The efficient and catalytic amination of unactivated alkenes with simple secondary alkyl amines is preferentially achieved. A sterically accessible, N,O-chelated cyclic ureate tantalum catalyst was prepared and characterized by X-ray crystallography. This optimized catalyst can be used for the hydroaminoalkylation of 1-octene with a variety of aryl and alkyl amines, but notably enhanced catalytic activity can be realized with challenging N-alkyl secondary amine substrates. This catalyst offers turnover frequencies of up to 60 h–1, affording full conversion at 5 mol% catalyst loading in approximately 20 min with these nucleophilic amines. Mechanistic investigations, including kinetic isotope effect (KIE) studies, reveal that catalytic turnover is limited by protonolysis of the intermediate 5-membered azametallacycle. A Hammett kinetic analysis shows that catalytic turnover is promoted by electron rich amine substrates that enable catalytic turnover. This more active catalyst is shown to be effective for late stage drug modification.

Diiminopyrrolide copper alkoxide complexes, LCuOR (OR(1)=N,N-dimethylamino ethoxide, OR(2)=2-pyridyl methoxide), are active for the polymerization of rac-lactide at ambient temperature in benzene to yield polymers with M(w)/M(n)=1.0-1.2. X-ray diffraction studies showed bridged dinuclear complexes in the solid state for both complexes. While LCuOR(1) provided only atactic polylactide, LCuOR(2) produced partially isotactic polylactide (P(m)=0.7). The difference in stereocontrol is attributed to a dinuclear active species for LCuOR(2) in contrast to a mononuclear species for LCuOR(1).

Reaction of N-R,N′-R′-2,5-diiminopyrroles (R = R′ = S-CH(Me)Ph; R = R′ = CH 2 Ph; R = S-CH(Me)Ph, R′ = H) with Cu(OMe) 2 in the presence of chelating alcohols, ROH (R1 = C 2 H 4 NMe 2 , R2 = C 2 H 4 Py, R3 = CH 2 Py, R4 = CMe 2 Py) yielded the dinuclear, alkoxide-bridged complexes L 2 Cu 2 (OR) 2 . The complexes catalyze the polymerization of rac-lactide at room temperature with catalyst concentrations of 1−3 mM in 4−24 h (v = k[cat][monomer] with k = [2.3(5)] × 10 2 − [6.5( 6)] × 10 2 M −1 h −1 ). EPR and mechanistic studies indicate that the complexes remain dinuclear during the polymerization reaction. In complexes with OR1, both alkoxides of the dimer initiate polymerization, with OR2 or OR3 only one alkoxide initiates polymerization, and OR4 is inactive in polymerization. The nature of the bridging ligand in the dinuclear complex determines stereocontrol. Independent of the spectator ligand L, complexes which retain an OR3 or OR4 bridging ligand in the active species show preference for isotactic polymerizations (P m = 0.60−0.75), while those with only polymeryloxo bridges or OR2 as the bridging ligand provide atactic polymer. Stereocontrol follows a chain-end control mechanism, with the catalytic site likely adapting to the configuration of the chain end.