- Influence of the catalyst structure in the cycloaddition of isocyanates to oxiranes promoted by tetraarylstibonium cations
-
In the context of our work on electron deficient group 15 cations as Lewis acid catalysts, we have synthesized the triflate salts of a series of tetraarylstibonium cations of general formula [ArSbPh3]+ with Ar = Mes (4+), o-(dimethylamino)phenyl (5+), and o-((dimethylamino)methyl)phenyl (6+). These new cationic antimony derivatives, along with the known [Ph4Sb]+ (1+), 1-naphthyltriphenylstibonium (2+), and [(Ant)SbPh3]+ (3+), have been evaluated as catalysts for the cycloaddition of oxiranes and isocyanates under mild conditions. While all stibonium cations favor the 3,4-oxazolidinone products, the reactivities of 5+ and 6+ are hindered by the ancillary amino donor which quenches the Lewis acidity of the antimony center. A comparison of the other stibonium cations shows that 4+ is the most selective catalyst.
- Yang, Mengxi,Pati, Nilanjana,Bélanger-Chabot, Guillaume,Hirai, Masato,Gabba?, Fran?ois P.
-
supporting information
p. 11843 - 11850
(2018/09/10)
-
- Palladium-catalyzed synthesis of N-aryloxazolidinones from aryl chlorides
-
(Matrix presented) An efficient method for intermolecular N-arylation of oxazolidinones using Pd2dba3 and various phosphine ligands in the presence of a weak base is reported. The conditions allow the use of cheaper aryl chlorides containing functionalities such as enolizable ketones, amides, etc., which would be incompatible with other coupling methods. The coupling reaction can be used to prepare enantiopure N-aryl β-amino alcohols. Depending on the stereoelectronic nature of the aryl chloride, careful choice of ligand was necessary for the success of these reactions.
- Ghosh, Arun,Sieser, Janice E.,Riou, Maxime,Cai, Weiling,Rivera-Ruiz, Luis
-
p. 2207 - 2210
(2007/10/03)
-
- Iodine(V) reagents in organic synthesis. Part 3. New routes to heterocyclic compounds via o-iodoxybenzoic acid-mediated cyclizations: Generality, scope, and mechanism
-
The discovery and development of the o-iodoxybenzoic acid (IBX) reaction with certain unsaturated N-aryl amides (anilides) to form heterocycles are described. The application of the method to the synthesis of δ-lactams, cyclic urethanes, hydroxy amines, and amino sugars among other important building blocks and intermediates is detailed. In addition to the generality and scope of this cyclization reaction, this article describes a number of mechanistic investigations suggesting a single electron transfer from the anilide functionality to IBX and implicating a radical-based mechanism for the reaction.
- Nicolaou,Baran,Zhong,Barluenga,Hunt,Kranich,Vega
-
p. 2233 - 2244
(2007/10/03)
-