Assignment of absolute configuration of a chiral phenyl-substituted dihydrofuroangelicin.
A phenyl-substituted chiral dihydrofuroangelicin, 4-methyl-8-(2-E-phenylethenyl)-8,9-dihydro-2H-furo[2,3-h]- 1-benzopyran-2-one, synthesized in racemic form, has been resolved by HPLC chiral separation, and its absolute configuration determined by the non-empirical exciton chirality method. The solution conformation has been investigated through NMR and molecular modeling methods: two minima found by molecular mechanics and DFT methods are in keeping with observed 1H-1H 3J coupling constants and NOE effects. The experimental CD spectrum for the second eluted enantiomer shows a positive couplet between 230 and 350 nm (amplitude A = + 15.7); by application of the exciton chirality method, the absolute configuration of this enantiomer at C8 is determined as (S). The experimental spectrum is in very good agreement with the one evaluated by means of DeVoe coupled-oscillator calculations, using the DFT calculated geometries.
Pescitelli
Gennaro
G
Dept. of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA.
Berova
Nina
N
Xiao
Tom L
TL
Rozhkov
Roman V
RV
Larock
Richard C
RC
Armstrong
Daniel W
DW
D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004583:Electrons; D011564:Furocoumarins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D011487:Protein Conformation; D014466:Ultraviolet Rays
C480179:4-methyl-8-(2-E-phenylethenyl)-8,9-dihydro-2H-furo(2,3-h)-1-benzopyran-2-one,; D011564:Furocoumarins; C011659:angelicin