intramolecular O–C coupling product 2, which has a spiro skeleton in good yield; variable temperature 1H NMR measurements indicated that compounds 2 are interconvertible by a thermal [3.3] sigmatropic rearrangement, and the activation free energies for the [3.3] sigmatropic rearrangement increased with increasing length of the methylene bridge in compounds 2.
用K 3 [Fe(CN)6 ]氧化二羟基[ n .2]甲基环已烷1可以得到分子内的O-C偶联产物2,该产物具有螺旋骨架,收率很高。可变温度1 H NMR测量表明,化合物2通过热[3.3]σ重排可相互转换,并且[3.3]σ重排的活化自由能随化合物2中亚甲基桥长度的增加而增加。
Medium-sized cyclophanes. 16. Bromination of 8,16-dihydroxy[2.2]metacyclophanes