Structures of Angular Pyranocoumarins of Bai-Hua Qian-Hu, the Root ofPeucedanum praeruptorum1

Abstract
Three new angular-type dihydropyranocoumarins, peucedanocoumarin I (1), peucedanocou-marin II (2), peucedanocoumarin III (3), and a known coumarin having the same skeleton, pteryxin (4), were isolated from the crude drug “Bai-Hua Qian-Hu“ of the Q-II type series, which is the root of Peucedanum praeruptorum Dunn. (Umbelliferae). The chemical structures of 1, 2, and 3 have been established by physicochemical methods to be 3′ (S)-2-methylbutyryloxy-4′-(R)-acetoxy-3′,4′-dihydroseselin, 3′(S)-acetoxy-4′(R)-angeloyloxy-3′,4′-dihydroseselin, and 3′(S)-acetoxy-4′(R)-tigloyloxy-3′,4′-dihydroseselin, respectively.