Intramolecular [2 + 2]cycloadditions of dialkylketenes with alkenes. Regiochemistry of intramolecular [2+2]cycloadditions of ketenes with alkenes
作者:Barry B. Snider、Alban J. Allentoff、Marleen B. Walner
DOI:10.1016/s0040-4020(01)81460-5
日期:——
Unsaturated dialkylketenes 7a, 7b and 7c undergo intramolecular [2 + 2]cycloadditions to give 8a (45%), 9b (23%) and 9c (45%). Intramolecularcycloadditions of dialkylketenes give higher yields than intramolecularcycloadditions of monoalkylketenes, even though dialkylketenes are less reactive than monoalkylketenes. An intramolecular competition experiment with ketene 17 establishes that trans-alkenes