳酸酯时,
苯甲酰基的迁移导致3-去
氧卡巴类似物51和58的形成。