Formation of the Tertiary Sulfonamide C(sp3)-N Bond Using Alkyl Boronic Ester via Intramolecular and Intermolecular Copper-Catalyzed Oxidative Cross-Coupling

A synthetic strategy for the formation of C(sp³)-N bonds, particularly through a copper-catalyzed oxidative cross-coupling, is rare. Herein, we report a novel synthetic approach for the preparation of tertiary sulfonamides via copper-catalyzed intra- and intermolecular oxidative C(sp³)-N cross-coupling reactions. This method allows the utilization of the readily available C(sp³)-based pinacol boronate as a substrate and the tolerance of a wide range of functional groups under mild reaction conditions. The success of this strategy relies on the unprecedented additive effects of silanol and NaIO₄.

Synthesis of substituted anilines via a gold-catalyzed three-component reaction

A three-component reaction for the synthesis of substituted anilines by a gold(i)-catalyzed domino reaction was developed.

Highly efficient Ru(ii)–alkylidene based Hoveyda–Grubbs catalysts for ring-closing metathesis reactions

Three novel phosphine-free Ru-alkylidenes (7a–7c) have been synthesized and utilized as efficient catalysts for ring closing metathesis (RCM) reaction. Spectroscopic data, i.e. NMR and HRMS, along with single crystal X-ray diffraction analysis, were used to confirm their chemical structures. The tosylated carbenoid 7b showed the highest efficiency in cyclizing different acyclic diene substrates. RCM of various (un)substituted N,N-diallylaniline derivatives and stereoselective RCM of different macromolecular dienes were well tolerated using only a catalytic amount (0.5–2.0 mol%) of the additive catalyst (7b) as compared to the well-known Grubbs (II) and Hoveyda–Grubbs (II) catalysts.

Three novel phosphine-free Ru-alkylidenes (7a–7c) have been synthesized and utilized as efficient catalysts for ring closing metathesis (RCM) reaction.

Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes

An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.

Tandem Organocatalytic Cycloaromatization/Intramolecular Friedel-Crafts Alkylation Sequence for the Synthesis of Indolizinones and Pyrrolo-azepinone Derivatives

The organocatalytic synthesis of indolizinones and pyrrolo-azepinones has been accomplished in a tandem fashion through a sequence that comprises initial cycloaromatization followed by intramolecular Friedel-Crafts alkylation. The process takes place under Brønsted acid catalysis, giving rise to final products in moderate to good yields. Attempts to carry out the tandem protocol in an enantioselective fashion were performed with chiral (R)-BINOL-derived N-triflyl phosphoramides. After initial optimization, the tandem process took place with moderate levels of enantioselectivity.

Ruthenium-Catalyzed Intramolecular Double Hydroalkoxylation of Internal Alkynes

Intramolecular double hydroalkoxylation of internal alkynes could be achieved using a Grubbs-type ruthenium carbene complex or its modified species to deliver a series of bridged- and spiroacetal derivatives in moderate to good yields. This study represents a new example of nonmetathetic reactions catalyzed by Grubbs-type ruthenium carbene complexes.

Intramolecular cooperativity in frustrated Lewis pairs

The doubly Lewis-acid functionalised aniline PhN[(CH₂)₃B(C₆F₅)₂]₂ features two competing boron functions in fast exchange for binding to the central Lewis base. In contrast to the mono acid-functionalised PhMeN[(CH₂)₃B(C₆F₅)₂], it is an active frustrated Lewis pair.

Synthesis of substituted styrenes and 3-vinylphenols using ruthenium-catalyzed ring-closing enyne metathesis

The synthesis of substituted styrenes 3 and 3-vinylphenols 9 was achieved by ring-closing enyne metathesis (RCEM)/dehydration of 7 and RCEM/tautomerization of 8, respectively. Those methods provide selective access to unique aromatic compounds and solve the problem of regioisomer formation.