TY - JOUR
T1 - AuBr3- and Cu(OTf)2-catalyzed intramolecular [4 + 2] cycloaddition of tethered alkynyl and alkenyl enynones and enynals
T2 - A new synthetic method for functionalized polycyclic hydrocarbons
AU - Asao, Naoki
AU - Sato, Kenichiro
AU - Menggenbateer,
AU - Yamamoto, Yoshinori
PY - 2005/4/29
Y1 - 2005/4/29
N2 - (Chemical Equation Presented) Treatment of tethered alkynyl enynones 8, in which a carbon chain is attached to the carbonyl group, with a catalytic amount of AuBr3in (ClCH2)2 gave the naphthyl ketones 9 in good to high yields (top-down approach). Analogously, the AuBr 3-catalyzed benzannulations of 10, in which a carbon tether is extended from the alkynyl terminus, also proceeded smoothly, and the cyclized naphthyl ketones 11 were obtained in high yields (bottom-up approach). Similarly, when two kinds of tethered alkenyl enynones 12 and 14 were treated with Cu(OTf)2 catalyst, the corresponding dihydronaphthyl ketone products 13 and 15 were obtained in high yields, respectively. The present formal [4 + 2] intramolecular cycloaddition proceeds most probably through the coordination of the triple bond at the ortho position of substrates to Lewis acids, the formation of benzopyrylium ate complex 16 via the nucleophilic addition of the carbonyl oxygen atom, the reverse electron demand type Diels-Alder addition of the tethered alkynes or alkenes to the ate complex, and subsequent bond rearrangement.
AB - (Chemical Equation Presented) Treatment of tethered alkynyl enynones 8, in which a carbon chain is attached to the carbonyl group, with a catalytic amount of AuBr3in (ClCH2)2 gave the naphthyl ketones 9 in good to high yields (top-down approach). Analogously, the AuBr 3-catalyzed benzannulations of 10, in which a carbon tether is extended from the alkynyl terminus, also proceeded smoothly, and the cyclized naphthyl ketones 11 were obtained in high yields (bottom-up approach). Similarly, when two kinds of tethered alkenyl enynones 12 and 14 were treated with Cu(OTf)2 catalyst, the corresponding dihydronaphthyl ketone products 13 and 15 were obtained in high yields, respectively. The present formal [4 + 2] intramolecular cycloaddition proceeds most probably through the coordination of the triple bond at the ortho position of substrates to Lewis acids, the formation of benzopyrylium ate complex 16 via the nucleophilic addition of the carbonyl oxygen atom, the reverse electron demand type Diels-Alder addition of the tethered alkynes or alkenes to the ate complex, and subsequent bond rearrangement.
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U2 - 10.1021/jo0500434
DO - 10.1021/jo0500434
M3 - Article
C2 - 15845007
AN - SCOPUS:17744383592
VL - 70
SP - 3682
EP - 3685
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 9
ER -