Arnaud Martel

Université du Maine · Institut des Molécules et des Matériaux du Mans (IMMM)

The possible presence of plastic particles with a size smaller than 1 μm in the aquatic environment raises widespread concern over their environmental impact. Therefore, it is important to understand whether and to what extent nanoplastics dispersed in water degrade under UV irradiation. To address this issue, we studied the effect of UV irradiatio...

An improvement in the catalytic enantioselective allylboration of isatins with 2-allyl-1,3,2-dioxaborolane in the presence of chiral BINOL derivatives is reported, offering an efficient one-step access to enantioenriched N-unprotected 3-allyl-3-hydroxy-2-oxindoles. This catalytic process is also effective for the crotylboration reaction with enanti...

Saint‐Maurice Abbey in Carnoët (Finistère) underwent an in‐depth archaeological appraisal during 2018–2019, involving several non‐destructive technologies: the geophysical survey revealed the presence of expected structures, drawn on ancient plans, but also the presence of structures unknown up until now. A group of buildings on the edge of the pon...

Aldol addition of α-triisopropylsilyl-α-diazoacetone (TIPS-diazoacetone), promoted by excess lithium diisopropylamide (LDA), was developed and applied to the synthesis of original C-TIPS diazoaldols, C-TIPS diazoketols, and a related Mannich-type product. An unprecedented mechanistic pathway has been proposed, involving a lithiated triazene interme...

An efficient two‐step strategy for the synthesis of constrained C‐glycosyl amino acid derivatives from C‐vinylglycosides involving a 1,3‐dipolar cycloaddition using l‐(–)‐menthone‐derived nitrone as the key step is described. After optimization of 1,3‐dipolar cycloaddition conditions, various C‐vinylglycosides were tested leading exclusively to one...

3,4‐Dihydro‐2H‐pyrans are present in the skeletons of several natural products, and these versatile synthetic intermediates are readily transformed into tetrahydropyrans, pyridines, or 1,5‐dicarbonyl units. Among the strategies developed to access 3,4‐dihydro‐2H‐pyrans, the hetero‐Diels‐Alder reaction between an oxadiene and a dienophile is particu...

This review provides an overview on the applications of α-Halogenoacetamides in domino and cycloaddition reactions. α-Halogenoacetamides are versatile building blocks that can lead to a wide variety of complex aza-heterocycles of biological interest when engaged in domino and/or cycloaddition reactions. The reactivity and the reaction conditions in...

In this paper, a new access to several chiral 3-aminoglycals as potential precursors for glycosylated natural products is reported from a common starting material, (−)-methyl-L-lactate. The stereodivergent strategy is based on the implementation of a ring-closing metathesis of vinyl ethers as key step of reaction sequences developed.

A stereospecific Mizoroki‐Heck cross‐coupling of differently substituted glycals with haloarenes resulting in the exclusive formation of either alpha or beta aryl‐C‐glycosides depending solely on the configuration at C3 is reported. The reaction is easy to set up as no specific precaution are required concerning moisture as well as oxygen, and proc...

Highly diastereo- and enantioselective 1,3-dipolar cycloadditions between functional ketonitrones and β-substituted enals are promoted by organocatalysis with the imidazolidinium catalyst of MacMillan. Study of the scope of the reaction shows that high selectivities are conserved by varying the N-protecting group or the ester function. However it i...

The access to new oxazolo[3,2-d][1,4]oxazepin-5(3H)-ones starting from α-bromoamido alcohols and Michael acceptors under mild conditions is presented. This domino process proved to be chemo-, regio- and stereoselective and allows the formation of a large diversity of highly functional 7-membered rings in good yields up to 95%. The complete shift of...

The Robinson annulation is a reaction that has been useful for numerous syntheses since its discovery in 1935, especially in the field of the steroid synthesis. The products are usually obtained after 3 consecutive steps which are the formation of an enolate (or derivative), a conjugate addition and an aldol reaction. Over the years, several method...

The Robinson annulation is a reaction that has been useful for numerous syntheses since its discovery in 1935, especially in the field of the steroid synthesis. The products are usually obtained after 3 consecutive steps which are the formation of an enolate (or derivative), a conjugate addition and an aldol reaction. Over the years, several method...

An original and rapid domino reaction for access to oxazolidin-4-ones is presented. Simply by heating α-bromoamido alcohol in the presence of KNaCO3 and water with readily prepared Michael acceptors, an unprecedented molecular rearrangement is generated. This new methodology enables the hitherto unreported synthesis of functionalized oxazolidin-4-o...

The exploration of the composition space diagram of the FeF3/ZnF2-Hamtetraz-HFaq system (Hamtetraz = 5-aminotetrazole) by solvothermal synthesis at 160 °C for 72 h in dimethylformamide (DMF) has evidenced five new hybrid fluorides (1-5); the structures are characterized from single crystal X-ray diffraction data. [Hdma]·(ZnFeIII(H2O)4F6) (1) and [H...

A short and efficient synthesis of bicyclo[2.2.2]octane-1,4-dicarboxylic acid involving the formation of a semicarbazone is developed, and a reproducible protocol for the reduction of this semicarbazone is described. The use of microwaves significantly shortens the duration of the sequence to the diacid compared to the previously described syntheti...

