[reaction: see text] Allylzirconium reagents are effective for radicalallylation of alpha-halo carbonyl compounds. The key steps would be homolytic cleavage of the zirconium-carbon bond and halogen abstraction by the resulting Cp(2)ZrCl(III). Zirconocene-olefin complex can be also utilized for the allylation of alpha-halo compounds.
A protocol for highly enantioselectivehydrogenation of racemic α-arylamino lactones with catalysis by site-specifically modified chiral spiro iridium complexes has been developed. With the optimized catalyst, racemic α-arylamino-γ-lactones and α-arylamino-δ-lactones could be hydrogenated to the corresponding chiral 2-amino diols with good to excellent enantioselectivities.
Synthetic Studies Towards the Core Structure of Nakadomarin A by a Thioamide-Based Strategy
作者:Jai K. Chavda、Panayiotis A. Procopiou、Peter N. Horton、Simon J. Coles、Michael J. Porter
DOI:10.1002/ejoc.201301063
日期:2014.1
The tricyclic BCD substructure of the marine natural product nakadomarin A has been synthesised. The strategy utilised a key carbon–carbon bond-forming reaction between a furan and an N-acyliminium ion derived from a secondary thiolactam. In addition, a novel three-component coupling reaction between a thioamide, an allylic bromide and an isocyanate, leading to the establishment of two new stereogenic
已合成海洋天然产物 nakadomarin A 的三环 BCD 亚结构。该策略利用了呋喃和衍生自二级硫内酰胺的 N-酰基胺离子之间的关键碳-碳键形成反应。此外,还报道了硫代酰胺、烯丙基溴和异氰酸酯之间的新型三组分偶联反应,导致建立两个新的立体中心。通过使用硫代酰胺的独特化学,已经实现了 nakadomarin A 计划全合成的两个关键步骤。碳环 B 环的形成可以通过呋喃对硫内酰胺衍生的亚胺离子的亲核攻击来实现,并且关键的季铵中心可以通过新型的三组分偶联反应建立。
Phosphazene-catalyzed intramolecular cyclization of nitrogen-tethered alkynyl esters
作者:Azusa Kondoh、Kenichi Ando、Masahiro Terada
DOI:10.1039/c3cc46100a
日期:——
Intramolecularcyclization of nitrogen-tethered alkynyl esters catalyzed by phosphazene organosuperbases P2-tBu and P4-tBu was investigated. Both acyclic and cyclic substrates underwent 5-exo-dig and 5-endo-dig cyclization. This reaction is a rare example of the intramolecular addition of enolates of simple esters to alkynes.