Butenes, addition pyrolysis

The simplest pentalene yet known, the 1-methyl derivative, has been prepared by making recourse to a retro-Diels-Alder degradation as the generative step under flash vacuum pyrolysis conditions (Scheme 27).234 Addition of 4-bromo-3-buten-2-... 

The photolysis and pyrolysis of difluorodiazirine has been shown to involve difluoromethylene and stereospecific addition to 2-butene indicates that it is probably in a singlet state. In argon or nitrogen matrices, Cp2 has been detected by spectroscopic measurements . Products arising from the thermolysis or photolysis of fluoromethoxydiazirine, cyanofluorodiazirine, difluoroaminodiazirine and chlorofluorodiazirine have been reported the main feature of these reactions is that the intermediate carbene in all cases can be trapped by olefin reagents, whereas fluorocarbenes from other sources are quite unreactive. 

Thus, europium loaded gels were prepared. Some of them were dried by solvent evacuation at CO2 supercritical conditions to obtain the Eu-organic aerogeh After pyrolysis at 1050 °C a Eu-carbon aerogel was obtained (entries 2-4 of Table 5.7). The materials were tested as catalysts in Michael additions (Scheme 5.11). We performed the reaction of ethyl 2-oxocyclopentanecarboxylate and 3-buten-2-one... 

Most of the work on halocarbenes is concerned with carbenoids. Pyrolysis of chlorodiazomethane leads to a less-selective intermediate than its carbenoid counterpart." Addition to 2-butene is stereospecific, but the syn/anti ratios in various olefins is markedly different." ... 

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