tailieunhanh - Structure elucidation of a new sesquiterpenoid from Litsea vertcillata hance (lauraceae)

Verticillatol was isolated from Litsea verticillata as a new eudesmane sesquiterpenoid. Its plane structure was determined by means of 1 H, 13 C, COSY, HMBC, HMQC spectroscopy. The relative stereostructure was deduced from NOESY data and induced solvent shift effect. Finally, its absolute configuration was known through analysis of 1H-NMR spectra of its Mosher esters. | Journal of Chemistry Vol. 40 P. No. DB P. 176 -179 2002 STRUCTURE ELUCIDATION OF A NEW SESQUITERPENOID FROM LITSEA VERTCILLATA HANCE LAURACEAE Received 29-10-2001 VU DINH HQANG1 NGUyEN VAN HƯNG1 HARRy H. S. FQNG2 PHAM GIA DIEN1 institute of Chemistry NCST Vietnam 2College of Pharmacy the University of Illinois at Chicago USA SUMMARY Verticillatol was isolated from Litsea verticillata as a new eudesmane sesquiterpenoid. Its plane structure was determined by means of 1H 13C COSY HMBC HMQC spectroscopy. The relative stereostructure was deduced from NOESY data and induced solvent shift effect. Finally its absolute configuration was known through analysis of 1H-NMR spectra of its Mosher esters. I - INTRODUCTION As a part of International Cooperative Biodiversity Group ICBG the collaborative project between institutions in the USA Vietnam and Laos Litsea verticillata was collected from Cuc Phuong National Park Vietnam for study. There is no phytochemical work on the plant has been reported previously. The chloroform extract of the plant material was subjected to bioassay-guided fractionation in attempt to identify anti-HIV constituents. A new sesquiterpenoid isolated from the plant showed interest in term of application of modern NMR methods for its structure elucidation. II - RESULT AND DISCUSSION Verticilatol 1 was isolated as colorless oil . . .25 with negative optical rotation a D - . The electron impact EI-MS of 1 showed a molecular ion M peak at m z 238. The molecular formula C15H26O2 of 1 was determined from the molecular ion peak observed in the EI-MS and by HREI-MS. The 176 IR spectrum of 1 showed absorption bands ascribable to hydroxyl and olefin function at 3432 and 1709 cm. The 1H-NMR and 13C-NMR spectra of 1 showed signals assignable to a tertiary methyl Ỗ s 14-H3 two secondary methyls Ỗ both d J Hz a methyl bearing hydroxyl group Ỗ dd J Hz 1-H and an exomethylene Ô both br s together with 5 methylenes 2 3 6 8