The effect of the catalyst structure on the stereoselectivity of CO/vinyl arene copolymerization has been studied with the aim of developing catalytic systems able to improve the yields while maintaining the high degree of copolymer isotacticity previously obtained using achiral nitrogen ligands. Aryl α-diimine ligands having extended aromatic rings (Ar)2DABMe2, with Ar = 1-C10H7 (e), 1-C14H9 (f), 9-C14H9 (g), have been synthesized, and α-diimine coordination to cationic methylpalladium complexes has been investigated in solution, by means of NMR spectroscopy, and in the solid state for [Pd(Me)(NCMe)((9-C14H9) 2DABMe2)][PF6] (2g). The performance of these catalysts in CO/vinyl arene copolymerization, under mild conditions, was analyzed in terms of productivity and degree of stereoregularity of the resulting polyketones. In comparison with previous results, a remarkable enhancement in the yield of isotactic copolymer was observed using the new achiral 9-anthryl α-diimine ligand g, confirming that the ortho disubstitution and the extended aromatic rings play key roles in obtaining good stereoselectivity and good productivity. To perform a structural analysis of the first steps of the CO/p-methylstyrene copolymerization, complex [Pd(Me)(CO)((9-C14H9)2DABMe2)] [BAr′4] (3g) was used as a starting point: NMR investigation reveals the stereoselective formation of the olefin/CO/olefin insertion product (6g), which prevalently exists in solution in only one diastereoisomeric form, thus justifying the observed high polymer isotacticity

A simple and efficient organocatalytic enantioselective hydrophosphonylation of imines to enantiomerically enriched alpha-amino phosphonates is reported. By using 10 mol % of quinine as the catalyst in the enantioselective addition of diethyl phosphite to N-Boc protected imines, alpha-amino phosphonates are obtained in moderate to good yields and with up to 94% ee.

A general approach to the catalytic asymmetric aza‐Henry reaction has been developed. The combination of a commercially available phase‐transfer catalyst (PTC) with a base is able to promote the in situ formation of N‐carbamoyl imines from α‐amido sulfones and activate nitromethane towards the asymmetric addition reaction, thus furnishing N‐carbamoyl‐protected β‐nitroamines in good yields and with up to 98 % ee (see scheme; PG=protecting group).

Two pyrene‐tagged iminopyridines (NN′) were used to synthesize neutral and monocationic, palladium(II) complexes, [Pd(Me)Cl(NN′)] and [Pd(Me)(MeCN)(NN′)][PF6]. The monocationic complexes generated active catalysts in the CO/vinyl arene copolymerization, leading to polyketones with yields and molecular weight strongly dependent on N‐N′, with the ketimine catalysts one order of magnitude more productive than the aldimine counterpart. The stereochemistry of polyketones synthesized with the aldimine catalyst was found to be dependent on the vinyl comonomer: prevailingly syndiotactic copolymers were obtained for styrene, prevailingly isotactic copolymers were produced for 4‐methyl styrene, and atactic macromolecules were formed for 4‐tert‐butyl styrene. The statistical analysis demonstrated that the control of the stereochemistry switched from enantioselective site control for 4‐methyl styrene to a combination of chain‐end and enantioselective site control for styrene.

Diels or no Diels? A bifunctional organic catalyst based on the thiourea motif is able to coordinate both diene and dienophile in an unprecedented asymmetric Diels–Alder reaction of 3-vinylindole derivatives, giving a rapid access to optically active tetra- and hexahydrocarbazoles with excellent results in terms of yields, diastereoselectivities, and enantioselectivities