Triflic Acid Catalyzed Oxidative Lactonization and Diacetoxylation of Alkenes Using Peroxyacids as Oxidants

A clean and efficient diacetoxylation reaction of alkenes catalyzed by triflic acid using commercially available peroxyacids as the oxidants has been developed. This method was also applied in oxidative lactonizations of unsaturated carboxylic acids in good to high yields

Aerobic Acetoxyhydroxylation of Alkenes Co-catalyzed by Organic Nitrite and Palladium

An aerobic acetoxyhydroxylation of alkenes cooperatively catalyzed by organic nitrite and palladium at room temperature using clean and cheap air as the sole oxidant has been developed. Various vicinal diols, diacetoxyalkanes, and dihalogenoalkanes have been synthesized. The gram-scale synthesis has also been approached. Vicinal difluorination and dichlorolation products have also been achieved via this reaction

Organopromoted Selectivity-Switchable Synthesis of Polyketones

In this work, an organopromoted metal-free pharmaceutical-oriented selectivity-switchable benzylic oxidation was developed, affording mono-, di-, and trioxygenation products, respectively, using oxygen as the oxidant under mild conditions. This process facilitates dioxygenation of 2,6-benzylic positions of heterocycles, which could be inhibited by heterocycle chelation to the metal cocatalysts. Enantiopure chiral ketones could also be prepared. The noninvolvement of transition metals and toxins avoids metal or hazardous residues, consequently ensuring a final-stage gram-scale synthesis of Lenperone

Direct Wittig Olefination of Alcohols

A base-promoted transition metal-free approach to substituted alkenes using alcohols under aerobic conditions using air as the inexpensive and clean oxidant is described. Aldehydes are relatively difficult to handle compared to corresponding alcohols due to their volatility and penchant to polymerize and autoxidize. Wittig ylides are easily oxidized to aldehydes and consequently form homo-olefination products. By the strategy of simultaneously in situ generation of ylides and aldehydes, for the first time, alcohols are directly transferred to olefins with no need of prepreparation of either aldehydes or ylides. Thus, the di/monocontrollable olefination of diols is accomplished. This synthetically practical method has been applied in the gram-scale synthesis of pharmaceuticals, such as DMU-212 and resveratrol from alcohols

Transition-Metal-Free Hydrogenation of Aryl Halides: From Alcohol to Aldehyde

A transition-metal- and catalyst-free hydrogenation of aryl halides, promoted by bases with either aldehydes or alcohols, is described. One equivalent of benzaldehyde affords an equal yield as that of 0.5 equiv of benzyl alcohol. The kinetic study reveals that the initial rate of PhCHO is much faster than that of BnOH, in the ratio of nearly 4:1. The radical trapping experiments indicate the radical nature of this reaction. Based on the kinetic study, trapping and KIE experiments, and control experiments, a tentative mechanism is proposed. As a consequence, a wide range of (hetero)­aryl iodides and bromides were efficiently reduced to their corresponding (hetero)­arenes. Thus, for the first time, aldehydes are directly used as hydrogen source instead of other well-established alcohol–hydrogen sources

Synthesis of Highly Functionalized Indoles and Indolones via Selectivity-Switchable Olefinations

Highly functionalized indoles and indolones were prepared via selectivity-switchable mono- or diolefinations. The Julia olefination of the products followed by a Brønsted acid-prompted cyclization afforded indolones, whereas the indoles were obtained by a sequential Wittig olefination and electrocyclization. This method opens divergent access to highly functionalized nitrogen-containing bicyclic or tricyclic heterocycles

Transalkylation via C–N Bond Cleavage of Amines Catalyzed by Super Organophotoreductant CBZ6

The super organoreductant CBZ6-catalyzed tandem transalkylation–cyclization using amines as traceless radical donors and stabilizer is reported. The later-stage breaking of an N–C bond enables the transalkylation with a secondary amine as the leaving moiety. A wide range of tertiary amines were used as alkyl radical donors for the C1–C8 alkyls. This traceless stabilizer also enabled the transalkylation with methyl radical, which is normally not possible because of the instability of methyl radical

Direct Alkylation of Amines with Alcohols Catalyzed by Base

A base-catalyzed/promoted transition-metal-free direct alkylation of amines with alcohols has been developed, giving the desired amines in generally high yields from either aromatic or aliphatic alcohols. On the basis of the ¹H NMR and in situ IR (React-IR) monitoring experiments, isotope-labeling experiments, as well as control experiments, a novel “hemiaminal” model is proposed to understand the mechanism, which explains the formation of the “extra” aldehyde in the reaction

Pharmaceutical-Oriented Selective Synthesis of Mononitriles and Dinitriles Directly from Methyl(hetero)arenes: Access to Chiral Nitriles and Citalopram

A pharmaceutical-oriented, transition-metal-free, cyanide-free one-step direct transformation of methylarenes to aryl nitriles is described. For the dimethylarenes, the selectivity can be well-controlled to form mononitriles or dinitriles. Enantioenriched nitriles can also be synthesized by this method. As a pharmaceutically practical method, the antidepressant drug citalopram was synthesized from cheap and commercially abundant <i>m</i>-xylene on a gram scale in high yield, avoiding transition-metal residues and toxic cyanides

Ru-Catalyzed Rearrangement of <i>N</i>‑Methyl Isoxazolidines to <i>N</i>–H 1,3‑Oxazinanes: A Strategy of Self-Hydride Transferring Cleavage of N–O Bonds

A strategy of ruthenium-catalyzed self-hydride transferring cleavage of N–O bonds was designed and utilized in a cascade 1,3-dipolar cyclization of alkenes and <i>N</i>-methyl nitrones followed by an <i>N</i>-demethylative rearrangement, furnishing synthetically useful <i>N</i>–H 1,3-oxazinanes