Diethylacetylene dicarboxylate

Dodd and co-workers (5) reported the first known synthesis of 11//-indolizino[8,7-h]indoles by the cycloaddition reaction of a nonstabilized ylide 21 and diethylacetylene dicarboxylate (DEAD). The azomethine ylide, formed by the alkylation of the 3,4-dihydro-p-carboline (22) with trimethylsilyl methyl triflate to the triflate salt, followed by in situ desilyation with cesium fluoride, underwent cycloaddition with DEAD at low temperature. The expected major cycloadduct 23 was isolated, along with quantities of a minor product 24, presumed to have been formed by initial reaction of the ylide with 1 equiv of DEAD and the intermediate undergoing reaction with a further equivalent of DEAD before cyclization. Dodd offers no explanation for the unexpected position of the double bond in the newly generated five-membered ring, although it is most likely due to post-reaction isomerization to the thermodynamically more stable p-amino acrylate system (Scheme 3.5). 

When refluxed for 15 h in xylene, aryl-substituted /V-(trimethylsilylmethyl)imines rearrange to /V-tri methyl si I y lazi ridines with high c/s-selectivity. It has been demonstrated that the reaction proceeds via an ylid that can be trapped with diethylacetylene-dicarboxylate (DEAD), for example. The more stable frans-geometry of the ylid and conrotatory cyclization would be responsible for the c/.v-aziridines. The authors note that no reaction occurs when the reaction is run in a polar solvent such as THF or acetonitrile, and that treatment of the imine with cesium fluoride in THF leads to protodesilylation only, as does 1 equiv. of water in HMPA.329... 

To identify potential dipolarophiles, a series of competition experiments were performed (Scheme 7.45).117 While inclusion of terminal acetylenes resulted in preferential silacyclopropene 99c or dioxosilacyclopentane 161 formation, the desired oxasilacylopentene (163) was obtained when diethylacetylene dicarboxylate was added... 

Diethylacetylene dicarboxylate was reduced in a four-electron process to diethyl-succinate. Yields of the isolated product typically ranged from 50 to 70%, with hydrogen evolution identified as the main cause for the drop in current efficiency. Side products arising from hydrodimerization or polymerization were not observed. 

The electrochemical reduction of unsaturated organic compounds to paraffins is usually undertaken in nonaqueous solutions. However, the use of ultrasound allows voltammetry to be performed in a more ecofriendly manner by using a sonoemulsion of the substrate in water, so eliminating the need for the nonaqueous solvent. For example, voltammograms for the reduction of diethylmaleate, diethylfumarate, and diethylacetylene dicarboxylate in the form of microscopic droplets generated by applying power... 

The IR-data show ed that the ketone group of serratinine is present in a five-membered ring. Examination of the IR spectra of the ketones deriv ed from the secondary alcohol functions implied that both are present in six-membered or larger rings. This conclusion was confirmed when CXXVI, obtained by dehydration of CXVIII, was treated with diethylacetylene dicarboxylate and gave in one step 4-methyl-phthalate. Cyclohexadienes are reported to react in this fashion. One... 

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