Palladium-Catalyzed Intramolecular Aminotrifluoromethoxylation of Alkenes

The first catalytic trifluoromethoxylation of unactivated alkenes has been developed, in which Pd­(CH₃CN)₂Cl₂ was used as catalyst, AgOCF₃ as trifluoromethoxide source, and Selectfluor-BF₄ as oxidant. A variety of 3-OCF₃ substituted piperidines were selectively obtained in good yields. Direct evidence was provided to address the facile reductive elimination of Pd^IV–OCF₃ complex to form sp³ C–OCF₃ bond

Palladium-Catalyzed Intramolecular Aminotrifluoromethoxylation of Alkenes

The first catalytic trifluoromethoxylation of unactivated alkenes has been developed, in which Pd­(CH₃CN)₂Cl₂ was used as catalyst, AgOCF₃ as trifluoromethoxide source, and Selectfluor-BF₄ as oxidant. A variety of 3-OCF₃ substituted piperidines were selectively obtained in good yields. Direct evidence was provided to address the facile reductive elimination of Pd^IV–OCF₃ complex to form sp³ C–OCF₃ bond

Pd-Catalyzed Intramolecular Aminohydroxylation of Alkenes with Hydrogen Peroxide as Oxidant and Water as Nucleophile

A palladium-catalyzed intramolecular aminohydroxylation of alkenes was developed, in which H₂O₂ was applied as the sole oxidant. A variety of related alkyl alcohols could be successfully obtained with good yields and excellent diastereoselectivities, which directly derived from oxidation cleavage of alkyl C-Pd bond by H₂O₂. Facile transformation of these products provided a powerful tool toward the synthesis of 2-amino-1,3-diols and 3-ol amino acids. Preliminary mechanistic studies revealed that major nucleophilic attack of water (S_N2 type) at high-valent Pd center contributes to the final C-O­(H) bond formation

Pd(II)-Catalyzed Aminofluorination of Alkenes in Total Synthesis 6‑(<i>R</i>)‑Fluoro­swainsonine and 5‑(<i>R</i>)‑Fluoro­febrifugine

The total syntheses of two fluorinated alkaloids, 6-(<i>R</i>)-fluoro­swainsonine and 5-(<i>R</i>)-fluoro­febrifugine, are described. Both encompass (4a<i>S</i>,7<i>R</i>,8a<i>R</i>)-7-fluoro-5-tosylhexa­hydro-4<i>H</i>-[1,3]­dioxino­[5,4-<i>b</i>]­pyridine as a key synthon which is obtained through a further optimized palladium-catalyzed aminofluorination of alkenes with high diastereoselectivity. 6-(<i>R</i>)-Fluoroswainsonine is synthesized from the key synthon in 14 steps, and 5-(<i>R</i>)-fluorofebrifugine requires a sequential 15-step transformation

Palladium-Catalyzed Intramolecular Aminoacetoxylation of Unactivated Alkenes with Hydrogen Peroxide as Oxidant

A palladium-catalyzed intramolecular aminoacetoxylation of unactivated alkenes was developed in which H₂O₂ was used as the sole oxidant. A variety of 3-acetoxylated piperidines were obtained in good yields with good to excellent regio- and diastereoselectivities. Mechanistic study revealed that the addition of di­(2-pyridyl) ketone (dpk) ligand was crucial to promote the oxidative cleavage of the C–Pd­(II) bond by H₂O₂ to give the C–OAc bond

Palladium-Catalyzed C–C Triple Bond Cleavage: Efficient Synthesis of 4<i>H</i>‑Benzo[<i>d</i>][1,3]oxazin-4-ones

Described herein is a new transformation of azidoalkynes by using a palladium catalyst, which involves a tandem process of aminopalladation of the alkyne and oxidative rearrangement. The reaction affords a variety of 4<i>H</i>-benzo­[<i>d</i>]­[1,3]­oxazin-4-ones. Mechanism studies support a Pd-catalyzed aminopalladation/oxidation/Baeyer–Villiger fragmentary sequence

One-Pot Synthesis of 1‑(Trifluoromethyl)-4-fluoro-1,2-dihydroisoquinolines and 4,4-Difluoro-1,2,3,4-tetrahydroisoquinolines

A cascade approach to 1-(trifluoromethyl)-4-fluoro-1,2-dihydroisoquinolines and 4,4-difluorotetrahydroisoquinolines has been developed. The procedure involves a silver-catalyzed intramolecular aminofluorination of alkyne. This one-pot reaction provides an efficient way to synthesize various fluorinated isoquinolines

Palladium-Catalyzed Intermolecular Azidocarbonylation of Alkenes via a Cooperative Strategy

A novel intermolecular β-azidocarbonylation reaction of alkenes has been developed in which a combination of iodine­(III)-mediated alkene activation and palladium-catalyzed carbonylation was demonstrated as an efficient strategy for the difunctionalization of alkenes. A variety of β-azido carboxylic esters were obtained from mono- and 1,1-disubstituted terminal alkenes with excellent regioselectivities. In addition, the introduced azido group can be reduced to an amine group, providing a facile access to β-amino acid derivatives from simple olefins

Copper-Catalyzed Intermolecular Trifluoromethylthiocyanation of Alkenes: Convenient Access to CF₃‑Containing Alkyl Thiocyanates

A highly selective and efficient approach for the direct trifluoromethylthiocyanation of alkenes has been developed using trimethylsilyl isothiocyanate (TMSNCS) as the thiocyanating agent and Togni reagent as the CF₃ source in the presence of copper­(I) catalyst. Both activated and unactivated alkenes work well to deliver various CF₃-containing thiocyanates

Palladium-Catalyzed Intermolecular Aminocarbonylation of Alkenes: Efficient Access of β‑Amino Acid Derivatives

A novel palladium-catalyzed intermolecular aminocarbonylation of alkenes has been developed in which the employment of hypervalent iodine reagent can accelerate the intermolecular aminopalladation, which thus provides the successful catalytic transformation. The current transformation presents one of the most convenient methods to generate β-amino acid derivatives from simple alkenes