The Carbohydrate-Sesquiterpene
Interface. A Zirconocene-Mediated Synthesis of (+)-Epiafricanol
from <scp>d</scp>-Glucose
作者:Leo Paquette、Ruslan Arbit、Jacques-Alexis Funel、Sergei Bolshakov
DOI:10.1055/s-2002-34380
日期:——
A total synthesis of (+)-epiafricanol (6) has been readily achieved from d-glucose. The tricyclic alcohol target was arrived at by first forming methyl 6-O-benzyl-2-deoxy-2-C-methyl-α-d-altropyranoside (12) and converting this intermediate into methyl 2-C-methyl-2,3,4-trideoxy-α-d-threo-hexopyranoside (14). There followed a series of steps resulting in extension of the side chain to give the isopropenyl pyranoside 9. This advanced intermediate was subjected to zirconocene-promoted ring contraction, which gave rise to 8 and set the stage for conversion to 7. This tertiary carbinol was transformed into 6 by sequential ring-closing metathesis and stereodirected Simmons-Smith cyclopropanation.
(+)-epiafricanol (6) 很容易从 d-葡萄糖中完全合成。 首先形成甲基 6-O-苄基-2-脱氧-2-C-甲基-δ-d-altropyranoside (12),然后将该中间体转化为甲基 2-C-甲基-2,3,4-三脱氧-δ-±-d-苏-吡喃糖苷 (14),从而达到三环醇的目标。经过一系列步骤,侧链得到延伸,从而得到异丙烯基吡喃糖苷 9。这种高级中间体经过锆碳烯促进的环收缩,产生了 8,为转化成 7 创造了条件。通过连续的闭环偏析和立体定向 Simmons-Smith 环丙烷化反应,这种三级甲醇被转化为 6。