Synthesis of heterocycles via aerobic Ni-catalyzed imidoylation of aromatic 1,2-bis-nucleophiles with isocyanides

o-Phenylene N-substituted iminocarbonates have been obtained by aerobic Ni-catalyzed reaction of readily available catechols and isocyanides. The choice of oxidant and absence of base proved crucial to avoid competitive catechol oxidation into (semi)quinone, leading to degradation. The developed protocol is generally applicable on other oxidation-sensitive aromatic 1,2-bisnucleophiles, generating a variety of important bicyclic heterocycles from readily available building blocks, hitherto only accessible via aerobic noble metal catalysis. Experimental studies suggest involvement of a Ni (H) -catecholate complex, which has been supported by density functional theory of the catalytic cycle. o-Phenylene N-substituted iminocarbonates demonstrated to be interesting platform molecules providing access to dialkyl N-substituted iminocarbonates, dialkyl N-substituted dithioiminocarbonates, and N,N',N ''-trialkyl guanidines via reaction with respectively alcohols, thiols, and amines. The catechol, which is concomitantly produced as a byproduct in these substitution reactions, can be recycled. 'When 4-propylcatechol, accessible from pine and clove tree feedstock, is applied, the leaving group is also biorenewable.

Publication year:2022

Keywords:A1 Journal article

Accessibility:Open