Transformation of [6] and [7]metacyclophanols into new strained tricyclic ethers via an intramolecular version of the SN2 reaction
摘要:
Treatment of 2a, b with LiAlH4 gave the [6] and [7]metacyclophanols 4 and 8 in good yields. The reactions of 4 and 8 with MeSO2Cl in the presence of Et3N in CH2Cl2 rapidly proceeded to give the corresponding strained tricyclic ethers 6 and 10 via an intramolecular version of the S(N)2 reaction. This stereospecific cyclic ether formation in the mesylate molecules 5 and 9 can be rationalized in terms of a short nonbonded length between both reaction centers and a fairly rigid linear relationship between the leaving group and the nucleophilic group.