Diels-Alder 반응을 통한 Cycloadducts of Bicyclolactone의 입체 이성질체 구조 연구

초록

Bicyclolactones obtained from the Diels-Alder cycloaddition of 3,5-dibro -mo-2-pyrone can be changed into aryl bicyclolactones. by cross coupling reactions under various palladium catalyst. Bromo-bicyclic diene furnished two different diastereomers endo-form (62%) and exo-form (38%) upon cycloadditions with N-Et maleimide (NEM), and their stereochemistries were identified with NMR In this study, The NMR signal assignments of each isomer was completely accomplished with COSY, TOCSY, NOESY and ROESY. Distance of numerous protons were obtained based on the NOE cross peak intensities of NOESY spectrum. On the basis of these distance data, distance geometry (DG) and molecular dynamics (MD) were carried out to determine the isomer structures of endo-form and exo-form