Tandem Rh-Catalyzed [4 + 2] Vinylic C–H <i>O</i>‑Annulation of Exocyclic Enones with Alkynes and 1,5‑H Shift

Active pyrylium intermediates are in situ generated by a Rh-catalyzed vinylic C–H annulation reaction between exocyclic α,β-enones and alkynes, which undergo a base-promoted rearrangement via 1,5-H shift to form 1<i>H</i>-benzo­[<i>f</i>]­chromene derivatives

Room-Temperature Coupling/Decarboxylation Reaction of α‑Oxocarboxylates with α‑Bromoketones: Solvent-Controlled Regioselectivity for 1,2- and 1,3-Diketones

A transition-metal-free and room-temperature coupling/decarboxylation reaction between α-oxocarboxylates and α-bromoketones is reported herein. It represents the first mild and regioselective synthesis of either 1,2- or 1,3-diketones from the same starting materials. Notably, the regioselectivity is simply controlled by solvents. The preliminary experimental data and DFT calculations suggest sequential Darzens-type coupling, alkaline hydrolysis, KOH-promoted oxirane opening and decarboxylation in one pot. This method is efficient for the synthesis of α,β-epoxy-γ-butyrolactone and curcuminoids

Cascade C–H Annulation of Aldoximes with Alkynes Using O₂ as the Sole Oxidant: One-Pot Access to Multisubstituted Protoberberine Skeletons

A cascade double C–H annulation of aldoximes with alkynes to produce benz­[<i>a</i>]­acridizinium salts is developed by using a simple catalytic system of [Cp*Rh­(OAc)₂]₂ in the presence of Zn­(OTf)₂ with oxygen as the sole oxidant. In addition, the challenging C–H annulation of aldoximes with alkynes, especially arylalkynes, to synthesize 1<i>H</i>-isoquinolines is also achieved under slightly modified conditions. This protocol provides an efficient one-pot access to multisubstituted dehydroberberinium skeletons from simple starting materials, which can be easily transformed into berberinium and tetrahydroberberine skeletons by controlled hydrogenation

Cascade C–H Annulation of Aldoximes with Alkynes Using O₂ as the Sole Oxidant: One-Pot Access to Multisubstituted Protoberberine Skeletons

A cascade double C–H annulation of aldoximes with alkynes to produce benz­[<i>a</i>]­acridizinium salts is developed by using a simple catalytic system of [Cp*Rh­(OAc)₂]₂ in the presence of Zn­(OTf)₂ with oxygen as the sole oxidant. In addition, the challenging C–H annulation of aldoximes with alkynes, especially arylalkynes, to synthesize 1<i>H</i>-isoquinolines is also achieved under slightly modified conditions. This protocol provides an efficient one-pot access to multisubstituted dehydroberberinium skeletons from simple starting materials, which can be easily transformed into berberinium and tetrahydroberberine skeletons by controlled hydrogenation

Novel Ruthenium Sensitizers with a Phenothiazine Conjugated Bipyridyl Ligand for High-Efficiency Dye-Sensitized Solar Cells

Two efficient ruthenium sensitizers with a phenothiazine-modified bipyridine as an ancillary ligand, coded <b>SCZ-1</b> and <b>SCZ-2</b>, have been developed as dyes in dye-sensitized solar cells (DSSCs). Both sensitizers exhibit low-energy metal-to-ligand charge transfer (MLCT) bands centered at 539 nm with high molar extinction coefficients of 1.77 × 10⁴ M^–1 cm^–1 for <b>SCZ-1</b> and 1.66 × 10⁴ M^–1 cm^–1 for <b>SCZ-2</b>, which are significantly higher than the corresponding value for the reference <b>N719</b> (1.27 × 10⁴ M^–1 cm^–1), indicating that the light-harvesting capacity of ruthenium sensitizers can be reinforced by introducing phenothiazine moieties into the bipyridine ligand. Under AM 1.5G irradiation (100 mW cm^–2), <b>SCZ</b>-<b>1</b> and <b>SCZ-2</b> sensitized DSSC devices show impressive power conversion efficiencies (PCE) up to 10.4% by using of iodide-based electrolytes, which exceeds that of <b>N719</b> (9.9%) under the same conditions. Both of the open circuit voltage (<i>V</i>_OC) and fill factor (FF) of <b>SCZ</b>-sensitized solar cells approximate to those of <b>N719</b>-sensitized cell. The relatively higher efficiencies of the <b>SCZ</b>-sensitized cells than that of <b>N719</b>-sensitized cell come from their higher short-circuit photocurrent density (<i>J</i>_SC), which may be mainly attributed to the high absorption coefficient. The absorption spectrum and device efficiency of <b>SCZ-1</b> are both quite close to those of <b>SCZ-2</b>, suggesting that the difference in alkyl chains on the N atom of phenothiazine is not a decisive factor in affecting the photovoltaic performance of dyes

Room-Temperature Coupling/Decarboxylation Reaction of α‑Oxocarboxylates with α‑Bromoketones: Solvent-Controlled Regioselectivity for 1,2- and 1,3-Diketones

A transition-metal-free and room-temperature coupling/decarboxylation reaction between α-oxocarboxylates and α-bromoketones is reported herein. It represents the first mild and regioselective synthesis of either 1,2- or 1,3-diketones from the same starting materials. Notably, the regioselectivity is simply controlled by solvents. The preliminary experimental data and DFT calculations suggest sequential Darzens-type coupling, alkaline hydrolysis, KOH-promoted oxirane opening and decarboxylation in one pot. This method is efficient for the synthesis of α,β-epoxy-γ-butyrolactone and curcuminoids