Carboazidation of alkenes and alkynes holds the promise to construct valuable molecules directly from chemical feedstock therefore is significantly important. Although a few examples have been developed, there are still some unsolved problems and lack of universal methods for carboazidation of both alkenes and alkynes. Here we describe an iron-catalyzed rapid carboazidation of alkenes and alkynes, enabled by the oxidative radical relay precursor t-butyl perbenzoate. This strategy enjoys success with a broad scope of alkenes under mild conditions, and it can also work with aryl alkynes which are challenging substrates for carboazidation. A large number of diverse structures, including many kinds of amino acid precursors, fluoroalkylated vinyl azides, other specific organoazides, and 2H-azirines can be easily produced.
A direct route to the synthesis of biologically active ellipticine quinones, olivacine, and calothrixin B is described. The prominent key steps involved are Friedel-Crafts hydroxyalkylation followed by oxidation and directed ortho-lithiation reactions of readily available indole-2-carboxylate esters with appropriately substituted pyridine and quinoline carboxaldehydes.
Bioactive indolo[3,2-j]phenanthridine alkaloids Calothrixin A and B have been synthesized by exploiting Pd-catalyzed cross-coupling reaction via C-H activation as a key step starting from 4-methoxycarbazole.
New pyrimido[4,5-b]carbazolone derivatives have been synthesized through cascade Ullmann N-arylation and aerobic oxidative C-H amidation reactions catalyzed by CuBr under air and ligand-free conditions.
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