Benzotriazole- and 1,2,4-Triazole-Stabilized Allylic Anions: Applications in Syntheses of Functionalized alpha,beta-Unsaturated Ketones, gamma-Lactones, gamma-Lactams, and beta-Substituted Esters.
Deprotonated 1-(benzotriazol-1-yl)-1-ethoxy-2-hexene (7) reacted with alkyl halides, aldehydes, ketones, imines, and alpha,beta-unsaturated esters to give exclusively the alpha-alkylated products 8a-c, 10a,b, 12, 14, 16, and 18a,b, respectively. Without isolation, these products were hydrolyzed under mild conditions to generate the corresponding simple or functionalized alpha,beta-unsaturated ketones 9a-c, 11a,b, 13, 15, 17, and 19a,b. Similar reactions with the phenyl-substituted analog 3-(benzotriazol-1-yl)-3-ethoxy-1-phenyl-1-propene (21) also gave the analogous alpha-products, but they were accompanied by small amount of the gamma-products in most cases. By contrast, deprotonation of the corresponding triazole derivative 29 with butyllithium followed by reactions with alkyl halides, aldehydes, ketones, or imines yielded exclusively gamma-alkylated adducts 32, 34, 36, 38, 40, and 42. Intermediates 32, 34, 36, 38, 40, and 42 were readily converted into beta-substituted esters 33a-c, gamma-lactones 35a,b, 39, 41, and 43, and gamma-lactams 37a-c on hydrolysis.
Katritzky
Alan R.
AR
Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200.
Feng
Daming
D
Lang
Hengyuan
H