Synthesis of Veprisine Dimers and the Formation of a Novel Cyclic Tetramer from Precocene I

Article abstract of DOI:10.1016/S0040-4020(01)89446-1

Thermolysis of veprisine afforded vepridimerines A-D and in addition, a new dimer, vepridimerine E.The full details of the 1H and 13C NMR spectroscopic properties of vepridimerines A-E are presented.Acid treatment of veprisine gave another new dimer, diveprisine, analogous to the known precocene II dimer.Under the same conditions precocene I was transformed into a cyclic tetramer.High field NMR examination of the coumarin dimer, reported by Barnes et al. in 1963, confirmed the assigned structure.