Stereoselective formation of tri- and tetracycles by samarium diiodide-induced cyclizations of naphthyl-substituted ketones.
[reaction: see text] Samarium diiodide promotes smooth reductive cyclizations of gamma-naphthyl-substituted ketones to afford tri- and tetracyclic compounds in high yields and with excellent stereoselectivities. Cyclic ketones furnish steroid-like compounds with "unnatural" cis/cis annulation of rings B/C/D. The remaining styrene-type double bond of ring B allows further stereoselective reactions. Cases with matched and mismatched relative configuration could be identified leading to dramatic differences in the ring closure ability.
Berndt
Mathias
M
Institut für Chemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany.
Hlobilová
Iva
I
Reissig
Hans-Ulrich
HU