title: Ring expansion of lactones and lactams via propiolate 1-carbon intercalation.
abstract: Readily available five- and six-membered lactones and N-sulfonyllactams undergo efficient addition of t-butyl propiolate, and the resulting adducts undergo cycloisomerization to six- and seven-membered cyclic ethers or amines in the presence of pyridinium acetate. The ring expansion process occurs in generally good yields and is proposed to involve a nucleophilic catalysis mechanism.
authors.affiliation: Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB, T6G 2G2, Canada.
authors.forename: Tina N
authors.initials: TN
authors.lastname: Grant
authors.forename: Chantel L
authors.initials: CL
authors.lastname: Benson
authors.forename: F G
authors.initials: FG
authors.lastname: West
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D003500:Cyclization; D007364:Intercalating Agents / Q000737:chemistry*; D007536:Isomerism; D007769:Lactams / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry*
chemical_list: D000480:Alkynes; D007364:Intercalating Agents; D007769:Lactams; D007783:Lactones; D011422:Propionates; D002244:Carbon; C011537:propiolic acid