Iminyl radical-triggered relay annulation for the construction of bridged aza-tetracycles bearing four contiguous stereogenic centers

Abstract

Bridged tetracyclic nitrogen scaffolds are found in numerous biologically active molecules and medicinally relevant structures. Traditional methods usually require tedious reaction steps, and/or the use of structurally specific starting materials....

Relay C–H Functionalization Enables De Novo Synthesis of Pyridines and Pyridones

“…Besides 1,5-HAT, the iminyl radical can occur formal 1,3-HAT to yield an α-carbon radical, which has been demonstrated by the synthesis of β-ketophosphonates and some N-heterocycles (Scheme c) . Stimulated by these results, and the aim to further increase atom utilization of the iminyl radical, as well as our ongoing interests in radical relay annulations, , we wish to challenge a relay C–H functionalization task to accomplish annulation reactions. As shown in Scheme d, an iminyl radical proceeds formal 1,3-HAT to deliver an α-carbon radical that subsequently adds into an alkene to form a carbon radical.…”

Urea Synthesis from Isocyanides and O-Benzoyl Hydroxylamines Catalyzed by a Copper Salt

“…In addition, we recently reported Ag- and Cu-catalyzed difunctionalization of the isocyano group, involving isocyanide insertion into the N-O bond, for the rapid generation of pyrimidinediones [ 19 ] and dihydroquinolinones [ 20 ], respectively ( Scheme 3 b,c). Based on these studies and our continuous interest in N-O bond transformations [ 21 , 22 , 23 ], we wished to develop more methods regarding isocyanide insertion into N-O bonds for the synthesis of N-containing compounds. Herein, we describe a Cu-catalyzed method for the rapid assembly of ureas using aryl isocyanides and O-benzoyl hydroxylamines as readily accessible starting materials ( Scheme 3 d).…”