Synthesis of (+)-1,3:2,5-dianhydroviburnitol ((+)-(1R,2R,3S,5R,6S)-4,7-dioxatricyclo[3.2.1.03,6]octan-2-ol)
作者:Claude Le Drian、Pierre Vogel
DOI:10.1002/hlca.19880710604
日期:1988.9.28
Epoxidation of (−)-(1R,2R,4R)-2-endo-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-exo-yl acetate ((−)-5) followed by saponification afforded (+)-(1R,4R,5R,6R)-5,6-exo-epoxy-7-oxabicyclo[2.2.1]heptan-2-one ((+)-7). Reduction of (+)-7 with diisobutylaluminium hydride (DIBAH) gave (+)-1,3:2,5-dianhydroviburnitol ( = (+)-(1R,2R,3S,4R,6S)-4,7-dioxatricyclo[3.2.1.03,6]octan-2-ol; (+)-3). Hydride reductions of (±)-7
(-)-(1 R,2 R,4 R)-2-内-氰基-7-氧杂双环[2.2.1]庚-5-烯-2-乙酸异戊酯的环氧化((-)-5)随后进行皂化,得到(+)-(1 R,4 R,5 R,6 R)-5,6-外-环氧--7氧杂双环[2.2.1]庚烷-2-酮((+)-7) 。用氢化二异丁基铝(DIBAH)还原(+)-7得到(+)-1,3:2,5-二氢紫杉醇(=(+)-(1 R,2 R,3 S,4 R,6 S)- 4,7-二氧杂三环[3.2.1.0 3,6 ]辛烷-2-醇;(+)-3)。(±)-7不太的氢化物还原外面取向选择性比双环的减量[2.2.1]庚烷-2-酮和其用NaBH衍生物4,的AlH 3,和的LiAlH 4大概是因为较小的空间位阻内切-面氢化攻击时C(5)和C( 6)的双环[2.2.1]庚烷-2-酮是外环氧乙烷环的一部分。