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[摘要]：Dimerizations of C4 precursors RC=CC=CTMS [R = C6H5 (1), p-CH3C6H5, (2), 4-n-C5H11C6H4 (3), C6H9 (4), p-CH3OC6H4 (5), p-C6H5COC6H4 (6), p-NO2C6H4 (7), and p-NCC6H4 (8)] by Hay coupling with in situ deprotection gave stable octatetraynes R(C=C)4R (18-C8-18) in 4280?% yields as light yellow to brown powders. The same tetraynes were next synthesized from the same C4 precursors by an alternative MoriHiyama method that typically utilizes trimethylsilyl-substituted alkynes without prior deprotection. The latter protocol proved useful and gave the expected products but with lower yields of 874?%. The resulting tetraynes were characterized by spectroscopic methods and in some cases by X-ray crystallography. In the cases of 1-C8-1 and 3-C12-3, close analysis of the crystal data showed high degrees of carbon chain linearity, with % contraction indexes of 0.13?% and 0.19?%, respectively. The chains were more strained in the cases of 6-C8-6 (0.34?%) and 3-C8-3 (0.68?%). Deeper analysis of packing motifs revealed 3-C12-3 to be a very promising candidate for topochemical 1,4-polymerization. |
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