TY - JOUR

T1 - Nucleophilic cycloaromatization of ynamide-terminated enediynes

AU - Poloukhtine, A.

AU - Rassadin, V.

AU - Kuzmin, A.

AU - Popik, V. V.

PY - 2010

Y1 - 2010

N2 - Introduction of a nitrogen atom at one of the acetylenic termini of 10-, 11-, 12-, and 13-membered benzannulated cyclic enediynes results in a complete suppression of the conventional radica Bergman reaction in favor of a polar cycloaromatization. The latter reaction is catalyzed by acid and proceeds via initial protonation of an ynamide fragment. The resulting ketenimmonium cation then cyclizes to produce naphthyl cation, which rapidly reacts with nucleophiles or undergoe Friedel-Crafts addition to aromatic compounds. In alcohols, addition of the nucleophilic solven across the activated triple bond competes with the cyclization reaction. The ratio of cyclized to solvolysis products decreases with the increase in ring size.

AB - Introduction of a nitrogen atom at one of the acetylenic termini of 10-, 11-, 12-, and 13-membered benzannulated cyclic enediynes results in a complete suppression of the conventional radica Bergman reaction in favor of a polar cycloaromatization. The latter reaction is catalyzed by acid and proceeds via initial protonation of an ynamide fragment. The resulting ketenimmonium cation then cyclizes to produce naphthyl cation, which rapidly reacts with nucleophiles or undergoe Friedel-Crafts addition to aromatic compounds. In alcohols, addition of the nucleophilic solven across the activated triple bond competes with the cyclization reaction. The ratio of cyclized to solvolysis products decreases with the increase in ring size.

M3 - Article

VL - 75

SP - 5953

EP - 5962

JO - Journal of Organic Chemistry

JF - Journal of Organic Chemistry

SN - 0022-3263

IS - 17

ER -