Synthesis of Pyridines, Quinolines, and Pyrimidines via Acceptorless Dehydrogenative Coupling Catalyzed by a Simple Bidentate P^N Ligand Supported Ru Complex

Abstract

A ruthenium hydrido chloride complex (1) supported by a simple, heteroleptic bidentate P^N ligand (L1) containing a diarylphosphine and a benzannulated phenanthridine donor arm is reported. In the presence of base, complex 1 catalyzes multi-component reactions using alcohol precursors to produce structurally diverse molecules including pyridines, quinolines and pyrimidines via acceptorless dehydrogenative coupling pathways. Notably, L1 does not bear readily (de)protonated Brønsted acidic or basic groups common to transition metal catalysts capable of these sorts of transformations, suggesting metal-ligand cooperativity does not play a significant role in the catalytic reactivity of 1. A rare example of an h 2 -aldehyde adduct of ruthenium was isolated and structurally characterized, and its role in acceptorless dehydrogenative coupling reactions is discussed.

Catalytic Synthesis of Donor-Acceptor-Donor (D-A-D) and Donor-Acceptor-Acceptor (D-A-A) Pyrimidine-Ferrocenes via Acceptorless Dehydrogenative Coupling: Synthesis, Structures, and Electronic Communication

“…Figure 2) bearing a bidentate diarylphosphine/phenanthridine ligand which, in conjunction with a Brønsted base, can catalyze multicomponent reactions of alcohols and therefore be used to access a range of N-heterocycles including pyridines, quinolines, and pyrimidines. 42 The ligand scaffold in [Ru] is notable in that it does not contain readily (de)protonated Brønsted acidic or basic groups which tend to be common in transition metal catalysts capable of these sorts of transformations, precluding a role for metal-ligand cooperativity in the catalytic ADC-type reactivity of [Ru]. Instead, alcohol dehydrogenation produces η 2 -aldehyde adducts whose reluctance to dissociate free aldehyde is considered critical to the observed multicomponent reactivity.…”

“…Compared with ADC routes to polysubstituted pyridines and quinolines, relatively fewer studies have described the synthesis of pyrimidines via homogeneous catalysis. − Recently, we disclosed a simple ruthenium hydrido chloride complex ( [Ru] , Figure ) bearing a bidentate diarylphosphine/phenanthridine ligand which, in conjunction with a Brønsted base, can catalyze multicomponent reactions of alcohols and therefore be used to access a range of N -heterocycles including pyridines, quinolines, and pyrimidines . The ligand scaffold in [Ru] is notable in that it does not contain readily (de)­protonated Brønsted acidic or basic groups which tend to be common in transition metal catalysts capable of these sorts of transformations, precluding a role for metal-ligand cooperativity in the catalytic ADC-type reactivity of [Ru] .…”

Catalytic Synthesis of Luminescent Pyrimidines via Acceptor-less Dehydrogenative Coupling

“…[23][24][25][26][27][28] We recently described the preparation and reactivity of a ruthenium hydrido chloride complex (1) supported by a simple, heteroleptic bidentate P^N ligand containing a diarylphosphine and a benzannulated phenanthridine donor arm. 30 In the presence of base, complex 1 efficiently catalyzes multi-component reactions using alcohol precursors to produce structurally diverse molecules including pyridines and quinolines.…”

Transition-metal-free synthesis of pyrimidines from lignin β-O-4 segments via a one-pot multi-component reaction

“…Hence, assembling a pyrimidine core has driven considerable investigations. Extensive studies have focused on amidine reactions with coupling partners such as 1,3-dicarbonyl derivatives, α,β-unsaturated ketones, alkynones, 1,2,3-triazines 28 , and alcohols in the presence of organometallic catalysts based on Ir 29 , Ru 30 , Re 31 , Mn 32 , 33 , and Ni 34 . However, most of the methods described so far suffer from employing transition metal catalysts and additives, with complicated ligands, and using non-renewable substrates.…”