Bicyclic isoxazolidines displaying one or two quaternary stereocenter(s) were formed starting from functional cyclic ketonitrones equipped with a phenyl glycinol chiral auxiliary. The products were engaged in stereocontrolled 1,3-dipolar cycloaddition reactions with a range of electron-rich and electron-poor dipolarophiles. A new reductive removal...

This paper describes the synthesis of both polysubstituted oxazolo-pyrrolidinones and -piperidinones by a domino process. The methodology is based on the reaction between hydroxyl halogenoamides and Michael acceptors, which leads efficiently to bicyclic lactams. The process is compatible with unsymmetrical electron-withdrawing groups on the Michael...

Enantiopure vinyl ethers of Stericol® underwent diastereoselective thermal 1,3 dipolar cycloadditions with N-benzyl, N-benzhydryl, and N-PMB aspartate ester nitrones. Chemoselective N-debenzylation of the resulting cycloadducts afforded diastereomerically and enantiomerically pure crystalline NH-isoxazolidine, the absolute configuration of which wa...

Original acyclic (E)-α,α-dialkylketonitrones bearing a chiral auxiliary on their nitrogen atom were synthesized and successfully employed for the asymmetric synthesis of α,α-disubstituted amino acids using regio- and stereocontrolled 1,3-dipolar cycloaddition reactions with vinyl ethers. N-Glycosyl chiral auxiliaries were found to provide excellent...

A catalytic 1,3-dipolar cycloaddition between carboalkoxy ketonitrones and methacrolein under the effect of chiral ruthenium Lewis acid (R,R-1) was developed with high regio-, diastereo- and enantiocontrol. The diastereochemical outcome of the cycloaddition reaction is marked by a significant solvent effect, and a divergent endo or exo control can...

Highly enantio- and exo-selective 1,3-dipolar cycloadditions of alanine-derived ketonitrones to E-crotonaldehyde could be realized in a good yield by the use of a chiral imidazolidinone salt without the addition of water. The origin of the stereoselectivity in the reaction was discussed and the absolute configuration of the cycloadduct determined u...

A review was given on the cycloaddn. of hetero-substituted alkenes bearing a S, halo, P, or Si atom, highlighting the modulation of both the reactivity of the dipolarophiles and the regioselectivity induced in the cycloaddn., depending on the oxidn. state of the heteroatom directly linked to the alkene in the case of S and P. The hetero substituent...

Eu(fod) 3-catalyzed heterocycloaddition of chiral β-alkyl-N-vinyl-1,3-oxazolidin-2-ones with a heterodiene bearing a lipidic chain led to heterocycloadducts in high yield with excellent endo and facial selectivities. An original lipidic lactone, a potent precursor of a ceramide analog, was obtained in seven steps from the adduct in a convergent man...

The [4+2] heterocycloaddition reaction between (E)-γ-substituted β-unsaturated α-oxo esters 1a−d and cyclic and acyclic ketone enol ethers 2a−l afforded heteroadducts 3−5 in high yields when either [Eu(fod)3] or SnCl4 were used as the catalyst. With methyl (E)-benzylidenepyruvate (1a), the two catalytic modes displayed divergent stereoselectivities...

Efficient access to masked β-amino-aldehydes was performed starting from 6-alcoxy tetrahydrooxazinone (I) (R1 = Ph, tert-Bu, Bn) (6-ATO). Transacetalization leads to the opening of the cycle to form either unsym. acetal (II) or sym. acetals, e.g. (III) (R1 = Ph, tert-Bu, Bn). These amino acetals are key compds., obtained with 99% ee, which can be e...

A totally new acid-free domino process to access highly functionalized bicyclic γ- and δ-lactams starting from commercially available and inexpensive ethoxymethylene derivatives is reported. Mechanisms elucidated by computational calculations led to new reaction conditions that boosted the yields up to 3.5 times higher.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Amino acid derived nitrones were conveniently synthesized in good-to-excellent yields by condensation of alpha-ketoesters with N-benzylhydroxylamine. The cycloaddition reactions of these nitrones with different alkenes were investigated under thermal solvent-free conditions. Considering conversions, yields, and selectivities, alkyl vinyl ethers hav...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

N-(beta,beta-Difluorovinyl)oxazolidin-2-ones were conveniently prepared in good yields in two steps from the parent oxazolidin-2-ones. The [3+2]- and [4+2]-cycloaddition-type reactions with electron-deficient partners were investigated as first application of these new enamides. TMSOTf was efficient in promoting these two reactions, and the corresp...

A high-yielding, practical 2-step procedure for the prepn. of PhCH2NHOH starting from (PhCH2)2NH is described. As specified in the detailed protocol, the reaction can be conveniently carried out on a > 0.5 mol lab. scale. [on SciFinder(R)]

Chiral enamides, easily prepared in one step from a cyclic ketone and an oxazolidinone, are successfully employed in high-yielding, endo, and facially selective Hetero-Diels - Alder reactions involving activated oxadienes and Siever’s reagent as catalyst. From the resulting bicyclic heteroadducts, a novel and efficient asymmetric modification for the...

