Catalytic Deprotection of Alkyne Dicobalt Hexacarbonyl Complexes using Near-Infrared Photocatalysis.

Dicobalt hexacarbonyl complexes are well-known for their applications in the Nicholas reaction or simply as a protecting group for alkynes. To recover the alkyne, demetalation is necessary, which usually involves a stoichiometric amount of an oxidizing agent or a strong ligand. This article reports a demetalation methodology based on a photocatalytic process.

Near-infrared photocatalysis with cyanines: synthesis, applications and perspectives.

Cyanines are organic dyes bearing two aza-heterocycles linked by a polymethine chain. Excited states, fluorescence, redox activity, and energy transfer are interesting properties of cyanines which have been used by chemists. Moreover, they are easily accessible and highly tunable.

3D-Printed Eosin Y-Based Heterogeneous Photocatalyst for Organic Reactions.

Heterogenization of Eosin Y by 3D-printing and its application in photocatalysis are reported. The approach allows a fine tuning of the photocatalyst morphology and its rapid preparation. Photocatalytic activity was evaluated through model organic reactions involving oxidation, reduction, and photosensitization pathways.

Second Generation of Near-Infrared Cyanine-Based Photocatalysts for Faster Organic Transformations.

A second generation of cyanine-based near-infrared photocatalysts has been developed to accelerate organic transformations. Cyanines were prepared and fully characterized prior to evaluation of their photocatalytic activities. Catalyst efficiency was determined by using two model oxidation and reduction reactions.

Selective Terminal Functionalization of Linear Alkanes.

A two-step sequential strategy involving a biocatalytic dehydrogenation/remote hydrofunctionalization, as a unified and versatile approach to selectively convert linear alkanes into a large array of valuable functionalized aliphatic derivatives is reported. The dehydrogenation is carried out by a mutant strain of a bacteria Rhodococcus and the produced alkenes are subsequently engaged in a remote functionalization through a metal-catalyzed hydrometalation/migration sequence that subsequently react with a large variety of electrophiles. The judicious implementation of this combined biocatalytic and organometallic approach enabled us to develop a high-yielding protocol to site-selectively functionalize unreactive primary C-H bonds.

Heterogeneous Photoredox Catalysis Based on Silica Mesoporous Material and Eosin Y: Impact of Material Support on Selectivity of Radical Cyclization.

Heterogenization of the photocatalyst appears to be a valuable solution to reach sustainable processes. Rapid and efficient synthesis of supported photocatalyst is still a remaining challenge and the choice of the support material is crucial. The present study aims at preparing a new generation of hybrid inorganic/organic photocatalysts based on silica mesoporous material and Eosin Y.

Synthetic study toward tridachiapyrone B.

A convergent approach to the skeleton of tridachiapyrone B is described taking advantage of the desymmetrization of α,α'-dimethoxy-γ-pyrone leading to α-crotyl-α'-methoxy-γ-pyrone in one step. To construct the quaternary carbon of the 2,5-cyclohexadienone of the target, a strategy based on the Robinson-type annulation of an aldehyde derived from α-crotyl-α'-methoxy-γ-pyrone was applied. The grafting of the simplified target's side chain was demonstrated through an oxidative anionic oxy-Cope rearrangement of the tertiary alcohol arising from the 1,2-addition of a 1,3-dimethylallyl reagent to 2,5-cyclohexadienone connected to the α'-methoxy-γ-pyrone motif.

Squaraines as near-infrared photocatalysts for organic reactions.

Herein, unprecedented uses of squaraine derivatives as new organic near-infrared photocatalysts are reported. These efficient molecular tools are able to promote oxidation and reduction for organic transformations through photocatalytic conditions. A mechanistic investigation is performed to distinguish between competitive Single Electron Transfer and Energy Transfer pathways.

Synthesis and [*C]CO-labelling of (C,N) -dimethylbenzylamine-palladium complexes for potential applications in positron emission tomography.

Various aryl-palladium complexes were synthesised from gem-dimethylbenzylamine derivatives by C-H activation under extremely mild conditions. Interestingly, these highly stable structures reacted with [13C]carbon monoxide to produce the desired labelled lactams in 29% to 51% yields over the C-H activation/carbonylation steps. As representative examples, a non-natural amino acid and an estradiol-based conjugate were prepared and labelled in model experiments with [13C]CO in homogeneous or heterogeneous conditions.

Cyanine-based near infra-red organic photoredox catalysis.

Direct metal-free near infra-red photoredox catalysis is applied to organic oxidation, photosensitization and reduction, involving cyanines as photocatalysts. This photocatalyst is competitive with conventional reactions catalyzed under visible light. Kinetic and quenching experiments are also reported.

Total Synthesis of C30 Botryococcene and epi-Botryococcene by a Diastereoselective Ring Opening of Alkenylcyclopropanes.

Trialkylaluminum compounds perform a diastereoselective 1,6-ring fragmentation of alkenylcyclopropane. This new tool allows the preparation of hydrocarbon compounds containing two distant stereocenters with a good diastereocontrol. Inspired by the biosynthesis of botryococcene this methodology was applied successfully to the diastereo- and enantioselective preparation of this triterpene and its epimer.

Domino Ring Expansion: Regioselective Access to 9-Membered Lactones with a Fused Indole Unit from 2-Nitrophenyl-1,3-cyclohexanediones.

The domino anionic fragmentation of 2-nitrophenyl-1,3-cyclohexanediones containing an electrophilic appendage such as aldehyde and epoxide is disclosed. This reaction, initiated by a series of nucleophiles, involves the generation of an intermediate hydroxylate followed by the regioselective formation and fragmentation of an intermediate lactolate into enolate. This strategy, devoid of any protecting group, enlarges the initial ring and provides an original access to decorated 9-membered lactones with a fused indole unit.

New one-pot approach towards gold nanorods and nanowires: a parametric study of gold halide/lithium tert-butoxide systems.

Various gold nanomaterials are successful obtained using a mild and simple chemical approach, involving the use of gold halide and lithium tert-butoxide in organic solvents. It was found that the presence of bromide ions in a polar solvent is required to produce faceted gold nanoparticles such as nanorods/nanowires. The parametric study of the system AuBr3 in presence of lithium tert-butoxide in THF points out that the ratio [gold salt]/[alkoxide] has a strong influence on the formation of nanorods/nanowires.