Manganese‐Catalyzed Dehydrogenative [4+2] Annulation of NH Imines and Alkynes by CH/NH Activation

Abstract

Described herein is a manganese-catalyzed dehydrogenative [4+2] annulation of NH imines and alkynes, a reaction providing highly atom-economical access to diverse isoquinolines. This transformation represents the first example of manganese-catalyzed CH activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition-metal-catalyzed CH activation. Mechanistic studies revealed the five-membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle.

Manganese‐Catalyzed Synthesis of cis‐β‐Amino Acid Esters through Organometallic CH Activation of Ketimines

“…[5][6][7] As a consequence, only sporadic examples of organometallic C À H activation reactions with inexpensive manganese catalysts have been described, with pioneering reports by the groups of Kuninobu and Takai, [8] as well as elegant recent contributions from Wang and co-workers. [9] Within our program on sustainable C À H functionalization processes, [10] we have developed a novel manganese-catalyzed direct synthesis of b-amino acid derivatives from easily available imines by organometallic CÀH activation. Notable features of our approach include an excellent functional-group tolerance, an unprecedented manganese-catalyzed CÀH activation/ alkene annulation process as well as a versatile cascade transformation with unusual cis diastereoselectivity.…”

Trapping oxygen in hierarchically porous carbon nano-nets: graphitic nitrogen dopants boost the electrocatalytic activity

“…7). The g-N- MM-Cnet air electrode showed an open circuit voltage of around 1.28 V, a current density of 560 mA cm À2 and a peak power of 324 mW cm À2 at 0.624 V. Both the current density at 1 V and peak power density were signicantly improved over previous reports on Zn-air batteries made of noble-metal-free electrodes (Table S6 †), 16,18,19 or Pt/C air cathodes with the same catalyst loading here (Fig. 7b).…”

“…6,7,[14][15][16][17] In order to elevate the activity and stability of N-doped carbon electrocatalysts for cheap, rechargeable and durable two-electrode metal-air batteries, the chemical structures of nitrogen heteroatoms and pore dimensions should be rationally designed to simultaneously optimize the activity and mass/charge transfer efficiency of nanocarbons for both ORR and OER. [18][19][20][21] There have been a number of long-term studies on controlling both the content and structure of nitrogen dopants in carbon based nanomaterials to boost their catalytic activity, not limited to ORR and OER performance. [22][23][24][25] For the nitrogen heteroatoms in the carbon framework based on their location (Table S2 †), pyridinic and pyrrolic N usually occurs at the domain edge.…”

Theoretical studies of palladium-catalyzed cycloaddition of alkynyl aryl ethers and alkynes

“…During the last three decades, many successful applications of catalytic C-H functionalization reactions directed toward the construction of C-C or C-N bonds have been reported in synthetic communities. Many transition metals, such as manganese [6], iron [7], cobalt [8], nickel [9], ruthenium [10], rhodium [11,12], palladium [9,[13][14][15][16][17], iridium [18], and platinum [19] have been found to catalyze C-H functionalization reactions.…”