Using Methanol as a Formaldehyde Surrogate for Sustainable Synthesis of N‐Heterocycles via Manganese‐Catalyzed Dehydrogenative Cyclization

Abstract

The development of an efficient and sustainable synthetic route for formaldehyde production from renewable feedstock, especially in combination with a subsequent transformation to straightforwardly construct valuable chemicals, is highly desirable. Herein, we report a novel manganese-catalyzed dehydrogenative cyclization of methanol as a formaldehyde surrogate with a variety of dinucleophiles for facile synthesis of N-heterocycles. The in situ generated formaldehyde via catalytic methanol dehydrogenation can be selectively trapped by diverse dinucleophiles to avoid several possible side reactions. The utility of this transformation is further highlighted by its successful application to the synthesis of 13 C-labeled N-heterocycles using 13 CH3OH as a readily accessible 13 C-isotope reagent.

Manganese‐Catalyzed Asymmetric Formal Hydroamination of Allylic Alcohols: A Remarkable Macrocyclic Ligand Effect

“…Among them, Mn I ‐catalyzed asymmetric hydrogenation [10] and transfer hydrogenation [11] are much more attractive, and expected to acquire more eye‐catching achievements. Considering the wide applications of multidentate PNP, [9a–f, 10a–c, 11a,f] PNN, [9g–i, 10d–g, 11b] and NNN [9j–l] pincer ligands in manganese catalysis and based on the continuing efforts of our group in asymmetric hydrogenation, [12] we envisioned that the above designed chiral N 6 ‐macrocyclic ligands could be applied in Mn I ‐catalyzed asymmetric catalysis. To the best of our knowledge, there is no report on Mn I ‐catalyzed enantioselective reactions by utilizing a chiral peraza macrocyclic ligand so far.…”

Reactivity of [(PNP)Mn(CO)2] with Organophosphates

“…Complexes of ( i Pr PN H P)­Mn­(CO) 2 (X) derived from the hydration of 2 with electrophiles have shown little propensity for turnover without forcing conditions such as high temperatures (>100 °C) or the addition of strong bases. − Experiments into the reactivity and turnover of 2 with DIFP yielded mixed results. Complex 2 crystallizes with three molecules of water in the unit cell, so reactions can be expected to contain excess H 2 O.…”

“…Prior work using ( i Pr PNP)­Mn­(CO) 2 ( 1 , i Pr PNP = N­(CH 2 CH 2 ( i Pr2 P)) 2 ), a low-spin 16-electron manganese­(I) complex, has demonstrated wide utility, including ambiphilic reactivity. Catalytic reactions concerning the generation − or consumption − of H 2 using 1 have been well studied, and the ability to tailor the reactivity of 1 by altering reaction conditions is a valuable property. The electrophilic reactivity of 1 has been demonstrated with several element–hydrogen bonds, including carboxylic acid substrates that are isolobal and isoelectronic with OPA surrogate substrates .…”

Copper-Catalyzed Hydrogen Production through the Dehydrogenative Coupling of Methanol and Diamine

“…The main product in solution is vinyl urea, with a theoretical hydrogen storage capacity of up to 6.6 wt %. Despite the remarkable advantages of homogeneous catalysis systems in dehydrogenative coupling of methanol and diamines, most of them predominantly rely on precious noble-metal catalysts. , Additional limitations stem from the utilization of intricate or noncommercial organic ligands, the subpar stability of organometallic complexes, and the necessity for supplementary bases to activate the catalyst, all of which curtail their practical applicability.…”