Silaheterocyclen II. Erzeugung und Cycloadditionsreaktionen der Neopentylsilaethene (R = H, Me)

Article abstract of DOI:10.1016/0022-328X(87)87159-0

The monosilacyclobutanes (3) and (4) react with LiBu^t in pentane to yield the neopentylsilaethenes (1) and (2), respectively.Without suitable reactants, 1 and 2 undergo cyclodimerization to 2,4-dineopentyl-1,3-disilacyclobutanes; in the presence of organic dienes they form cycloaddition compounds: with cyclopentadiene only <2 + 4> products are obtained, with cyclohexa-1,3-diene <2 + 2>- and <2 + 4>-cycloaddition reactions occur at comparable rates; in the reaction with norbornadiene the <2 + 2 + 2>- is favoured over the <2 + 2>-cycloaddition, whereas with 2,3-dimethyl-1,3-butadiene the <2 + 2>-process together with the ene-reaction predominate.The <2 + 2>-cycloadducts indicate a multistep-pathway, probably with participation of lithiated species, whereas the <2 + 4>- and <2 + 2 + 2>-cycloaddition reactions confirm that the silaethenes 1 and 2 are formed as reactive intermediates.