New Building Block for Polyhydroxylated Piperidine: Total Synthesis of 1,6-Dideoxynojirimycin
作者:Rajesh Rengasamy、Marcus J. Curtis-Long、Woo Duck Seo、Seong Hun Jeong、Ill-Yun Jeong、Ki Hun Park
DOI:10.1021/jo702480y
日期:2008.4.1
(3R,4S)-3-Hydroxy-4-N-allyl-N-Boc-amino-1-pentene 10, an important precursor for the synthesis of polyhydroxylated piperidines, has been achieved as a single diastereomer without racemization via vinyl Grignard addition to N-Boc-N-allyl aminoaldehyde 9, which was derived from an enantiopure natural amino acid. Having forged a tetrahydropyridine ring scaffold 13 from 10 in 85% yield via RCM using Grubbs II catalyst, we were able to effect its stereo-divergent dihydroxylation, via a common epoxide intermediate to yield a range of interesting hydroxylated piperidines, including ent-1,6-dideoxynojirimycin (ent-1,6-dDNJ) 1 (28% overall yield) and 5-amino-1,5,6-trideoxyaltrose 2 (29% over all yield) in excellent dr. To the best of our knowledge, our synthesis of ent-1,6-dDNJ 1 is the most expeditious to date.
(3R,4S)-3-羟基-4-N-烯丙基-N-Boc-氨基-1-戊烯 10 是一种重要的聚羟基哌啶类化合物合成前体, 通过乙烯格氏加成反应由对映纯天然氨基酸衍生的 N-Boc-N-烯丙基氨基乙醛 9 制得, 成品为单一双相异构体且无消旋化现象。采用格拉布催化剂II 进行环化复分解反应(RCM), 由10 得到四氢吡啶环骨架13, 收率85%。随后, 经过相同环氧中间体, 我们实现了四氢吡啶环骨架13的立体发散性双羟基化, 得到一系列有趣的羟基化哌啶类化合物, 包括ent-1,6-去氧诺吉霉素(ent-1,6-dDNJ)1 和5-氨基-1,5,6-三去氧赤霉糖 2, 其中ent-1,6-dDNJ的总体收率为28%,5-氨基-1,5,6-三去氧赤霉糖的收率为29%, 均具有优秀的非对映异构体比率。据我们所知, 我们的ent-1,6-dDNJ合成路线是到目前为止最为高效的。