Among base metals used for C−H activation reactions, chromium(III) is rather unexplored despite its natural abundance and low toxicity. We report herein chromium(III)catalyzed C(sp 2 )−H functionalization of an ortho-position of aromatic and α,β-unsaturated secondary amides using readily available AlMe 3 as a base and using bromoalkynes, allyl bromide, and 1,4-dihydro-1,4-epoxynaphthalene as electrophiles. This redoxneutral reaction taking place at 70−90 °C, requires as low as 1−2 mol % of CrCl 3 or Cr(acac) 3 as a catalyst without any added ligand, and tolerates functional groups such as aryl iodide, boronate, and thiophene groups. Stoichiometric and kinetics studies as well as kinetic isotope effects suggest that the catalytic cycle consists of a series of thermally stable but reactive intermediates bearing two molecules of the amide substrate on one chromium atom and also that one of these chromate(III) complexes takes part in the alkynylation, allylation, and naphthalenation reactions. The proposed mechanism accounts for the effective suppression of methyl group delivery from AlMe 3 for ortho-C−H methylation.

The phosphaketene Ph3GePCO is shown to react with the phosphide KP(tBu)2 to generate the anion [Ph3GePC(O)P(tBu)2]− 1. This species reacts with CH3I or ClGePh3 to give the dissymmetric diphospha‐ureas (tBu)2PC(O)P(GePh3)(CH3) 2 and (Ph3Ge)2PC(O)P(tBu)2 3 respectively. Sequential treatment of 2 with a base and CH3I affords a route to (tBu)2PC(O)P(CH3)2 5. These species are products of the first modular diphospha‐urea synthesis. The subsequent thermal and photochemical reactivity of these species was also probed and described.

Reactions of Ph3GePCO with KP(t-Bu)2 and Ph3SiCl, or direct reaction with Ph3SiP(t-Bu)2 provides the (Z)- and (E)-isomers of the phosphaalkene (t-Bu2)PC(OSiPh3)P(GePh3) 2, respectively.