J. Gore

Cyclisation d'amines γ et δ-alleniques. Synthese d'alcenyl-2 pyrrolidines et d'alcenyl-2 piperidines.

Abstract The entitled heterocyclic compounds can be obtained with good yields and exclusively with E configuration by the respective cyclisation of secondary γ-allenic and δ-allenic amines promoted by silver nitrate or by mercuric chloride. In the second case, the reaction has to be followed by demercuration in phase transfer conditions.

Easy access to 5-(E)-alkynylidene tetrahydro-2 furanones by a palladium catalyzed process

Abstract Biologically active ynenol lactones 1 are stereospecifically obtained when acetylenic carboxylates are reacted with 1-bromo 1-alkynes in the presence of a palladium(O)-phosphine complex. The reaction is effective only with the potassium carboxylate and the nature of the phosphine is essential for the cyclisation process.

Préparation d'allènes α-triméthysilylés

Resume The Grignard derivative of chloromethyltrimethylsilane reacts with propargylic tosylates or acetates, in the presence of Cu + , leading to α-trimethylsilyl allenes with fair yields.

Palladium-catalyzed synthesis of new unsaturated exo-enol lactones with potential biological activity.

Abstract Various allenenols lactones [5(E)-(2-allenylidene)-tetrahydro-2-furanones] have been synthesized by reacting 4-pentynoic acid and 2-alkynyl acetate in dimethyl sulfoxide in the presence of K 2 CO 3 , Pd(OAc) 2 as the catalyst and tri(2-furyl) phosphine as the ligand. The biological activity of these compounds as protease inhibitors has been proven.

Carbopalladation of functionalized allenes : regioselectivity of the reaction of carbonucleophiles with the intermediate π-allyl palladium complexes.

Abstract A methoxy group orients the carbonucleophile onto the oxygen-substituted secondary carbon. Carbopalladation of functionalized allenes leads to π-allyl palladium complexes, the regiochemistry of which towards carbonucleophiles has been studied : a methoxy group has been demonstrated to reverse the classical regioselectivity and to allow the formation of the more substituted product.

Stereospecific synthesis of arylidene and allylidene cyclopentanes by a palladium-catalyzed cylisation

Abstract Vinyl and aryl halides react with e-acetylenic β-diesters, β-keto esters and βsulfonylesters in the presence of a Pd(o) catalyst leading in good yields to the title compounds. The acetylenic homolog containing an additional carbon leads in the same conditions to a cyclohexane, but this process then competes with the arylation of the terminal acetylenic carbon.

Carbopalladation of β-allenylmalonates : a way to cyclopentenyl or vinylcyclopropyl derivatives.

Abstract The palladium-catalyzed addition of a vinyl or aryl halide to the enolate of β-allenyl malonate 2 leads to the formation of either of the two cyclized products 3 and 4 depending mainly on the bulk of the starting unsaturated halide.

Synthesis of ethynylidene cyclopentanes by a cyclisation catalyzed by the simultaneous presence of palladium (0) and copper (I)

Abstract Ethynylidene cyclopentanes 3 can be formed in 35–71% yield from the reaction of the enolates of compounds such as δ-acetylenic malonates with 1-halogeno-1-alkynes. This reaction requires catalysis by both palladium (0) and copper (I) species.

Chiral recognition of allenic hydrocarbons by 1H NMR

Abstract The syntheses of the allenes (±)- 1 , (±)- 4 and (±)- 6 as well as of the enriched samples (-)- 1 , (-)- 4 and (-)- 6 are described. 1H NMR shifts and splittings induced by a mixture of the achiral salt Ag(fod) and the optically active complex (+)-Yb(hfbc)3 are given. This procedure is recommended by the magnitude of such splittings as a means of determining the enantiomeric purity of 1,3-disubstituted allenic hydrocarbons. The results for (-)- 1 and (-)- 5 represent the first application of this absolute method.

PALLADIUM-MEDIATED CYCLOPENTANATION OF ALKENES BEARING A NUCLEOPHILIC SUBSTITUENT. STEREOCHEMISTRY AND MECHANISM

Abstract The increased facility of the reaction 1 2 simultaneously with the increased nucleophilicity of the malonate, as well as the stereospecificity observed in the case of 3 , led to the conclusion that the cyclisation proceeds by a nucleophilic attack on the double bond activated by a palladium(II) species.