Jean-Pierre Dulcere

Vilsmeier reagent for a high yield conversion of aldoximes to nitriles

Abstract Chloromethylenedimethylammonium chloride was used to convert aldoximes 1b-g to nitriles 2b-g .

Synthesis of silyl-substituted vinylallenes

The coupling between the 5-chloro-3-en-1-ynes 1a - 1e and trimetylchlorosilane gives rise to the vinylallenes 2a - 2e substituted by a trimethylsilyl group on the allenic moiety.

Preparation d'acyl-4 methylene-3 tetrahydrofuranes: Un access aux α-methylene γ-lactones et butenolides fonctionnalises

Abstract The cohalogenation of α,β-unsaturated ketones 1 (a–j) by NBS in propargyl alcohol affords α-halo β-alcoxyketones 2 (a–j). Radical cyclisation of compounds 2 (a–j) gives rise to 4-acyl 3-methylene tetrahydrofurans 3 (a–j), according to a regio and diastereoselective process.

Allene oxide. V - oxidation of β-allenic alcohols bearing a trimethylsilyl group on the allenic moiety. Probe of a concerted mechanism in the δ-lactones formation.

Abstract β-allenic alcohols substituted by a trimethylsilyl group at the −1 or −3 position respectively give rise to γ or δ-lactones. In the last case, a concerted mechanism is involved

A new synthetic route to β-bromoprop-2-ynyl mixed acetals and bromovinyl bis-allyl mixed acetals, precursors of α-methylene-γ-butyrolactones

Cohalogenation by N-bromosuccinimide in methanol of β-bromoallenyl ethers (3a–g) or allyl allenyl ethers (8d–f) affords unsaturated halogeno-compounds (5a–g) or (9d–f) which are converted via homolytic carbocyclization into α-methylene-γ-butyrolactones (7a–g).

Diels–Alder intramolecular cycloaddition of vinylallenyl cycloalken-3-yl ethers

Cohalogenation of cycloalkenes 1 by N-bromosuccinimide (NBS) in 4-methylpent-4-en-2-yn-1-ol affords β-bromopent-4-en-2-ynyl ethers 2 which undergo facile base-promoted consecutive dehydrohalogenation-isomerization-intramolecular Diels–Alder cycloaddition leading to tricyclic conjugated enol ethers 6.

A new synthetic route to 2,5-dihydrofurans

ButOK–dimethyl sulfoxide-catalysed selective isomerization of 3-methylene tetrahydrofurans 1 provides a new convenient route to 2,5-dihydrofuran 2 precursors of furan-2(3H)-ones 8 or furans 4 or 9.

Cohalogenation des olefines: application a la synthese d'alcools allyliques

Abstract Alkenes 1 a-f are converted in three steps into the allyl alcohols 4 a-f; the cohalogenation of alkenes by NBS in alcohols constitutes the first step of this synthesis.

La cohalogénation des oléfines dans l'oxyde d'éthylène: nouvel accès aux éthers vinylallyliques

Resume Alkenes 1 a-i are converted in two steps into the allyl vinyl ethers 3 a-i. The claisen rearrangement of 3 a-1 affords the corresponding γ, δ-unsaturated aldehydes.

Tandem oxa-Michael addition–SN2′substitution of 4-chlorobut-2-yn-1-ol with nitroalkenes: a total allylic1,3-strain-controlled diastereoselective synthesis of3-vinylidenetetrahydrofurans

Bu t OK-promoted reaction of 4-chlorobut-2-yn-1-ol 1 with nitroalkenes 2 affords 3-vinylidenetetrahydrofurans 3 in good yields with total diastereoselectivity.