Sustainable Synthesis of Quinolines and Pyrimidines Catalyzed by Manganese PNP Pincer Complexes

Abstract

This study represents the first example an environmentally benign, sustainable, and practical synthesis of substituted quinolines and pyrimidines using combinations of 2-aminobenzyl alcohols and alcohols as well as benzamidine and two different alcohols, respectively. These reactions proceed with high atom efficiency via a sequence of dehydrogenation and condensation steps that give rise to selective C-C and C-N bond formations, thereby releasing 2 equiv of hydrogen and water. A hydride Mn(I) PNP pincer complex recently developed in our laboratory catalyzes this process in a very efficient way. A total of 15 different quinolines and 14 different pyrimidines were synthesized in isolated yields of up to 91 and 90%, respectively.

Homogeneous Catalysis by Manganese‐Based Pincer Complexes

“…Furthermore, the same group reported the synthesis of substituted quinolones through dehydrogenative coupling of 2‐aminobenzyl alcohol and different secondary aromatic or cyclic aliphatic alcohols, indan‐1‐ol or heterocyclic alcohols (Scheme ) As catalysts they tested not only 42 and 43 , but also complex 47 , as well as similar complexes with a triazine backbone ( 12a and 12c ) reported by Kempe. Once more, the N ‐methylated complex 43 did not show any activity, which demonstrates the importance of the NH proton during the catalytic reaction cycle.…”

Manganese‐Catalyzed Direct Olefination of Methyl‐Substituted Heteroarenes with Primary Alcohols

“…[15] In this regard, manganese,a st he third most abundant transition metal, has appeared as an attractive alternative. [17] Subsequently,m anganese complexes were utilized for catalytic dehydrogenations of methanol to CO 2 and H 2 , [18] dehydrogenative Nformylations of amines, [19] couplings of alcohols to esters, [20] syntheses of imines, [21] quinolines, [22] pyrimidines, [22,23] pyrroles, [24] cyclic imides, [25] amides, [26] and a,bunsaturated nitriles, [27] as well as hydrogenations of polar double bonds. [17] Subsequently,m anganese complexes were utilized for catalytic dehydrogenations of methanol to CO 2 and H 2 , [18] dehydrogenative Nformylations of amines, [19] couplings of alcohols to esters, [20] syntheses of imines, [21] quinolines, [22] pyrimidines, [22,23] pyrroles, [24] cyclic imides, [25] amides, [26] and a,bunsaturated nitriles, [27] as well as hydrogenations of polar double bonds.…”

Manganese‐Catalyzed Sustainable Synthesis of Pyrroles from Alcohols and Amino Alcohols

“…[10] Aside from the conservation of our fossil carbon resources,t he conservation of rare noble metals,w hich are frequently used in key technologies such as catalysis,issimilarly important. [12] Kirchner and co-workers [13] and our group [14] described aM n-complex-catalyzed multicomponent synthesis of pyrimidines from up to three different alcohols and amidines, ar eaction originally developed by our group with Ir catalysts. Milstein and co-workers showed very recently that aC o complex efficiently catalyzes the synthesis of pyrroles from diols and amines, [11] ar eaction originally introduced by the Crabtree group with aR uc atalyst (Scheme 1, top).…”