Ring expansion of functionalized octahydroindoles to enantiopure cis-decahydroquinolines.
A new synthetic entry to enantiopure cis-decahydroquinolines is reported. Endo and exo derivatives of cis-1-benzyl-2-(hydroxymethyl)octahydroindol-6-one ethylene acetal undergo ring enlargement upon treatment with TFAA and then Et3N (thermodynamic conditions) to give enantiopure 1-benzyl-3-hydroxydecahydroquinolin-7-one derivatives in 77 and 82% yield, respectively. For 2-(1-hydroxyethyl) analogues, the best synthetic result is obtained from the (2S,1'R) endo isomer, which under kinetic reaction conditions (MsCl, THF, -20 degrees C, then AgOAc at rt ) gives the expanded product in 54% yield.
Mena
Marisa
M
Laboratori de Química Orgànica, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028-Barcelona, Spain.
Bonjoch
Josep
J
Gomez Pardo
Domingo
D
Cossy
Janine
J
D006859:Hydrogen / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D007700:Kinetics; D008745:Methylation; D015394:Molecular Structure; D011804:Quinolines / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
D007211:Indoles; D011804:Quinolines; D006859:Hydrogen; C037219:quinoline