Facile Synthesis and Preferred Conformation Analysis of Cyclododecenobindene

摘要

Using methanesulfonic acid as a catalyst, a series of cyclododecenobindene derivatives were synthesized by the cyclization of α-benzylcyclododecanones, which were prepared by the reactions of cyclododecanones with a variety of substituted benzyl chlorides or bromides using NaH as a base. Their structures were confirmed by mp, IR spectra, 1 H-NMR, 13 C-NMR, MS, and x-ray diffraction. The preferred conformations were analyzed by crystal structure, 1 H-NMR and quantum chemistry calculations, and compared with the x-ray diffraction structure of 2,3,5,6-bis(ortho-1,10-decylidene)dihydropyrazine. The results showed that the cyclododecene moiety adopted a preferred 1ene2333 conformation, and the substituted groups at aromatic ring had no significant influence on the conformation.