P. Canonne

Effet du benzene dans la reaction de Grignard sur les nitriles

Resume Use of benzene containing one equivalent of ether as solvent in Grignard reactions of nitriles at room temperature, leads to increased yields of the corresponding ketones compared to results obtained for the same reactions in ether. A useful consequence of this is that undesirable side reactions are virtually eliminated.

Synthesis of chiral 3-substituted 2,4(1H,3H)-quinazolinediones

2-Carbomethoxyphenyl isocyanate and 6-nitro-2-carbomethoxyphenyl isocyanate were generated in situ from half-esters, and then converted into the corresponding quinazolinediones using α-amino acids. This useful annelation process was found to be a general method for the formation of various chiral 3-substituted quinazolinediones

A novel synthesis of unsaturated spiro compounds based on reactions of bifunctional organometallic reagents

Abstract Z-allylic dibromides regio- and stereoselectively prepared were reacted with the sodium enolate of ethyl acetoacetate or di(α-ethoxyvinyl)cuprate to yield, after hydrolysis, and decarboxylation in the case where the enolate of ethylacetoacetate was the nucleophile, the corresponding ketones. After reduction and bromination, the products were converted into the appropriate organometallic compounds and reacted with selected cyclic anhydrides and β-halo-α,β-unsaturated cyclic ketones. The spiro compounds so obtained are key intermediates for the synthesis of naturally occurring spiro sesquiterpenes.

Reactions selectives des organonagnesiens avec les lactols et les lactones. Synthese des diols primaires-secondaires

Abstract The reactionz of organomagnesium compounds with cyclic lactols and the phthalde show a high chemioselectivity and provide respectively corresponding monoalkylated cyclic lactones and diols We also observe that the formation of bridged tricyclic lactones stereoselectively yields to the transisomer . In the same way, we describe an easy and general method for the synthesis of diols, precursors of dibromides and cyclic ethers.

A facile and general route to 4-substituted-2 butenolides

Abstract Grignard reagents react with 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride and produce in high yields the corresponding substituted bicyclo-γ-butanolides. These lactones produce the title compounds by retro Diels-Alder reaction during distillation.

Enantioselective synthesis of spiro[4.5]decanone with 2-(S)-methoxy-1,4-dibromobutane

Abstract The reaction of 3-methyl-2-cyclohexen-1-one with 2-(S)-methoxy-1,4-dibromobutane (2) produced spiro[4.5]decanone 3, a key intermediate for the synthesis of spirovetivanes, with regiodifferentiation and stereoselection. Subsequent addition of diisopropoxydimethyltitanium to the carbonyl group furnished compound 6 with diasterofacial selectivity. The same selectivity was observed in the subsequent catalytic hydrogenation.

A convenient synthesis of bridged azatricyclic anhydrides

Abstract Bridged N-protected β-amino acids have been regioselectively prepared from the corresponding bicyclic monoesters. The subsequent cyclisation by thionyl chloride produced the desired bridged azatricyclic anhydrides which are versatile substrates for the synthesis of dipeptides; they are also converted into oxathymine and oxauracil by a thermal [4+2] cycloreversion.

Etude de l'action des alkylmagnesiens primaires et arylmagnesiens sur les anhydrides tricycliques pontes

Resume La reaction des alkylmagnesiens primaires et organomagnesiens aromatiques sur les anhydrides bicycliques pontes adduits du furanne et cyclopentadiene conduit a la formation de lactones tricycliques dialkylees par une double addition du reactif de Grignard sur le carbonyle en passant par un cetocarboxylate. Les lactones conduisent par la reaction retro-Diels-Alder aux butenolides correspondants

Alkylation des lactones tricycliques pontees. Application a la synthese des butenolides trisubstitues en 2 et 4

Abstract Disubstituted endo tricyclic lactones have been prepared by the reaction of primary alkylmagnesium compounds with the endo bicyclo [ 2.2.1 ] hept-5-ene-2, 3 dicarboxylic anhydride. These lactones were alkylated and transformed into corresponding 3,5,5-trialkyl-2(5H) furanones.

The first enantioselective synthesis of (−)-microcionin 2

Abstract An approach known to give regiospecific and stereospecific reaction has been applied to the enantioselective synthesis of the natural (−)-microcionin 2 ( 1 ), a prototype of trans relationship of the methyl groups on the furanosesquiterpenes.