Asymmetric Synthesis of Unsaturated Monocyclic and Bicyclic Nitrogen Heterocycles
摘要:
Hydrolysis of scalemic trichloroacetamides Cl3CCONHCH(R)CHCH2 and allylation, or acylation with but-3-enoic acid, followed by ring-closing metathesis resulted in the formation of unsaturated pyrrolidine and piperidine building blocks. These were employed in the synthesis of (S)-coniine (R = Pr) and a formal synthesis of (+)-anisomycin (R = p-MeOC5H4). Extension of this methodology with R = CH2CHCH2 employing two ring-closing metatheses resulted in the synthesis of unsaturated quinolizidinone and indolizidinone frameworks.
(η 5 -( N , N -二甲氨基甲基)环戊二烯基)(η 4 -四苯基环丁二烯)钴与四氯钯酸钠和( R ) -N -乙酰基苯丙氨酸反应得到平面手性环钯二-μ-氯化双[(η 5 - ( S p )-2-( N , N-二甲基氨基甲基)环戊二烯基,1- C ,3′- N )(η 4 -四苯基环丁二烯)钴]二钯[( S p )-Me 2 -CAP-Cl],92 % ee和 64% 的产率。通过纯化单体 ( R )-脯氨酸加合物并转化回氯化物二聚体,实现对映体纯度 (>98% ee )。AgOAc 处理得到 ( S p )-Me 2 -CAP-OAc,将其应用于不对称转环钯化(高达 78 % ee)。( R )-N-乙酰基苯丙氨酸介导的钯化方法也适用于相应的N , N-二乙基(82% ee,产率 39%)和吡咯烷基(>98% ee,产率 43%)钴夹心配合物。5 mol % 的后者 [( S p
An Investigation into the Allylic Imidate Rearrangement of Trichloroacetimidates Catalysed by Cobalt Oxazoline Palladacycles
作者:Hiroshi Nomura、Christopher J. Richards
DOI:10.1002/chem.200700873
日期:2007.12.17
3'-N}(eta(4)-tetraphenylcyclobutadiene)cobalt]dipalladium (COP-X), containing bridging groups X=OAc, Cl, Br, I, O(2)CCF(3), p-O(2)CC(6)H(4)F, were synthesised and compared as catalysts for the asymmetric allylicimidaterearrangement of (E)-Cl(3)CC(=NH)OCH(2)CH=CHR with R=nPr. The enantiomeric excess of the product (S)-Cl(3)CC(=O)NHCHRCH=CH(2) was essentially invariant of X (93-96%) and the yield increased