Pescitelli Gennaro, Berova Nina, Xiao Tom L, Rozhkov Roman V, Larock Richard C, Armstrong Daniel W
Dept. of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA.
Org Biomol Chem. 2003 Jan 7;1(1):186-90. doi: 10.1039/b207652g.
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.
一种苯基取代的手性二氢呋喃当归素，即4-甲基-8-(2-E-苯乙烯基)-8,9-二氢-2H-呋喃并[2,3-h]-1-苯并吡喃-2-酮，以外消旋形式合成，通过高效液相色谱手性分离进行拆分，并通过非经验激子手性方法确定其绝对构型。通过核磁共振和分子建模方法研究了溶液构象：通过分子力学和密度泛函理论方法发现的两个极小值与观察到的1H-1H 3J耦合常数和核Overhauser效应相符。第二个洗脱对映体的实验圆二色光谱在230至350 nm之间显示出一个正双峰（振幅A = + 15.7）；通过应用激子手性方法，确定该对映体在C8处的绝对构型为(S)。实验光谱与使用密度泛函理论计算的几何结构通过德沃耦合振荡器计算评估的光谱非常吻合。
