DBU-mediated metal-free oxidative cyanation of α-amino carbonyl compounds: using molecular oxygen as the oxidant

Abstract

A novel DBU-mediated oxidative cyanation of α-amino carbonyl compounds by using air as the sole oxidant was developed under mild metal-free conditions for the first time. The reaction involves a tandem oxidation/Strecker reaction/oxidation process and provides a new and efficient method for the construction of α-iminonitriles in good to high yields in a single step.

Synthesis of β-Carbonyl α-Iminoamides by Double Insertion of Isocyanides into Aldehydes

“…The direct cyclization of product 3a with o-phenylenediamine gave quinoxaline 6 19 in 90% yield in the presence of NaOAc in HOAc. 20 Similarly, when oaminophenol was employed, benzo[d]oxazole 7 could be afforded in 82% yield from product 3a. 17e The amide moiety could be further transformed to 1H-tetrazole moiety (8, 70% yield) through a cycloaddition reaction by treatment with diphenylphosphoryl azide (DPPA).…”

“…The synthetic potential was demonstrated by the subsequent derivatization of product 3a , as illustrated in Scheme . The direct cyclization of product 3a with o -phenylenediamine gave quinoxaline 6 in 90% yield in the presence of NaOAc in HOAc . Similarly, when o -aminophenol was employed, benzo­[ d ]­oxazole 7 could be afforded in 82% yield from product 3a .…”

Silver-Assisted Oxidative Isocyanide Insertion of Ethers: A Direct Approach to β-Carbonyl α-Iminonitriles

“…α-Iminonitriles are important intermediates for the synthesis of functional compounds such as N -alkyl ketene–imines, cyanoenamides, amidines, and nitrogen-containing heterocycles, which are normally required multisteps to these moieties. The β-carbonyl α-iminonitriles, bearing an additional carbonyl group compared with α-iminonitriles, may demonstrate a rich array of chemistry . Previous methods for their synthesis have been barely reported, mainly concentrated on using prefunctionalized substrates, such as α-amino carbonyl compounds , or β-carbonyl nitriles, as the starting materials and required the utility of toxic sodium cyanide or trimethylsilyl cyanide (Scheme ).…”