Pd-catalyzed Allylic Amination Research Articles

Novel strategies for the preparation of aminocarbasugar analogues: syntheses of N-substituted aminocyclitols from d-mannose

Two strategies, based on the Pd-catalyzed allylic amination and the epoxidation-nucleophilic opening, have been described for the preparation of aminocarbasugar analogues from an exo-methylene cyclohexane derivative readily accessible in five steps from d-mannose by 6- exo- dig-radical cyclization as the key transformation.

Highly regio- and enantioselective Pd-catalyzed allylic alkylation and amination of monosubstituted allylic acetates with novel ferrocene P,N-ligands.

Highly regio- and enantioselective Pd-catalyzed allylic alkylation and amination of monosubstituted allylic acetates with novel ferrocene P,N-ligands.

Palladium Complexes with Chiral Oxazoline Ligands. Effect of Chelate Size on Catalytic Allylic Substitutions

Mono- and bimetallic allylic palladium complexes (1L−5L) with L being chiral bidentate oxazoline ligands (from pyridine (a−d), quinoline (e−g), and piperazine (h)), containing different kinds of allyl groups (1−5), were easily obtained, and their structures in solution were elucidated by NMR spectroscopy. Complex 1d was also characterized by X-ray diffraction. The activity of these complexes in palladium-catalyzed allylic alkylation for acyclic and cyclic substrates was tested. For catalytic systems with ligands a−g, the activity was very high, although the enantioselectivity was low for pyridine derivatives and moderate for quinolino-oxazoline ligands, showing the beneficial effect of chelate size in the latter case. In contrast, the palladium tetraaza catalytic system (Pd/h) exhibited a low activity and a low asymmetric induction. Allylic complexes 1a, 1d, and 1e were also active in the Pd-catalyzed allylic amination, but the activity of these systems was lower than for the alkylations. Under in situ ca...

Recent studies in asymmetric catalysis using ferrocenyl ligands

Chiral bidentate ferrocenyl ligands have been fined-tuned in terms of their steric and electronic properties, and thus adapted to a variety of reactions catalyzed by transition metals. The position of the two ligating units (two different PR2 groups, two pyrazolyl, or a combi- nation thereof) attached to the ferrocenylethyl fragment may be interchanged. A comparison of P,N-ligands with their corresponding inversed (N,P) counterpart is presented for the Pd-catalyzed allylic amination. Dendrimers containing Josiphos-type ligands up to the third generation have been prepared and used in e.g. Rh-catalyzed hydrogenation reactions. The intramolecular Ir- catalyzed hydroamination reaction has been found to require an acidic N-H functionality and the presence of co-catalytic amounts of base. Olefin isomerization was found to be an important competing side-reaction. Kinetic/mechanistic studies of the Pd-catalyzed hydrosilylation of styrenes have been carried out.

Highly Efficient Synthesis of Cephalotaxine by Two Palladium‐Catalyzed Cyclizations

Interesting for cancer therapy: The unique pentacyclic alkaloid cephalotaxine is the parent compound of the strongly cytotoxic harringtonines, which are isolable from the study-east Asian yewtree. Now the cephalotaxine precursor 2 has been synthesized highly efficiently and selectively in two steps from the readily accessible amine 1 through an intramolecular Pd-catalyzed allylic amination to form the spirocycle (85% yield) and subsequent Heck reaction to construct the seven-membered ring (80% yield).