Huoji Chen

Palladium-Catalyzed Diacetoxylation of Alkenes with Molecular Oxygen as Sole Oxidant

A new palladium-catalyzed diacetoxylation of alkenes using oxygen as the sole oxidant to afford diacetates was developed. High levels of diastereoselectivity in diacetoxylation of 1,2-disubstituted alkenes was obtained.

Metal-Free Synthesis of 2-Aminobenzothiazoles via Aerobic Oxidative Cyclization/Dehydrogenation of Cyclohexanones and Thioureas

A metal-free process for the synthesis of 2-aminobenzothiazoles from cyclohexanones and thioureas has been developed using catalytic iodine and molecular oxygen as the oxidant under mild conditions. Various 2-aminobenzothiazoles, 2-aminonaphtho[2,1-d]thiazoles, and 2-aminonaphtho[1,2-d]thiazoles were prepared via this method in satisfactory yields.

Facile Synthesis of (E)-Alkenyl Aldehydes from Allyl Arenes or Alkenes via Pd(II)-Catalyzed Direct Oxygenation of Allylic C−H Bond

Palladium-catalyzed oxygenation of allyl arenes or alkenes has been developed to produce (E)-alkenyl aldehydes with high yields. Allylic C-H bond cleavages occur under the mild conditions during this process. Mechanistic studies show that oxygen source is water.

Copper-catalyzed aerobic oxidative transformation of ketone-derived N-tosyl hydrazones: an entry to alkynes.

A novel strategy involving Cu-catalyzed oxidative transformation of ketone-derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal alkynes and symmetrical diynes. Cross-coupling reactions of hydrazones with halides and terminal alkynes were performed to afford functionalized alkynes and unsymmetrical conjugated diynes. A mechanism proceeding through a Cu-carbene intermediate is proposed for the Cuf8ffC triple bond formation.

Highly efficient and practical synthesis of functionalized 1,5-dienes via Pd(II)-catalyzed halohomoallylation of alkynes

A Pd-catalyzed coupling of alkynes with homoallyl alcohols in ionic liquids has been reported, providing a practical, efficient, and versatile method for the synthesis of functionalized (1E)- or (1Z)-1,5-dienes in moderate to good yields. This reaction represents a rare instance of direct homoallylation of homoallyl alcohols.

Palladium‐Catalyzed Enyne Cyclization of 2′‐Alkenyl 2‐Alkynoates in Imidazolium‐Type Ionic Liquids

Abstract The use of [bmim][BF4], [bmim][PF6], and [bmim][Cl] ILs as the solvents in Pd(II)‐catalyzed enyne cyclization of 2′‐alkenyl 2‐alkynoates in the presence of cupric chloride has been investigated. The Z/E stereoselectivity of the reaction could range from 90:10 to 4:96 by tuning the amount of LiCl in ILs. After the separation of the product, the IL–catalyst mixture could be recovered by treatment with hydrochloric acid and recycled several times without an obvious loss of catalytic activity.