Asymmetric synthesis of a (2Z,7E)-cyclononadiene by an intramolecular cycloalkylation and insight to its conformational properties
Here, we report a novel synthesis of a monosubstituted, enantio- and diastereomerically enriched trans-cyclononadienol. The reaction consists of an enantioselective (-)-sparteine-mediated allylic lithiation of an achiral 7-chlorononadienyl carbamate and a subsequent stereospecific intramolecular allyllithium-allyl chloride coupling. The stereochemical course of the cyclization has been determined, and the high configurative stability of the chiral nine-membered carbocycle has been investigated by kinetic measurements and rationalized by computational calculations.
Deiters
A
Organisch-Chemisches Institut, Westfalische Wilhelms-Universitat Munster, Corrensstrasse 40, D-48149 Munster, Germany.
Muck-Lichtenfeld
C
Frohlich
R
Hoppe
D