The Synthesis of 5, 6, 7, 7a-Tetrahydro-1-methyl-3H-pyrrolizin-3-one by the Palladium-Catalyzed Cyclization of N-Bromoacetyl-2-vinylpyrrolidine

N-Bromoacetyl-2-vinylpyrrolidine underwent cyclization to give a pyrrolizidine derivative in the presence of a base and a catalytic amount of palladium catalyst.     

A novel N–O ligand for palladium-catalyzed Mizoroki–Heck reaction in neat water

1-(Morpholin-1-yl-pyridin-2-yl-methyl)-2-naphthol as a novel efficient N–O ligand has been developed for palladium-catalyzed Mizoroki–Heck reaction in neat water without the protection of an inert atmosphere. The reactions proceed smoothly and give the desired products in moderate to excellent yields. The catalyst system is reusable.     

Total Synthesis of (±)-Zearalanone

Summary.  A new approach to the macrocyclic lactone zearalanone is described utilizing an alkenol and an arene trifluoromethanesulfonate as starting materials. The key step is a Pd(0)-catalyzed cross-coupling of the arene trifluoromethanesulfonate with a 9-alkyl-9-borabicyclo[3.3.1]nonane derived from the alkenol. The title compound is obtained by macrolactonization of a hydroxy acid under Mitsunobu conditions. Received December 29, 2000. Accepted February 5, 2001     

Palladium-catalyzed cycloisomerisation reaction of 1,6-enyne acetic esters to form five-membered nitrogenated heterocyclic conjugated trienes

A palladium-catalyzed cycloisomerisation reaction of 1,6-enyne acetic esters have been developed. This cyclization reaction shows excellent regioselectivity and good functional group tolerance to obtain five-membered nitrogenated heterocyclic conjugated trienes in moderate to excellent yields. The resulting conjugated trienes could be facilely converted to highly substituted benzenes through Diels-Alder reactions.     

Enamines: efficient nucleophiles for the palladium-catalyzed asymmetric allylic alkylation

Enamines were tested to be efficient nucleophiles for palladium-catalyzed asymmetric allylic alkylation, avoiding the use of unstablilized ketone enolates formed by strong bases. The influence of the chiral metallocene-based ligands upon this reaction was studied in detail. It was shown that planar chirality played an important role in enantioselectivities. Meanwhile, different kinds of enamines and allylic acetate to the reactions were also investigated. High catalytic activity and excellent enantioselectivity (up to 99% ee) were obtained with pyrrolidine enamines of both aliphatic and aromatic ketone.     

Palladium-catalyzed mono-γ-arylation of 7-methoxy-4-methylcoumarin

Herein, we report the selective mono-γ-arylation of 7-methoxy-4-methylcoumarin under palladium-catalyzed conditions. The Buchwald G3 pre-catalyst in conjunction with either the Xantphos or N-Xantphos ligand proves to be highly reactive, engaging aryl iodides, bromides, chlorides, and triflates to effect the desired transformation. A wide range of functionality is tolerated, including the ability to activate heteroaryl halides in the transformation. The initial scope of aryl halides and limitations of this methodology are presented.     

Palladium-catalyzed direct ortho-alkynylation of aryl acetamides with low catalyst loading

The palladium-catalyzed alkynylation of phenylacetic acid derivatives using 4-CF₃C₆F₄NH₂ as the auxiliary is described. The reaction efficiency can be greatly promoted by pyridine ligand, which enables the reaction to proceed at a catalyst loading as low as 1 mol%. Various functional groups are tolerated under the reaction conditions. The kinetic studies show that the rate of the reaction is first order in phenylacetamide and the Pd(OAc)₂ in combination of the pyridine ligand provides a highly robust and effective catalyst.     

Reactivity control in palladium-catalyzed reactions: a personal account

Several classes of palladium-catalyzed reactions are summarized as the author's personal account. These include allylic oxidation, diastereo- and enantio-controlled allylic substitution, transmetalation of organomercurials, stereoselective rearrangements, and development of new ligands for amination of aryl halides and for asymmetric Heck addition.     

A convenient, large-scale synthesis of 4′-carboxamido N-Boc-2′,6′-dimethyl-l-phenylalanines

A large-scale synthesis of a series of 4′-carboxamido N-Boc-2′,6′-dimethyl-l-phenylalanines is described. This method features mild reaction conditions and high chemical yields from commercially available N-Boc-2′,6′-dimethyl-l-tyrosine methyl ester.     

Palladium-catalyzed cyclizative carbonylation of azobenzenes toward 3H-Indazol-3-ones using formic acid as CO source

A palladium-catalyzed cyclizative carbonylation of azobenzenes has been developed to access 1-acyl 2-aryl 3H-indazol-3-ones in moderate to good yields with good functional compatibility. This procedure proceeded with the sequential ortho-C–H carbonylation and cyclization, where formic acid served as the CO source. The practicability of this transformation was further increased by the employment of facilely available azobenzenes derivatives as one-handled starting materials.