Palladium-Catalyzed Tandem Cyclization/Suzuki Coupling of 1,6-Enynes

A Pd(0)-catalyzed 1,6-enyne cyclization−arylation cascade reaction was effected via π-allylpalladium intermediate formation and subsequent Suzuki coupling to give cyclic products with stereodefined exocyclic double bonds

<i>cis</i>-Chloropalladation of 1,6-Enynes

A PdCl2-catalyzed cis-chloropalladation−cyclization reaction of various 1,6-enyne substrates was developed. This Pd-catalyzed enyne cyclization reaction represents a new route for the synthesis of stereodefined α-halomethylene-γ-butyrolactones, lactams, tetrahydrofurans, and cyclopentanes. A mechanism involving a neighboring coordination group is proposed to explain the experiment results

Fully Reagent-Controlled Asymmetric Synthesis of (−)-Spongidepsin via the Zr-Catalyzed Asymmetric Carboalumination of Alkenes (ZACA Reaction)

The ZACA reaction has been shown to proceed satisfactorily with internally OH-substituted 1-alkenes, provided that the OH group is unprotected and non-allylic. This reaction was used for reagent-controlled asymmetric construction of 3. Allylic alcohol was converted to 2 in seven steps via iterative ZACA processes and simple chromatography. (−)-Spongidepsin (1) was synthesized by using 2 and 3 through application of the esterification−amidation−ring-closing metathesis protocol previously reported

Palladium-Catalyzed Tandem Cyclization/Suzuki Coupling Reaction of 1,2,7-Trienes

A Pd(0)-catalyzed 1,2,7-triene cyclization/arylation cascade reaction was realized via π-allylpalladium intermediate formation and a subsequent Suzuki coupling reaction to preferentially give a five-membered ring product with a stereodefined exocyclic double bond. Excellent cis/trans selectivity was achieved (only cis-3 was isolated) with heteroatom-tethered 1,2,7-triene substrates

Divergent Synthesis of 2‑Aminofurans via Palladium-Catalyzed Acetoxylative, Alkoxylative, and Hydroxylative Cycloisomerization of Homoallenyl Amides

A fine-tunable transformation, including Pd-catalyzed acetoxylative, alkoxylative, and hydroxylative cycloisomerization of homoallenyl amides, has been realized with hypervalent iodine organic compounds as the oxidants, giving polysubstituted 2-aminofurans in promising yields at room temperature. The selective formation of three different types of products from the same starting materials makes this reaction particularly attractive and useful for organic synthesis

Divergent Synthesis of 2‑Aminofurans via Palladium-Catalyzed Acetoxylative, Alkoxylative, and Hydroxylative Cycloisomerization of Homoallenyl Amides

A fine-tunable transformation, including Pd-catalyzed acetoxylative, alkoxylative, and hydroxylative cycloisomerization of homoallenyl amides, has been realized with hypervalent iodine organic compounds as the oxidants, giving polysubstituted 2-aminofurans in promising yields at room temperature. The selective formation of three different types of products from the same starting materials makes this reaction particularly attractive and useful for organic synthesis

Copper-Catalyzed <i>trans</i>-Carbohalogenation of Terminal Alkynes with Functionalized Tertiary Alkyl Halides

A highly <i>trans</i>-selective Cu-catalyzed carbohalogenation including carbobromination, carboiodination, and carbochlorination of terminal alkynes with activated tertiary alkyl halides has been realized, providing quaternary-carbon-containing alkenyl halides in good yields with excellent regio- and stereoselectivity. Meanwhile, an unprecedented alkyne <i>trans</i>-carboalkynylation process has been achieved via the tandem <i>trans</i>-carbohalogenation/Sonogashira coupling reaction, which furnishes highly functionalized 1,3-enynes in a single chemical transformation

Palladium-Catalyzed Cycloisomerization and Aerobic Oxidative Cycloisomerization of Homoallenyl Amides: A Facile and Divergent Approach to 2‑Aminofurans

A Pd-catalyzed divergent cyclization, including cycloisomerization and aerobic oxidative cycloisomerization of homoallenyl amides, is described. Varieties of functionalized 2-amino-5-alkylfurans and 2-amino-5-formylfurans can be selectively synthesized in good to excellent yields. Preliminary mechanistic studies show that peroxide may be a key intermediate for this Pd-catalyzed radical aerobic oxidative cycloisomerization of homoallenyl amides. The mild reaction conditions, high atom economy, and utilization of air as the oxygen source make this protocol very environmentally benign and practical to the synthetic community

Divergent Synthesis of 2‑Aminofurans via Palladium-Catalyzed Acetoxylative, Alkoxylative, and Hydroxylative Cycloisomerization of Homoallenyl Amides

A fine-tunable transformation, including Pd-catalyzed acetoxylative, alkoxylative, and hydroxylative cycloisomerization of homoallenyl amides, has been realized with hypervalent iodine organic compounds as the oxidants, giving polysubstituted 2-aminofurans in promising yields at room temperature. The selective formation of three different types of products from the same starting materials makes this reaction particularly attractive and useful for organic synthesis

Efficient and Selective Synthesis of (<i>S</i>,<i>R</i>,<i>R</i>,<i>S</i>,<i>R</i>,<i>S</i>)-4,6,8,10,16,18-Hexamethyl- docosane via Zr-Catalyzed Asymmetric Carboalumination of Alkenes (ZACA Reaction)

(S,R,R,S,R,S)-4,6,8,10,16,18-Hexamethyldocosane (1) was synthesized in 11% yield in 11 steps in the longest linear sequence from ≥98% pure (S)-β-citronellal and 6 additional steps for the preparation of 11 in 23% yield from propene. Five of the six asymmetric carbon centers were generated catalytically and stereoselectively by the ZACA reaction (5 times), one lipase-catalyzed acetylation, and two chromatographic operations