Anti to syn isomerization of oxacalix[4]arene bearing two methyl groups at the intra-annular distal positions

作者：Konishi Hisatoshi^*; Mita Takayuki; Yasukawa Yusuke; Morikawa Osamli; Kobayashi Kazuhiro

来源：Tetrahedron Letters, 2008, 49(48): 6831-6834.

DOI：10.1016/j.tetlet.2008.09.075

• Oxacalixarenene
• Metacyclophane
• Inversion barrier
• VT NMR

The thermal isomerization of anti to syn stereoisomers of oxacalix[4]arene bearing two methyl groups at the intra-annular distal positions was investigated by temperature-dependent NMR spectroscopy. The conversion followed a first-order kinetics, and very slowly proceeded at 473 K in nitrobenzene-d(5) With a half-life of 7.2 h. The free energy of activation (Delta G(-/-) 139 kJ mol(-1)) is much higher than those for the ring inversion of related calix[4]arene derivatives.

• 出版日期2008-11-24