Synthesis and properties of 1,6-difunctionalized cyclodeca-3,8-diynes.
The reaction of tert-Bu acetate with 1,4-dibromobut-2-yne in the presence of LDA yielded 1,6-di(tert-butyl)cyclodeca-3,8-diyne-1,6-dicarboxylate (I). The 1,6-di(tert-butyl) groups of I were transferred to bis(hydroxymethyl), bis(bromomethyl) (II) , bis(cyanomethyl), dicarbaldehyde, and bis(methoxyvinyl) groups. In case of II the two diastereomers [cis(a,e), trans(a,a)] were sepd. From cis-II and a trans-biscyanide compd. (III) we were able to obtain detailed structural parameters by means of X-ray crystallog. By means of temp. dependent NMR spectroscopy of III we estd. the activation energy for the chair-boat conversion to be 10.5 kcal/mol.
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