作者:Mitsunori Oda、Nobue Nakajima、Nguyen Chung Thanh、Takanori Kajioka、Shigeyasu Kuroda
DOI:10.1016/j.tet.2006.05.084
日期:2006.8
Starting from trimethylsilyl enol ether of 1-acetyl-1,3,5-cycloheptatriene, the title 1,1-dimethyl-, 1,1-diethyl-, and 1,1-dipropyl-1H-azulenium cations 6-8 were synthesized in five steps. The order of pK(R)+ values of these cations was found to be 7 > 8 > 6. A comparison of the values between 1, 1-dialkyl- and 1, 1-spiroalkylated 1H-azulenium cations with the same number of carbon atoms at the I-position provided the results of 7 > 1 and 8 < 3. The cation 8 shows a relatively lower pKR+ value to those of 3 and 7 probably due to its slightly bulkier propyl groups from which solvation stabilization of 8 under the conditions suffers. An intermolecular charge-transfer interaction between the cations and dibenzo-24-crown-8 was also studied. (c) 2006 Elsevier Ltd. All rights reserved.