Jean-Louis Ripoll

The syntheses of 6-methylene-2,4-cyclohexadien-1-imine and related o-quinonoids by FVT of 1-hetero-1,2,3,4-tetrahydronaphthalenes

Abstract Flash vacuum thermolysis (≈ 1000 °C/10 −5 hPa) of 1,2,3,4-tetrahydroquinoline, chroman, and thiochroman, led upon loss of ethylene (retro-Diels-Alder reaction) to the o-quinonoids 1–3 . These reactive monomers were identified by IR-UV at −196 °C and/or MS/MS.

The thermal isomerisation benzoazetine - 6-methylene-2,4- cyclohexadien-1-imine: A photoelectron investigation

Abstract The flash vacuum thermolyses of 1,2,3,4-tetrahydroquinoline 3 , o-aminobenzylalcohol 4 and o-aminobenzylamine 5 were performed at temperatures from 923 to 1273 K and monitored by photoelectron spectrometry. While thermolyses at 923-1073 K led to the until now undescribed benzoazetine 2a , 6-methylene-2,4- cyclohexadien-1-imine 1a was obtained at 1173-1273 K.

Synthesis of enethiolisable α-oxothiones by flash vacuum thermolysis

Abstract The retro Diels-Alder reaction of dihydrooxathiins and the retro-ene reaction of α-allylthio-carbonyl compounds were used to synthesise enethiolisable α-oxothiones.

New routes to thioketenes and propadienethione by flash vacuum thermolysis

Abstract The retro-Diels-Alder reaction under flash vacuum thermolysis (FVT) conditions was applied to the synthesis of simple unstabilized thioketenes. Alternatively, these reactive thiocarbonyl compounds were obtained by FVT elimination of methyltrimethylsilyl sulfide from silylated ketene dithioacetals (and for thioketene itself from methyl trimethylsilyl dithioacetate). A synthesis of propadienethione associating these two thermolytic processes is also reported. The thermolysis products were identified by low temperature IR spectroscopy and immediate quenching with gaseous dimethylamine leading to the corresponding thioamides. In the case of propadienethione, further reaction with the methanethiol formed in situ was observed.

A novel route to thioketenes by flash vacuum thermolysis of silylatedketene dithioacetals, synthesis of propadienethione.

Abstract Flash vacuum thermolysis (fvt) of silylated ketene dithioacetals 2 leads to reactive thioketenes 1 . This method, added to a retrodienic reaction, allowedaccess to propadienethione 3 .

The rearrangement of α-imino-thioaldehydes into dihydro-1,3-thiazoles

Abstract α-Imino-thioaldehydes were generated by retro-Diels-Alder reaction under flash vacuum thermolysis conditions. They were found to be unstable and cyclized to 2,3-dihydro-1,3-thiazoles. This cyclization was investigated by ab initio calculations.

Generation by Flash Vacuum Thermolysis and Cyclization of Methyl Penta=2,4=dienedithioate

Abstract Methyl penta-2,4-dienedithioate was generated by flash vacuum thermolysis of two precursors. It was found to be unstable and gave 6-methylthio-(2H)-thiopyran by a pericyclic cyclization.

SYNTHESIS OF THIOALDEHYDES, THIOKETONES AND THIOKETENES BY FLASH VACUUM THERMOLYSIS

Abstract Our last results concerning the synthesis of reactive thiocarbonyl componds using the retro-Diels-Alder reaction under flash vacuum thermolysis conditions are presented.

The first synthesis of Se-methyl carboxylic thionoselenolesters

Reaction of carboxylic thionoesters with dimethylaluminium methylselenolate in diethyl ether gave the corresponding Se-methyl thionoselenolesters in 87–98% yield.

Flash vacuum thermolysis of 5-substituted-4,4-diphenyl-3-oxa-1-azabicyclo[3.1.O]hexan-2- ones. A new route to quinolines.

Abstract Thermolysis of bicyclic carbamates produces quinoline derivatives good yields. A two step reaction is described.