Regiocontrolled intramolecular cyclizations of carboxylic acids to carbon-carbon triple bonds promoted by acid or base catalyst.
We systematically investigated, for the first time, the relationship between regioselectivity and acid/base effects in the cyclization reactions between carboxylic acids and carbon-carbon triple bonds. We found novel acid- and base-promoted cyclizations to selectively give isocoumarin or pyran-2(2H)-one and phthalide or furan-2(5H)-one skeletons, respectively, and established a catalytic version of regioselective heterocyclic ring synthesis. Density functional theory calculations and application to a short route to thunberginol A were also described. [reaction: see text].
Uchiyama
Masanobu
M
Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan. uchiyama@mol.f.u-tokyo.ac.jp
Ozawa
Hiroki
H
Takuma
Kazuya
K
Matsumoto
Yotaro
Y
Yonehara
Mitsuhiro
M
Hiroya
Kou
K
Sakamoto
Takao
T
D000900:Anti-Bacterial Agents / Q000138:chemical synthesis; D002264:Carboxylic Acids / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D005663:Furans / Q000138:chemical synthesis; D006571:Heterocyclic Compounds / Q000138:chemical synthesis; D031966:Hydrangea / Q000737:chemistry; D049934:Isocoumarins / Q000138:chemical synthesis; D011714:Pyrans / Q000138:chemical synthesis
D000900:Anti-Bacterial Agents; D002264:Carboxylic Acids; D005663:Furans; D006571:Heterocyclic Compounds; D049934:Isocoumarins; D011714:Pyrans; C079055:thunberginol A