Richard Gil

Kinetic resolution of 3-tbutyl and 3-phenyl cyclobutylidenethanols through lipase-catalyzed acylation with succinic anhydride.

Abstract Optically enriched (3-t-butyl) and (3-phenylcyclobutylidene)ethanols were readily obtained through kinetic resolution of the racemates by lipase-catalyzed acylation with succinic anhydride; the procedure is of practical use and does not require a chromatographic separation.

A convenient solvent-free preparation of 1,3,5-trioxanes

In the presence of a small amount of trimethylsilyl chloride, aldehydes gave at room temperature in solvent-free conditions the corresponding 1,3,5-trioxanes with good to excellent yields.

An Alternative Procedure in the Takai Reaction Using Chromium(III) Chloride Hexahydrate as a Convenient Source of Chromium(II)

Abstract An alternative procedure in the Takai reaction using chromium(III) chloride hexahydrate as the source of Cr(II) was performed. The use of zinc as Cr(III) reducer allowed us to carry out the iodovinylation of aldehydes in 63–99% yields. With the Garner and Dondoni aldehydes, these conditions along with a work-up using 4-t-butylpyridine allowed us to improve the yield of the corresponding vinyl iodide compared to the previous procedures.

On the molecular structure and geometry of pyridylalkylamine–H+ complexes: application to catalytic enantioselective hydroxyalkylation of indoles

The protonation of 2-pyridylalkylamines (PAA) was investigated through quantum chemical calculations at a DFT level of theory in dichloromethane solution. Two different PAA–H+ species and a dynamic equilibrium between protonated forms were evidenced. The overall geometry of the PAA–H+ promoters is strongly influenced by the nature of the moiety and the absolute configuration of the pseudobenzylic stereocenter. Thus, PAA–H+ complexes were used as organocatalysts in the enantioselective hydroxyalkylation of indole derivatives. The combination of PAA, a strong acid and a soft counter-ion was found to be a mandatory parameter to achieve high yields and selectivities allowing hydroxyalkylation of both N–H and N-protected indoles using a unique catalytic system.

Conjugate additions of alkylchromium reagents mediated by chromium(III) chloride/manganese

Abstract Benzyl and glycosylchromium reagents generated from the corresponding halides and the couple Cr(III)/Mn were added to activated alkenes to afford Michael adducts. The influence of a ligand around the chronium atom as well as the use of a catalytic amount of chromium chloride were investigated.

Asymmetric Assisted Tandem Catalysis: Hydroamination followed by Asymmetric Friedel–Crafts Reaction from a Single Chiral N,N,N′,N′‐Tetradentate Pyridylmethylamine‐Based Ligand

With the rising interest in asymmetric catalysis promoted by earth‐abundant elements, a chiral ligand will undoubtedly be the most valuable unit of the catalyst. The first proof of concept of the use of a multitask chiral ligand in an asymmetric assisted tandem catalysis protocol that successively combines metallo‐ and organocatalytic processes is reported herein. In this protocol, the chiral ligand of the newly designed rare‐earth catalyst of the first reaction is converted into a novel chiral organocatalyst for the second transformation by the simple addition of HCl. The observation of some enantioinduction in the tandem sequence—alkyne hydroamination followed by enantioselective Friedel–Crafts alkylation—confirms the relay of the chiral N,N,N′,N′‐tetradentate ligand and the importance of its pyridylmethylamine scaffold.

Charge-transfer complexes interactions evidenced by chemical force microscopy

Charge-transfer complexes have been detected by chemical force microscopy (CFM) between a tip and a substrate respectively functionalized with trinitrofluorenone and 9-anthracenemethanol siloxane derivatives.

First-Row Late Transition Metals for Catalytic Alkene Hydrofunctionalisation: Recent Advances in C-N, C-O and C-P Bond Formation

This review provides an outline of the most noteworthy achievements in the area of C-N, C-O and C-P bond formation by hydroamination, hydroalkoxylation, hydrophosphination, hydrophosphonylation or hydrophosphinylation reaction on unactivated alkenes (including 1,2- and 1,3-dienes) promoted by first-row late transition metal catalytic systems based on manganese, iron, cobalt, nickel, copper and zinc. The relevant literature from 2009 until mid-2017 has been covered.

Synthesis, characterisation and application of pyridine-modified chitosan derivatives for the first non-racemic Cu-catalysed Henry reaction

The preparation, characterisation and application of two pyridine-modified chitosan derivatives (C1 and C2) containing Cu(OAc)2 adsorbed as catalysts for the conversion of benzaldehyde into 2-nitro-1-phenylethanol are described. Quantitative solid-state 13C multiple-contact cross-polarization, magic-angle-spinning, nuclear magnetic resonance (MC-CP MAS NMR) measurements confirmed the successful grafting of 2-pyridinecarboxaldehyde and 6-methylpyridine-2-carboxaldehyde to the chitosan backbone and indicated that 47(±2)% of the NH2 groups were grafted for both C1 and C2. The use of C1-Cu(OAc)2 as a catalyst in the nitroaldol reaction led to 96(±1)% conversion and 19(±4)% enantiomeric excess (ee), while the use of C2-Cu(OAc)2 as a catalyst also promoted the nitroaldol reaction, affording almost quantitatively the expected 2-nitro-1-phenylethanol (98(±1)%) with 14.5(±1.5)% ee.