Rh^III‐Catalyzed Oxidative Olefination of Vinylic CH Bonds: Efficient and Selective Access to Di‐unsaturated α‐Amino Acid Derivatives and Other Linear 1,3‐Butadienes

Abstract

The family of AZARYPHOS (aza–aryl–phosphane) phosphane ligands, containing a phosphine unit and sterically shielded nitrogen lone pairs in the ligand periphery, is introduced as a tool for developing ambifunctional catalysis by the metal center and nitrogen lone pairs in the ligand sphere. General synthetic strategies have been developed to synthesize over 25 examples of structurally diverse (6‐aryl‐2‐pyridyl)phosphanes (ARPYPHOS), (6‐alkyl‐2‐pyridyl)phosphanes (ALPYPHOS), 4,6‐disubsituted 1,3‐diazin‐2‐ylphosphanes or 1,3,5‐triazin‐2‐ylphosphanes, quinazolinylphosphanes, quinolinylphosphanes, and others. The scalable syntheses proceed in a few steps. The incorporation of AZARYPHOS ligands (L) into complexes [RuCp(L)2(MeCN)][PF6] (Cp=cyclopentadienyl) gives catalysts for the anti‐Markovnikov hydration of terminal alkynes of the highest known activities. Electronic and steric ligand effects modulate the reaction kinetics over a range of two orders of magnitude. These results highlight the importance of using structurally diverse ligand families in the process of developing cooperative ambifunctional catalysis by a metal and its ligand.

Palladium-Catalyzed Intermolecular Oxidative Amination of Alkenes with Amines, Using Molecular Oxygen as Terminal Oxidant

“…functional groups directly connected to the C=C bonds of olefins [4][5][6][7][8][9]. Oxidative coupling for the formation of nitrogen-containing compounds such as enamines using metal-catalyzed oxidative amination of olefins by dioxygen, known as the aza-Wacker reaction, has been the subject of considerable research [10][11][12][13][14][15][16][17][18].…”

“…To confirm the participation of the η 3 -allylpalladium intermediate as the key in the catalytic cycle, and in order to obtain further insights into the specific role of the Pd(OCOCF 3 ) 2 catalyst in this reaction, the (η 3 -cinnamyl)palladium trifluoroacetate dimer (7) and (η  -cinnamyl)palladium acetate dimer (8) were synthesized independently as model intermediates, according to the literature methods [61,62]. Stoichiometric reactions with diphenylamine (1) were carried out under the conditions shown in Equation 5, using the complexes 7 and 8.…”

Rh(III)- and Ir(III)-Catalyzed C–C Bond Cross Couplings from C–H Bonds

“…The first step in this field using a Rh-based catalyst was achieved by Glorius in 2011 realizing an oxidative Heck reaction between vinylic substrates bearing various DGs (amide, ester, etc.) and activated olefins (acrylates and styrenes) (7) [88]. The desired products were obtained in good to moderate yields, but with encouraging Z-selectivity.…”

Palladium-catalyzed cross-coupling of cyclopropylmethyl N-tosylhydrazones with aromatic bromides: an easy access to multisubstituted 1,3-butadienes

“…3 The cross-coupling of two alkenyl species is the most direct procedure, including that mediated by palladium 4 and rhodium. 5 Transition metal-catalyzed hydrovinylation of alkynes is a commendable protocol to stereoselectively prepare 1,3-dienes. 6 Carbonyl alkenylation involving the Wittig reaction or its variants has been applied for this purpose.…”