Tieqiao Chen

Facile regio- and stereoselective hydrometalation of alkynes with a combination of carboxylic acids and group 10 transition metal complexes: selective hydrogenation of alkynes with formic acid.

A facile, highly stereo- and regioselective hydrometalation of alkynes generating alkenylmetal complex is disclosed for the first time from a reaction of alkyne, carboxylic acid, and a zerovalent group 10 transition metal complex M(PEt(3))(4) (M = Ni, Pd, Pt). A mechanistic study showed that the hydrometalation does not proceed via the reaction of alkyne with a hydridometal generated by the protonation of a carboxylic acid with Pt(PEt(3))(4), but proceeds via a reaction of an alkyne coordinate metal complex with the acid. This finding clarifies the long proposed reaction mechanism that operates via the generation of an alkenylpalladium intermediate and subsequent transformation of this complex in a variety of reactions catalyzed by a combination of Brϕnsted acid and Pd(0) complex. This finding also leads to the disclosure of an unprecedented reduction of alkynes with formic acid that can selectively produce cis-, trans-alkenes and alkanes by slightly tuning the conditions.

C–P Bond-Forming Reactions via C–O/P–H Cross-Coupling Catalyzed by Nickel

The first Ni-catalyzed C-O/P-H cross-coupling producing organophosphorus compounds is disclosed. This method features wide generality in regard to both C-O and P-H compounds: for C-O compounds, the readily available alcohol derivatives of aryl, alkenyl, benzyl, and allyl are applicable, and for P-H compounds, both >P(V)(O)H compounds (secondary phosphine oxide, H-phosphinate, and H-phosphonate) and hydrogen phosphines (>P(III)H) can be used as the substrates. Thus, a variety of valuable C(sp(2))-P and C(sp(3))-P compounds can be readily obtained in good to excellent yields by this new strategy.

Copper-Catalyzed Aerobic Oxidative Amination of sp3C–H Bonds: Efficient Synthesis of 2-Hetarylquinazolin-4(3H)-ones

An efficient synthesis of 2-hetarylquinazolin-4(3H)-ones via copper-catalyzed direct aerobic oxidative amination of sp(3)C-H bonds has been developed. This tandem oxidation-amination-cyclization transformation represents a straightforward protocol to prepare 2-hetaryl-substituted quinazolinones from easily available 2-aminobenzamides and (2-azaaryl)methanes.

Efficient Pd-Catalyzed Dehydrogenative Coupling of P(O)H with RSH: A Precise Construction of P(O)–S Bonds

A Pd-catalyzed dehydrogenative phosphorylation of thiols is developed. A variety of thiols dehydrogenatively couple readily with all three kinds of P(O)-H compounds, i.e., H-phosphonates, H-phosphinates, and secondary phosphine oxides, providing a general access to the valuable phosphorothioates including the P-chiral compounds. A plausible mechanism is proposed.

Nickel-Catalyzed Phosphorylation of Phenol Derivatives via C–O/P–H Cross-Coupling

An efficient nickel-catalyzed phosphorylation of phenol derivatives with P(O)-H compounds via C-O/P-H cross-coupling is described. Under the reaction conditions, various phenyl pivalates coupled readily with hydrogen phosphoryl compounds to afford the corresponding coupling products aryl phosphonates and aryl phosphine oxides in good to high yields.

Copper‐Catalyzed Aerobic Oxidative Inert CC and CN Bond Cleavage: A New Strategy for the Synthesis of Tertiary Amides

A copper-catalyzed aerobic oxidative amidation reaction of inert C-C bonds with tertiary amines has been developed for the synthesis of tertiary amides, which are significant units in many natural products, pharmaceuticals, and fine chemicals. This method combines C-C bond activation, C-N bond cleavage, and C-H bond oxygenation in a one-pot protocol, using molecular oxygen as the sole oxidant without any additional ligands.

Iron-catalyzed aerobic oxidative functionalization of sp3 C–H bonds: a versatile strategy for the construction of N-heterocycles

Iron-catalyzed aerobic oxidative functionalization of sp3 C–H bonds has been developed for the construction of N-heterocycles from easily available carboxylic acid derivatives and o-substituted anilines. This transformation represents a widely applicable protocol to N-heterocycles using biofriendly iron as a catalyst in combination with molecular oxygen or air as the sole oxidant.

Efficient nickel-catalyzed phosphinylation of C–S bonds forming C–P bonds

The first nickel-catalyzed phosphinylation of C-S bonds forming C-P bonds is developed. This transformation can proceed readily with the simple Ni(cod)2 at a loading down to 0.1 mol% at the 10 mmol scale. A variety of aryl sulfur compounds, i.e. sulfides, sulfoxides and sulfones all couple with P(O)-H compounds to produce the corresponding organophosphorus compounds in high yields, which provides an efficient new method for the construction of C-P bonds.

Chloroform-based Atherton–Todd-type reactions of alcohols and thiols with secondary phosphine oxides generating phosphinothioates and phosphinates

Chloroform-based Atherton–Todd-type reactions of alcohols and thiols with secondary phosphine oxides, generating phosphinothioates and phosphinates, respectively, are described. Various valuable phosphinothioates and phosphinates including those with functional groups are readily prepared under mild reaction conditions.

Nickel-catalyzed direct C-H/C-O cross couplings generating fluorobenzenes and heteroarenes.

The Ni-catalyzed direct C-H/C-O cross couplings of benzylic alcohol derivatives with fluorobenzenes and heteroarenes are disclosed. This transformation provides a straightforward and efficient method for the synthesis of these valuable heteroatom-containing compounds.