Fragmentation Order Determined by Linkage Site Isomer at Remote Moiety: Experimental and Theoretical Studies II

摘要

The ultimate goal of this project is to gain a general understanding of how the order of fragmentation reactions become dependent upon an seemingly minor difference in linkage site to a remote moiety. The chaste tree, Vitex angus-castus Linn. (height: 2-3 m), is distributed about the Mediterranean region, Southern Europe and Central Asia [1]; it is also cultivated in Jiangsu Province and Shanghai City of China. The fruit of V. agnus-castus is a popular phytomedicine in Europe for the treatment of hormonal imbalance syndromes in women [2,3]. Isolated from n-hexane extracts of its fruit are several novel labdane diterpene lactone/lactams [4]. MS/MS of the protonated molecular ions of these compounds exhibit an unusual dependence of fragmentation sequence upon the linkage site isomer at the gamma-lactone/lactam, whether 2' or 3'.