Circular dichroism, optical rotatory dispersion and absolute configuration of flavanones, 3-hydroxyflavanones and their glycosides

Flavanones of 2S configuration and 3-hydroxyflavanones of 2R,3R configuration, having equatorial 2-aryl substituents in the former or diequatorial 2,3-substituents in the latter, exhibit a positive Cotton effect due to the n → π* transition (∼ 330 nm) and a negative Cotton effect in the n α π* region (∼ 280–290 nm). Flavanone glycosides possessing chiral aglycones show Cotton effects quite similar to their optically active aglycones while...