title: Yb(OTf)3-catalyzed reactions of 5-alkylidene Meldrum's acids with phenols: one-pot assembly of 3,4-dihydrocoumarins, 4-chromanones, coumarins, and chromones.
abstract: [reaction: see text] The Yb(OTf)3-catalyzed annulation reactions of phenols with 5-alkylidene Meldrum's acids enabled the synthesis of structurally diverse heterocycles in high isolated yields. A series of 4-substituted 3,4-dihydrocoumarins, 2,2-disubstituted 4-chromanones, coumarins, and 2-substituted chromones were readily and efficiently assembled, including the naturally occurring coumarins citropten, scoparone, and ayapin. Addition of phenols to biselectrophilic 5-alkylidene Meldrum's acids proceeded through two distinct multibond-forming modes: Friedel-Crafts C-alkylation/O-acylation and Friedel-Crafts C-acylation/O-alkylation. The regioselectivity of the catalytic annulation reaction was controlled by the degree of substitution on the alkylidene moiety.
authors.affiliation: Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. efillion@uwaterloo.ca
authors.forename: Eric
authors.initials: E
authors.lastname: Fillion
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Dumas
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Kuropatwa
authors.forename: Neil R
authors.initials: NR
authors.lastname: Malhotra
authors.forename: Tamsyn C
authors.initials: TC
authors.lastname: Sitler
mesh_terms: D000143:Acids / Q000737:chemistry*; D000475:Alkenes / Q000737:chemistry*; D000880:Anthraquinones / Q000737:chemistry*; D002384:Catalysis; D002867:Chromones / Q000737:chemistry*; D003374:Coumarins / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D000143:Acids; D000475:Alkenes; D000880:Anthraquinones; D002867:Chromones; D003374:Coumarins; D009942:Organometallic Compounds; D010636:Phenols; C469373:chaetomanone; D006859:Hydrogen; C030123:coumarin; D015018:Ytterbium