Date of Award

1983

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Abstract

Chemical analysis of Calea ternifolia var. calyculata (syn. Calea hypoleuka, Calea salmaefolia, and Calea albida) yielded the known sesquiterpene lactone calein A (21) and the atripliciolide derivatives, 11,13-dyhydro-11(alpha),13-epoxyatripliciolide-8(beta)-O-angelate (51), 11,13-dihydro-11(alpha),13-epoxyatripliciolide-8(beta)-O-methacrylate (52), and 9(alpha)-hydroxy-11,13-dihydro-11(alpha),13-epoxyatripliciolide-8(beta)-angelate (54). In addition, three new germacranolides, 8(beta)-angeloyloxy-9(alpha)-{2-methylbutanoyloxy} ternifolin (32), 8(beta)-angeloyloxy-9-acetoxyternifolin (33) and five furanoheliangolides, 9(alpha)-acetoxyzexbrevin (36), 9(alpha)-hydroxyzexbrevin (37), 8(beta)-angeloyloxy-9(alpha)-hydroxycalyculatolide (38), 9(alpha)-hydroxy-11,13-dihydro-11(alpha),13-epoxyatripliciolide 8(beta)-O-methacrylate (55) and 15-hydroxy-11,13-dihydro-11(alpha),13-epoxyatripliciolide (56) were isolated. The structures of the new compounds were elucidated by NMR and mass spectral methods. Single crystal X-ray diffraction of the lactones 36 and 55 established their molecular structure. Calea ternifolia var. ternifolia (syn. Calea liebmanii) provided the new sesquiterpene lactone 2,3-epoxycalein A (81). Epoxidation of calein A (21) gave the epoxyangelate derivative (91) but not the expected 2,3-epoxycalein A (81). Acid-mediated chromate oxidation of 8(beta)-O-angeloyloxy-9(alpha)-acetoxy-ternifolin (33) provided the furan-type germacranolide (89). The isolation and structure determination of two new guaianolides, pumilin (95) and 3(alpha)-epoxypumilin (94) from Berlandiera texana and B. lyatra are described. Their structures were determined by NMR and mass spectral methods, and single crystal X-ray analyses. Epoxidation of dihydrosantamarine tosylate (119) followed by treatment with aluminum isopropoxide gave in high yield (11S)-1(beta)-tosyl-3(alpha)-hydroxyeudesmano-4(15)-eno-12,6(alpha)-lactone (111). The latter compound was also obtained in good yield from dihydroreynosin tosylate (117) by SeO(,2) oxidation. Hydrogenation of lactone 111 with Adam's catalyst provide the (11S)-1(beta)-tosyl-3-hydroxeudemano-12,6(alpha)-lactone (121). Based-mediated fragmentation reactions of (11S)-1(beta)-tosyl-3-hydroxyeudesmano-4(15)-eno-12,6(alpha)-lactone 111 and (11S)-1(beta)-tosyl-3-hydroxyeudesmano-12,6(alpha)-lactone (121) using t-BuOK in t-BuOH provided 15-oxo-saussurea lactone (112) and the hemiacetal (142), respectively. Hydroboration-oxidation of the mesylate of dihydrosantamarine (115) gave a 1,3-elimination product, the cyclopropyl-type acid (131) in low yield.

Pages

174

DOI

10.31390/gradschool_disstheses.3895

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