New ionic-liquid-supported tin reagents were synthesized and used in Stille cross-coupling reactions. High yields of biaryls were obtained under low-temperature, solvent-free, ligand-free conditions, with simple purification techniques. Moreover, the tin compound could be recycled up to five times without significant loss of reactivity. An expanded...

The first de novo synthesis of a beta-C-naphthyl glycoside displaying a convenient functionality for subsequent transformations into complex C-aryl glycosides is reported. The synthesis of this (+/-)-beta-C-1,5-dibenzyloxynaphthyl 6,6,6-trifluoro-3-amino glycoside relies on a hyperbaric HDA reaction involving a new 2-vinylnaphthalenic dienophile.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

C-Naphthyl glycosides displaying a 1,5-difunctionality on the naphthalene ring that can undergo oxidn. to bromo-naphthoquinone are key intermediates in the synthesis of natural C-aryl glycoside analogs. In this area, sugar-modified derivs. are of specific interest, but their synthesis is challenging. The de novo access to such compds. has been inve...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

New isoxazolidines were synthesized in good to excellent yields by 1,3-dipolar cycloaddition of N-vinylamide dipolarophiles and nitrones. Strikingly, solvent-free conditions gave high conversion and yields, shortened reaction time, and minimized degradation products. N-Vinyloxazolidin-2-one and its analogues used in these cycloaddition reactions we...

N-benzyl aspartate nitrones 2, prepared by addition of N-benzylhydroxylamine to dialkyl acetylenedicarboxylates 1, underwent [3 + 2] thermal cycloaddition with a wide range of alkenes to afford isoxazolidines 4 bearing a polyfunctionalized quaternary center. Under these uncatalyzed conditions, the trans stereocontrol observed with vinyl ethers is h...

A new practical approach to enantioenriched carboxy-differentiated aspartate derivs. was achieved in three steps via the 1,3-dipolar cycloaddn. of nitrone deriv. PhCH2N(:O):CHCO2Et with (R)-4-ethyl-N-vinyloxazolidin-2-one, and chemoselective nucleophilic displacement of the resulting aspartimide I under appropriate conditions (racemization less tha...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Trimethylsilyl trifluoromethanesulfonate (TMSOTf) was conveniently used to promote the reaction involving N-alkenyloxazolidin-2-ones and activated nitrones, leading to new 4-substituted 5-azaisoxazolidines in good to excellent yields. This TMSOTf-promoted procedure expanded the scope of reaction of N-vinyloxazolidin-2-ones and nitrones in complemen...

Two new bisflavan-3-ols, named colletinin A (1) and 2,2´´-diepicolletinin A (2) have been isolated from Rhododendron collettianum. Their structures were determined by means of 1D and 2D NMR analysis, aided by HREIMS data. The relative configuration was determined by means of 1 H- 1 H NOESY correlation but the absolute configuration could not be es...

N-Vinyl-1,3-oxazolidin-2-ones, -1,3-oxazolidine-2-thiones, and -N'-methylimidazolidin-2-one were conveniently used as new dipolarophiles in thermal 1,3-dipolar cycloaddn. involving activated nitrones, and led to new 5-N-substituted isoxazolidines in high yields. A moderate to total trans-diastereoselectivity was obsd., increasing with the degree of...

The development of an approach to the synthesis of 3-oxo-7-hydroxy-9-decanolides, e.g. (±)-decarestrictine J (I), of biol. interest. is described. This strategy involves two key steps: the inverse electron demand Hetero-Diels-Alder reaction of an original dienophile (1,5-dimethoxv-cyclohexa-1,4-diene), which will ensure the construction of an advan...

For Abstract see ChemInform Abstract in Full Text.

A convergent synthetic pathway for access to the functionalized (±)-9-decanolides is described, using a [4+2] bicyclic heterocycloadduct as the key intermediate. Thus, the exo adduct I led to hemiacetal II via a 4-step sequence. Free radical oxidn. of II by means of iodine and iodosobenzene diacetate under UV light gave a model 9-decanolide III in...

A dithioacetalization procedure at low temp. using TMSOTf as the promoter is described. This method proved highly efficient for unprecedented transprotection of ketone enol ethers and was successfully applied to polyfunctional sensitive substrates. [on SciFinder(R)]

The [4+2] heterocycloaddn. reaction between (E)-γ-substituted β-unsatd. α-oxo esters and cyclic and acyclic ketone enol ethers afforded heteroadducts in high yields when either [Eu(fod)3] or SnCl4 were used as the catalyst: with Me (E)-benzylidenepyruvate, the two catalytic modes displayed divergent stereoselectivities. In the case of the heterocyc...

O-t-Butyldimethylsilyl enol ethers derived from simple cyclic ketones acted as efficient dienophiles in the Lewis acid-catalyzed heterocycloaddns. with methylbenzylidenepyruvate 1. Good selectivities were obsd. with cyclohexanone derivs. E.g., methylbenzylidenepyruvate reacted with dienophile enol ether, e.g., (1-cyclohexen-1-yloxy)(t-butyl)dimethy...