Synthesis of (+/-)-likonide B (smenochromene D) using a regioselective Claisen rearrangement, separation of the enantiomers and stereochemical assignment.
A synthesis of the unusual ansa-bridged farnesyl hydroquinone derivative likonide B in racemic form is described. The natural product, also known as smenochromene D, was obtained from geranylacetone by a route in which the key steps are a regioselective microwave-mediated Claisen rearrangement of an aryl propargyl ether to deliver the chromene ring, and macrocyclization via an intramolecular Mitsunobu reaction. Subsequent HPLC on a chiral stationary phase gave the pure (+)- and (-)-enantiomers, that were studied by CD spectroscopy, thereby shedding some light on the true stereochemical nature of the two natural products (-)-smenochromene D and (+)-likonide B.
Bruder
Marjorie
M
School of Chemistry, University of Nottingham, University Park, Nottingham, U.K. NG7 2RD.
Smith
Stephen J
SJ
Blake
Alexander J
AJ
Moody
Christopher J
CJ
D001688:Biological Products / Q000737:chemistry*; D006873:Hydroquinones / Q000138:chemical synthesis* / Q000737:chemistry; D008872:Microwaves; D015394:Molecular Structure; D013237:Stereoisomerism
D001688:Biological Products; D006873:Hydroquinones; C502349:likonide B