P,N ligands in asymmetric catalysis

Abstract

P,N ligands are an important class of ligands for asymmetric catalysis. In this tutorial review an up to date account of recent applications of these ligands in asymmetric catalysis is presented. A special focus is given to newer classes of ligands and the application of more established P,N ligands in novel reactions.

Increasing Complexity: A Practical Synthetic Approach to Three‐Dimensional, Cyclic Sulfoximines and First Insights into Their in Vitro Properties

“…The synthetic applicability of bromo-substituted products such as 3ah for metal-catalyzed cross-coupling reactions has already been demonstrated by Bolm and co-workers. [11] ortho-Iodo derivative 3ai was envisaged to allow access to P, Nl igands [20] by cross-coupling with suitable phosphanes. [21] Prepa-ration of the matched pyridyl analogueso fp henyl derivative 3ab provedt ob ed ifficult due to very high polarity and solubility of the corresponding products, which hampered preparative isolation.H owever,t he feasibility of heterocyclic substituents R 1 is displayed in products 3al and 3am.M oreover,s tarting from 3-sulfanylestra-1(10),2,4-trien-17-one, [22] the applicability of the three-step procedure for complex, drug-like molecules is demonstrated by the formation of 3an (1:1 mixture of diastereomers) in high overall yield.…”

Application of 1,3‐Dipolar Reactions between Azomethine Ylides and Alkenes to the Synthesis of Catalysts and Biologically Active Compounds

“…This conformationally restricted environment can be achieved by means of chiral ligands possessing donor atoms. Among the different possibilities, enantiopure ligands bearing phosphine and amine functional groups (P,N‐ligands) constitute the most efficient L* groups that can promote asymmetric catalytic (3+2) cycloadditions between azomethine ylides and alkenes. Within this context, ferrocenylphosphine groups incorporating five‐membered nitrogen‐containing heterocycles are especially relevant because of the interplay between the planar chirality of the ferrocenyl moiety and the central chirality of the heterocycle.…”

“…We reasoned that ferrocenylphosphino pyrrolidines bearing four chiral centers after (3+2) cycloadditions could constitute promising P,N‐ligands in which the high density of chiral centers would in turn catalyze with high stereocontrol other (3+2) cycloadditions between azomethine ylides and nitroalkenes. The synthesis of these P,N‐ligands started with enantiomerically pure ferrocenyl carboxaldehyde 19 prepared according the method described by Kagan et al (Scheme ).…”

Preparation and characterisation of a Ni2+/Co2+-cyclam modified mesoporous cellular foam for the specific immobilisation of His6-alanine racemase

“…However, to select appropriate ligands, some criteria points should be observed; the solubility of the active species, ability to associate/dissociate and mostly importantly coordinate to metals 137 . The ligands can be divided into two type depending on the metal coordinate: (i) monodentate ligands coordinate to the metal through a single bond 138 e.g phosphorous (P), oxygen (O), nitrogen (N) and carbon (C); (ii) chelating ligands are ligands that coordinate to the metal through two or more bonds, and include ligands cyclam, 1,4,7-triazzcyclonanane and salen ligand.…”