Acceptorless Dehydrogenative Coupling Using Ammonia: Direct Synthesis of N-Heteroaromatics from Diols Catalyzed by Ruthenium

Abstract

The synthesis of N-heteroaromatic compounds via an acceptorless dehydrogenative coupling process involving direct use of ammonia as the nitrogen source was explored. We report the synthesis of pyrazine derivatives from 1,2-diols and the synthesis of N-substituted pyrroles by a multicomponent dehydrogenative coupling of 1,4-diols and primary alcohols with ammonia. The acridine-based Ru-pincer complex 1 is an effective catalyst for these transformations, in which the acridine backbone is converted to an anionic dearomatized PNP-pincer ligand framework.

Borrowing Hydrogen and Acceptorless Dehydrogenative Coupling in the Multicomponent Synthesis of N‐Heterocycles: A Comparison between Base and Noble Metal Catalysis

“…In 2018, mixtures of 2,5-and 2,6-substituted pyrazines were synthesized from 1,2-diols using ammonia as nitrogen source promoted by the acridine-based ruthenium pincer complex Ru-10 (Scheme 22). [41] In a similar manner, pyrroles were formed as well.…”

Sustainable catalysis with fluxional acridine-based PNP pincer complexes

“…Our group showed in 2018 that the aromatic complex 1 is an effective catalyst for the dehydrogenative direct synthesis of Nheteroaromatics such as pyrroles and pyrazines from alcohols in two/three-component reaction systems using ammonia gas (Figure 17a). 66 Multicomponent systems to access heterocycles with H 2 liberation were known previously, but they required the use of amino alcohols or amines as substrates. [67][68][69][70] The use of ammonia, on the other hand, has a clear economic advantage.…”

“…17a). 66 Multicomponent systems to access heterocycles with H 2 liberation were known previously, but they required the use of amino alcohols or amines as substrates. [67][68][69][70] The use of ammonia, on the other hand, has a clear economic advantage.…”

Rapid Multialkylation of Aqueous Ammonia with Alcohols by Heterogeneous Iridium Catalyst under Simple Conditions

“…The N‐alkylation reaction possesses a high atomic utilization and does not produce toxic or wasteful by‐products (only H 2 O is outgrowth) [15–18] . Up to now, the intensive research interests focus on developing homogeneous catalysed systems for the synthesis of organic amines using ammonia or its solution, and transition‐metal homogeneous catalysis systems utilizing Ru, [19–24] Ir, [25–27] have been the most advanced strategy [14] . For example, Fujita et al.…”