Acidities of glycine Schiff bases and alkylation of their conjugate bases
作者:Martin J. O'Donnell、William D. Bennett、William A. Bruder、William N. Jacobsen、Keith. Knuth、Brigitte. LeClef、Robin L. Polt、Frederick G. Bordwell、Susan R. Mrozack、Thomas A. Cripe
DOI:10.1021/ja00233a031
日期:1988.12
Equilibrium acidities in Me2S0 are reported for six ketimines of the type Ph2C=NCH(R)C02Et and five aldimines, ArCH=NCH(R)C02Et. Changing R in the ketimine from H to Ph increased the pKa by 2.2 units. This surprising acidity decrease for Ph substitution points to a substantial increase in steric effect, as do the increases in pKa of 3.8 and 4.2 units observed for the replacement of hydrogen by Me and