title: A practical catalytic method for preparing highly substituted cyclobutanes and cyclobutenes.
abstract: Tf2NH, an organic acid, efficiently catalyzes (2 + 2) cycloaddition reactions of silyl enol ethers with acrylates or propiolate. The process affords highly substituted cyclobutanes in high yield with high stereoselectivity under practical and environmentally benign conditions. Application for the formation of terpene skeletons and multigram synthesis of four-membered carbocycles were demonstrated.
authors.affiliation: Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama Sendai 980-8578, Japan.
authors.forename: Kazato
authors.initials: K
authors.lastname: Inanaga
authors.forename: Kiyosei
authors.initials: K
authors.lastname: Takasu
authors.forename: Masataka
authors.initials: M
authors.lastname: Ihara
mesh_terms: D002384:Catalysis; D003503:Cyclobutanes / Q000138:chemical synthesis*; D003516:Cycloparaffins / Q000138:chemical synthesis*; D007094:Imides / Q000737:chemistry; D008698:Mesylates / Q000737:chemistry
chemical_list: D003503:Cyclobutanes; D003516:Cycloparaffins; D007094:Imides; D008698:Mesylates; C012077:trifluoromethanesulfonic acid