Synthesis and Properties of α,α-Bis(heteroazulen-3-yl)-1,4-benzoquinonemethides
作者:Shin-ichi Naya、Tetsuhiro Watano、Makoto Nitta
DOI:10.1246/bcsj.76.2035
日期:2003.10
counter-anion by using aq. HBF4 or aq. HPF6 and neutralization. The polarization of 11a–f was evaluated by their 13C NMR and UV–vis spectral data. The thermodynamic stability of the conjugated acid of 11a–f was evaluated to be in the order 11a < 11b < 11c and in the order 11d < 11e < 11f based on their pKa values (<0–5.4) obtained spectrophotometrically. The substituent effect of t-Bu was discussed based on the