描述了由方酸二甲酯2a合成方酸N-羟基酰胺酯5和酰胺6。这些衍生物是天然存在的铁(III)螯合剂异羟肟酸的类似物。在比较反应性研究的基础上,提出了一种协调的逆-Cope机理,该机理通过使方酸二甲酯与羟胺反应形成N-羟酰胺酯5。提出了对这些异羟肟酸类似物的铁(III)结合的初步研究,表明铁(III)与水溶液中的酰胺6结合,而酯5没有显示出任何金属离子结合的迹象。这些和相关衍生物的13 C NMR光谱数据(化学位移和自旋晶格弛豫时间测定)描绘了这些分子中主要的共振结构。衍生物的共振结构使它们的光谱数据,化学反应性和铁(III)结合特性合理化。方酸N-羟基酰胺酯5b和方酸N-羟基酰胺酰胺6c的单晶X射线结构分析证实了它们的连通性,并提供了支持光谱学得出结论的结构证据。方酸N-羟基叠氮化物可潜在地用于构建铁(III)的化学传感器。
motifs in organocatalysis, whereas efficient 1,3‐diamine‐derived organocatalysts are very rare. Herein we report a highly efficient camphor‐1,3‐diamine‐derived squaramideorganocatalyst. Its catalytic activity in Michaeladditions of 1,3‐dicarbonyl nucleophiles to trans‐β‐nitrostyrene derivatives provides excellent enantioselectivities (up to >99% ee).
Ferrocene Analogues of Hydrogen-Bond-Donor Catalysts: An Investigative Study on Asymmetric Michael Addition of 1,3-Dicarbonyl Compounds to Nitroalkenes
作者:Rajiv Trivedi、Kadiyala Rao、M. Kantam
DOI:10.1055/s-0034-1379491
日期:——
moieties. A stepwise sequential route was used to assemble the various components of these ferrocene derivatives. The resulting bifunctional catalysts were used successfully in asymmetric Michael additions of 1,3-dicarbonylcompounds to β-nitrostyrenes. The corresponding products were obtained in high yields and in good to excellent enantioselectivities and diastereoselectivities under mild conditions by
Development of Chiral, Bifunctional Thiosquaramides: Enantioselective Michael Additions of Barbituric Acids to Nitroalkenes
作者:Michael Rombola、Chintan S. Sumaria、Thomas D. Montgomery、Viresh H. Rawal
DOI:10.1021/jacs.7b01115
日期:2017.4.19
nonpolar solvents than their oxosquaramide counterparts, and they are excellent catalysts for the unreported, enantioselective conjugate addition reaction of the barbituric acid pharmacaphore to nitroalkenes, delivering the chiral barbiturate derivatives in high yields and high enantioselectivities, even with catalyst loadings as low as 0.05 mol%.
Synthesis and evaluation of cationic norbornanes as peptidomimetic antibacterial agents
作者:Shane M. Hickey、Trent D. Ashton、Simren K. Khosa、Ryan N. Robson、Jonathan M. White、Jian Li、Roger L. Nation、Heidi Y. Yu、Alysha G. Elliott、Mark S. Butler、Johnny X. Huang、Matthew A. Cooper、Frederick M. Pfeffer
DOI:10.1039/c5ob00621j
日期:——
A series of structurally amphiphilic biscationic norbornanes have been synthesised as rigidified, low molecular weight peptidomimetics of cationic antimicrobial peptides. A variety of charged hydrophilic functionalities were attached to the norbornane scaffold including aminium, guanidinium, imidazolium and pyridinium moieties. Additionally, a range of hydrophobic groups of differing sizes were incorporated
Bifunctional Iminophosphorane-Catalyzed Enantioselective Sulfa-Michael Addition to Unactivated α,β-Unsaturated Amides
作者:Daniel Rozsar、Michele Formica、Ken Yamazaki、Trevor A. Hamlin、Darren J. Dixon
DOI:10.1021/jacs.1c11898
日期:2022.1.19
unactivated α,β-unsaturatedamides is described. Consistently high enantiomeric excesses and yields were obtained over a wide range of alkyl thiol pronucleophiles and electrophiles under mild reaction conditions, enabled by a novel squaramide-based bifunctional iminophosphorane catalyst. Low catalyst loadings (2.0 mol %) were achieved on a decagram scale, demonstrating the scalability of the reaction. Computational