Yi-Feng Wang

Rhodium(III)-Catalyzed Synthesis of Isoquinolines from Aryl Ketone O-Acyloxime Derivatives and Internal Alkynes

A synthetic method of isoquinolines from aryl ketone O-acyloxime derivatives and internal alkynes has been developed using [Cp*RhCl(2)](2)-NaOAc as the potential catalyst system. The present transformation is carried out by a redox-neutral sequence of C-H vinylation via ortho-rhodation and C-N bond formation of the putative vinyl rhodium intermediate on the oxime nitrogen, where the N-O bond of oxime derivatives could work as an internal oxidant to maintain the catalytic cycle.

Mn(III)-mediated reactions of cyclopropanols with vinyl azides: synthesis of pyridine and 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives.

A Mn(III)-mediated divergent synthesis of substituted pyridines and 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives was exploited using readily available vinyl azides and cyclopropanols with a wide range of substituents. In short, the reactions of vinyl azides with monocyclic cyclopropanol provided pyridines in the presence of Mn(acac)(3) (1.7 equiv), whereas those with bicyclic cyclopropanols led to the formation of 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives using a catalytic amount of Mn(acac)(3). These reactions may be initiated by a radical addition of beta-keto radicals, generated by the one-electron oxidation of cyclopropanols, to vinyl azides to give iminyl radicals, which would cyclize with the intramolecular carbonyl groups. In addition, versatile transformations of 2-azabicyclo[3.3.1]non-2-en-1-ol to 2-azabicyclo[3.3.1]nonane or -non-2-nen frameworks were developed.

Copper-Mediated Aerobic Synthesis of 3-Azabicyclo[3.1.0]hex-2-enes and 4-Carbonylpyrroles from N-Allyl/Propargyl Enamine Carboxylates

Synthetic methods for 3-azabicyclo[3.1.0]hex-2-enes and 4-carbonylpyrroles have been developed that use copper-mediated/catalyzed reactions of N-allyl/propargyl enamine carboxylates under an O(2) atmosphere and involve intramolecular cyclopropanation and carbooxygenation, respectively. These methodologies take advantage of orthogonal modes of chemical reactivity of readily available N-allyl/propargyl enamine carboxylates; the complementary pathways can be accessed by slight modification of the reaction conditions.

Mn(III)-Mediated Formal [3+3]-Annulation of Vinyl Azides and Cyclopropanols: A Divergent Synthesis of Azaheterocycles

Mn(III)-mediated formal [3+3]-annulation has been developed using readily available vinyl azides and cyclopropanols with a wide range of substituents. Vinyl azides were successfully applied as a three-atom unit including one nitrogen to prepare pyridines and δ-lactams by the reactions with monocyclic cyclopropanols as well as to construct 2-azabicyclo[3.3.1] and 2-azabicyclo[4.3.1] frameworks with bicyclic cyclopropanols, bicyclo[3.1.0]hexan-1-ols, and bicyclo[4.1.0]heptan-1-ols. These reactions were initiated by a radical addition of β-carbonyl radicals, generated by the one-electron oxidation of cyclopropanols with Mn(III), to vinyl azides to give iminyl radicals, which cyclized with the intramolecular carbonyl groups. In addition, application of the present methodology to a synthesis of the quaternary indole alkaloid, melinonine-E, was accomplished.

Copper-catalyzed aerobic [3+2]-annulation of N-alkenyl amidines.

A method for the synthesis of bi- and tricyclic amidines has been developed through copper-catalyzed aerobic [3+2]-annulation reaction of N-alkenyl amidines. These cyclic amidines could be converted into mono-benzyl-protected vicinal diamines by the reduction with aluminum hydride.

Mn(III)-Catalyzed Synthesis of Pyrroles from Vinyl Azides and 1,3-Dicarbonyl Compounds

Polysubstituted N-H pyrroles with a wide variety of substituents were prepared from vinyl azides and 1,3-dicarbonyl compounds by using Mn(III) complexes as catalysts.

A Pd(II)-Catalyzed Ring-Expansion Reaction of Cyclic 2-Azidoalcohol Derivatives: Synthesis of Azaheterocycles

A Pd(II)-catalyzed ring expansion-reaction of cyclic 2-azidoalcohol derivatives was found to proceed via an unprecedented C-C bond cleavage-C-N bond formation sequence, providing substituted azaheterocycles.

TEMPO-Mediated Aliphatic C–H Oxidation with Oximes and Hydrazones

A method for aliphatic C-H bond oxidation of oximes and hydrazones mediated by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) has been developed, which enables the concise assembly of substituted isoxazole and pyrazole skeletons.

PhI(OAc)2‐Mediated Radical Trifluoromethylation of Vinyl Azides with Me3SiCF3

The fluorine-containing organic motif is becoming privileged in pharmaceuticals, agrochemicals, and functional materials, owing to its unique properties such as electron-withdrawing character, metabolic stability, and lipophilicity. Described herein is the PhI(OAc)2 -mediated radical trifluoromethylation of vinyl azides with Me3 SiCF3 to efficiently generate α-trifluoromethyl azines. The resulting α-trifluoromethyl azines were successfully transformed to valuable fluorine-containing molecules such as α-trifluoromethyl ketones, β-trifluoromethyl amines, 5-fluoropyrazoles, and trifluoroethyl isoquinolines.

Copper-Catalyzed Aliphatic C–H Amination with an Amidine Moiety

A method for amination of aliphatic C-H bonds of N-alkylamidines is described that utilizes Cu(OAc)(2) as the catalyst in the presence of PhI(OAc)(2) and K(3)PO(4). The resulting products, dihydroimidazoles and tetrahydropyrimidines, could be converted into the corresponding diamines by hydride reduction.