Guilong Li

Catalytic Asymmetric Addition of Alcohols to Imines: Enantioselective Preparation of Chiral N,O-Aminals

The enantioselective addition of alcohols to imine electrophiles has been shown to proceed in the presence of a catalytic amount of a chiral phosphoric acid catalyst. The reaction allows for the formation of the respective chiral N,O-aminals in excellent yield and enantioselectivity. A total of 11 different alcohols and 11 different imines were successfully used as a clear demonstration of the reaction generality.

Highly Enantioselective Hydrogenation of Enamides Catalyzed by Chiral Phosphoric Acids

A highly enantioselective hydrogenation of enamides catalyzed by a dual chiral-achiral acid system was developed. By employing a substoichiometric amount of a chiral phosphoric acid and acetic acid, catalyst loadings as low as 1 mol % of the chiral catalyst were sufficient to provide excellent yield and enantioselectivity of the reduction product.

An asymmetric Diels-Alder reaction catalyzed by chiral phosphate magnesium complexes: highly enantioselective synthesis of chiral spirooxindoles.

Mild Magic: A mild, enantioselective Diels-Alder reaction, catalyzed by a chiral magnesium phosphate species, has been developed for the synthesis of various chiral spirooxindoles. Molecular sieves were found to have a considerable effect when used as additives in this reaction.

Direct Synthesis of Chiral 1,2,3,4-Tetrahydropyrrolo[1,2-a]pyrazines via a Catalytic Asymmetric Intramolecular Aza-Friedel–Crafts Reaction

The direct asymmetric intramolecular aza-Friedel-Crafts reaction of N-aminoethylpyrroles with aldehydes catalyzed by a chiral phosphoric acid represents the first efficient method for the preparation of medicinally interesting chiral 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazines with high yields and high enantioselectivities. This strategy has been shown to be quite general toward various aldehydes and pyrrole derivatives.

Chiral Phosphoric Acid-Catalyzed Desymmetrization of meso-Aziridines with Functionalized Mercaptans

Conditions for the phosphoric acid-catalyzed highly enantioselective ring-opening of meso-aziridines with a series of functionalized aromatic thiol nucleophiles are described. The procedure utilizes commercially available aromatic thiols, a series of meso-aziridines, and a catalytic amount of VAPOL phosphoric acid to explore the substrate scope of this highly enantioselective reaction.

Chiral Magnesium BINOL Phosphate-Catalyzed Phosphination of Imines: Access to Enantioenriched α-Amino Phosphine Oxides

A new method to synthesize chiral α-amino phosphine oxides is reported. The reaction combines N-substituted imines and diphenylphosphine oxide and is catalyzed by a chiral magnesium phosphate salt. A wide variety of aliphatic and aromatic aldimines substituted by electron-neutral benzhydryl or dibenzocycloheptene groups were excellent substrates for the addition reaction. The dibenzocycloheptene protected imines afforded improved enantioselectivity in the resulting products. Substituted diphenylphosphine oxide nucleophiles also showed good reactivity.

Catalytic Asymmetric Aza-Darzens Reaction with a Vaulted Biphenanthrol Magnesium Phosphate Salt

Conditions for a catalytic asymmetric aza-Darzens aziridine synthesis mediated by a vaulted biphenanthrol (VAPOL) magnesium phosphate salt is described. Using simple substrates, this methodology explores the scope and reactivity of a new magnesium catalyst for an aziridination reaction capable of building chirality and complexity simultaneously.

Chiral phosphoric acid catalyzed addition of dihydropyrans to N-acyl imines: stereocontrolled access to enantioenriched spirocyclic oxazoletetrahydropyrans with three contiguous stereocenters.

Dihydropyran derivatives readily undergo addition to N-acyl imines in the presence of chiral phosphoric acids. This addition process yields an attractive product that is capable of a tandem oxidative-cyclization via an epoxide intermediate.