Xian-Rong Song

Electrophile-driven regioselective synthesis of functionalized quinolines.

Highly substituted 3-iodoquinolines bearing different alkyl and aryl moieties can be synthesized in moderate to excellent yields (up to 99%) by 6-endo-dig iodocyclization of 2-tosylaminophenylprop-1-yn-3-ols with molecular iodine (I(2)) under mild conditions. The cyclization is highly regioselective and the resulting 3-iodoquinolines can be further functionalized by various coupling reactions.

Recent Developments in the Trifluoromethylation of Alkynes

In the last few years, the development of versatile methodologies to incorporate trifluoromethyl groups into organic molecules has attracted significant attention in synthetic chemistry. This review gives an overview over the development on the trifluoromethylation of alkynes, which have not been solely discussed before. Formation of diverse C(sp, sp(2) , sp(3) )-CF3 bonds are all covered in this review.

Palladium(II)-Catalyzed Tandem Cyclization/C–H Functionalization of Alkynes for the Synthesis of Functionalized Indoles

A palladium-catalyzed tandem cyclization/C-H functionalization of two alkynes was accomplished to construct a series of polycyclic functionalized indoles. A range of internal alkynes bearing synthetically useful functional groups were tolerated. A good regioselectivity was observed when alkyl-substituted alkynes were introduced into the reaction system, and a single product was obtained. Molecular oxygen was used as the terminal oxidant in the approach, rendering the reaction more sustainable.

Copper-catalyzed trifluoromethylation-cyclization of enynes: highly regioselective construction of trifluoromethylated carbocycles and heterocycles.

Regioselective trifluoromethylation-cyclization: A method for copper-catalyzed trifluoromethylation-cyclization of simple enynes using the CC triple bond as a nucleophile is reported for the first time. The reaction proceeds efficiently in a highly regioselective manner to give various 5- or 6-exo-dig carbocycles and heterocycles in moderate to high yields.

Copper-Catalyzed Oxidative Cyclization of Enynes for the Synthesis of 4-Carbonyl-quinolines with O2

A novel copper-catalyzed oxidative cyclization of enynes and in situ formed enynes leading to 4-carbonyl-quinolines by using dioxygen as an oxygen source has been developed.

Facile Synthesis of Disubstituted Isoxazoles from Homopropargylic Alcohol via C═N Bond Formation

A novel iron-catalyzed aerobic oxidative reaction to synthesize disubstituted isoxazoles from homopropargylic alcohol, t-BuONO, and H2O is developed. The method provides mild conditions to afford a variety of useful substituted heterocycles in an efficient and regioselective manner. The mechanism has been studied and proposed, which indicates that the transformation can be realized through construction of a C═N bond and C═O bond, C-H oxidation, and then cyclization. Moreover, this method can be enlarged to gram scale.

Palladium‐Catalyzed CH Activation and Intermolecular Annulation with Allenes

A new and efficient Pd(II) -catalyzed intermolecular annulation of N-benzoylsulfonamide with allenes for the synthesis of 3,4-dihydroisoquinolin-1(2H)-ones is reported. This CH functionalization is compatible with ambient air and moisture, and it can be applied to terminal or internal allenes with different synthetically attractive functional groups. Control experiments and a kinetic isotope effect study are conducted and a plausible mechanism is proposed.

Gold-catalyzed cascade reaction of hydroxy enynes for the synthesis of oxanorbornenes and naphthalene derivatives.

An efficient and selective gold-catalyzed cascade reaction for the synthesis of oxanorbornenes and naphthalene derivatives from easily prepared hydroxy enynes has been developed. Divergent products could be obtained from the same substrates by different gold catalytic systems.

TMSCl-Mediated Synthesis of α,β-Unsaturated Amides via C–C Bond Cleavage and C–N Bond Formation of Propargyl Alcohols with Trimethylsilyl Azide

A new method with high efficiency for the synthesis of α,β-unsaturated amides from the easily prepared propargyl alcohols and TMSN3 using TMSCl as an acid promoter is developed. A wide variety of α,β-unsaturated amides were produced in moderate to excellent yields. Mechanistic studies indicate that this transformation involves TMSCl-mediated allenylazide intermediate formation, C-C bond cleavage, and C-N bond formation. Significantly, this reaction shows good functional group compatibility and high regioselectivity, with a relatively short reaction time and inexpensive reagents.

Regioselective access to CF3S-substituted dihydrofurans from homopropargylic alcohols with trifluoromethanesulfenamide

A facile access to 4-((trifluoromethyl)thio)-2,3-dihydrofurans from unprotected homopropargylic alcohols in high regioselectivity is reported. This method is the first example of using a free hydroxy group as a nucleophile to complete a trifluoromethylthiolation/cyclization protocol with an alkyne in moderate to excellent yields.