Heating a variety of 2-hydroxybenzyl acetates bearing a range functional groups on the 4- or 5-position of the aromatic ring at 100 ËC in neat γ-methylene-γ-butyrolactone (1.0 M) for 20 hours gives a series of benzannelated [5,6]-spiroketals in 75-89% yield.
Substituents on Quinone Methides Strongly Modulate Formation and Stability of Their Nucleophilic Adducts
作者:Emily E. Weinert、Ruggero Dondi、Stefano Colloredo-Melz、Kristen N. Frankenfield、Charles H. Mitchell、Mauro Freccero、Steven E. Rokita
DOI:10.1021/ja062948k
日期:2006.9.1
and regenerates its QM with a half-life of approximately 5 h. The generality of these effects is demonstrated with a series of alternative quinone methide precursors (QMP) containing a variety of substituents attached at different positions with respect to the exocyclic methylene. The rates of nucleophilic addition to substituted QMs measured by laser flash photolysis similarly span 5 orders of magnitude