Nucleophilic lewis base dependent addition reactions of allenoates with trifluoromethylated cyclic ketimines.
A detailed investigation on the different reactivity patterns shown by phosphorus- and nitrogen-containing Lewis base catalysts in the reactions of allenoates with cyclic trifluoromethyl ketimines was accomplished. With PPh3, [3 + 2] annulations proceeded smoothly to afford dihydropyrrole derivatives in excellent yields. Under the catalysis of DABCO, [2 + 2] annulations occurred, producing azetidine derivatives in good to high yields. However, in the presence of pyridine, α,α'-disubstituted allenoates were obtained in very high yields via aza-Morita-Baylis-Hillman reactions. These studies provide an opportunity for diverse synthesis of a variety of N-heterocyclic compounds from the same starting materials.
Department of Chemistry, Key Laboratory of Systems Bioengineering (The Ministry of Education), Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Tianjin 300072, People's Republic of China.
Li-Jun
LJ
Yang
Shen
S
Li
Shuai
S
Wang
Jing
J
Nie
Jun-An
JA
Ma