No abstract

The reactivity of allenes in transition-metal-catalyzed C-H activation chemistry is governed by the formation of either alkenyl-metal (M-alkenyl) or metal-π-allyl intermediates. Although either protonation or a β-hydride elimination is feasible with a M-alkenyl intermediate, cyclization has remained unexplored to date. Furthermore, due to the increased steric hindrance, the regioselectivity for the intramolecular cyclization of the metal-π-allyl intermediate was hampered towards the more substituted side. To address these issues, a unified approach to synthesize a diverse array of biologically and pharmaceutically relevant heterocyclic moieties by cobalt-catalyzed directed C-H functionalization was envisioned. Upon successful implementation, the present strategy led to the regioselective formation of dihydroisoquinolin-1(2H)-ones, isoquinolin-1(2H)-ones, dihydropyridones, and pyridones.

A friendly couple: Conditions have been uncovered that allow the desulfinylative CC cross‐coupling reaction of inexpensive sulfonyl chlorides and Grignard reagents (see scheme, acac=acetylacetonate, NMP=N‐methylpyrrolidone). The reactions rely on environmentally friendly iron catalysts and do not require expensive and/or toxic ligands.

FeCl 2 catalyzes the oxidative C-C cross-coupling of tertiary amines with terminal alkynes into propargylamines using (t-BuO) 2 as oxidant. The reaction can be applied to aromatic and aliphatic amines and alkynes without solvent. High chemoselectivity for aminomethyl groups is due to a steric factor.

In the presence of iron(II) chloride (FeCl 2 ; 20 mol%) and potassium tert-butoxide (tBuOK; 4 equiv.) in dimethyl sulfoxide (DMSO), aryl and heteroaryl iodides undergo stereoselective Mizoroki-Heck C À C cross-coupling reactions with styrenes at 60 8C giving the corresponding (E)-alkenes. The best yields are obtained upon adding a ligand (80 mol%) such as proline or picolinic acid. Aryl bromides and pyridinyl bromides are also coupled with styrenes but in lower yields.