Chiroptical study of O-heterocyclic compounds, secondary mono-alcohols and primary monoamines

摘要

Starting from cholesterol (1), model compounds containing 2,3-dihydrobenzo[b]furan or 4H-benzopyran chromophores of known configurations and rigid conformations (6, 10 and 7) were synthesized in a stereocontrolled sequence. A helicity rule was established for the 2,3-dihydrobenzo[b]furan chromophore (P/M helicity of the heteroring gives rise to negative/positive 1Lb-band CD) on the basis of which the configurational assignment of norneolignans 11-13 isolated from Krameria cystisoides were revised. The synthesis and configurational assignment of the tetrahydro-2,6-methano-1-benzoxocine derivative (-)-14, homochiral with the cholestane derivative 7, was performed which allowed the study of the contribution of the chiral third and fourth sphere to the 1Lb-band CD of the 4H-benzopyran chromophore. With the use of zinc porphyrin tweezer 20, an excition chirality CD method was introduced for the configurational assignment of secondary monoalcohols and primary monoamines and its applicability was proved by the study of compounds with known configuration.