Y. Langlois

α-Hydroxylation of β-dicarbonyl compounds

Abstract Various β-dicarbonyl compounds can be hydroxylated as their silyl enol ethers by m -chloroperbenzoic acid (MCPBA).

Pyridines as precursors of conjugated diene pheromones (II) : Stereoselective synthesis of (7e, 9z)-dodecadien-1-yl acetate, sex pheromone of lobesia botrana☆☆☆

Abstract 2-Alkyl pyridines are convenient precursors of (E, Z) diene ammonium salts which can be substituted by activated Grignard reagents or a lithium diorgano cuprate reagent. The synthesis of (7E, 9Z) dodecadien-1-yl acetate, sex pheromone of Lobesia botrana , is an illustration of this methodology.

New approaches to the synthesis of eburnane alkaloids

Abstract Aldehyde 12 which is a key precursor of the Eburnane alkaloid vincamine 1 has been prepared in two ways. The first one involves a photochemical rearrangement of a spiro oxaziridine intermediate and the second is based on an imino Diels-Alder reaction followed by a stereo and regioselective alkylation.

Chiral α,β-unsaturated oxazolines in the asymmetric diels-alder reaction ☆

Abstract α,β-Unsaturated oxazolines derived from (+)-camphor become powerful dienophiles in asymmetric Diels-Alder reaction after activation with trifluoroacetic anhydride.

New strategy in the stereocontrolled synthesis of the spiro ketal subunit of milbemycins

Abstract A double Baeyer-Villiger oxidation of bicyclo[2,2,1] heptane-2,5-dione and a stereocontrolled alkylation of the dianion derived from 4-pentyn-2-ol are the salient features of a new strategy in the stereocontrolled synthesis of the spiroketal moiety of milbemycins.

Synthesis of the pheromone of the Comstock mealybug via a sila-Cope elimination

Abstract The synthesis of pheromone 1 of the Comstock mealybug has been achieved via a Sila-Cope elimination during which a new type of 1,2 silicon shift was observed.

The fragmentation of NN-dimethyltryptamine oxide and related compounds: a possible implication in indole alkaloid biosynthesis

A modified Polonovski reaction on NN-di-methyltryptamine oxide and related compounds leads to products of fragmentation; the possible role of this new reaction in indole alkaloid biosynthesis is emphasized.

Rearrangement du squelette de la catharanthine

Resume Catharanthine N -oxide 1 leads through a [2,3]-sigmatropic rearrangement to 2 whose structure is established by chemical studies and confirmed by X-ray analysis.

Alkylation of diene allylic tertiary amines with grignard reagents. In situ activation with alkyl chloroformates.

Abstract Diene allylic tertiary amines were substituted with Grignard reagents in the presence of lithium tetrachlorocuprate and alkyl chloroformates. According to the experimental condition employed, this reaction afforded exclusively δ-1 V-alkylation products.

A short stereoselective synthesis of (±)-12-desmethoxy cuanzine

Abstract The synthesis of (±)-12-desmethoxy cuanzine 4 was achieved via a stereoselective alkylation of the mixture of indolo-quinolizidines 5 and 6 followed by an oxidative cyclisation and an alkylation of the aldehyde intermediate 14 by methyl isocyanoacetate.