New Germacranolides From Calea ternifolia and the Molecular Structure of 9α-Hydroxy-11,13-Dihydro-11α,13-Epoxyatripliciolide-8β-O-[2-Methylacrylate]

Abstract

Catea ternifolia var. calyculata yielded the new sesquiterpene lactones 9a-acetoxyzexbrevin (1) and 9a-hydroxy-l 1,13-dihydro-l la, 13-epoxy at npliciolide-80-0-[2-methylacrylate] (4). Their structures were characterized by nmr and mass spectral methods and the molecular structure of the latter compound was determined by single crystal x-ray diffraction.Calca ternifolia var. ternifolia contained a mixture of two known calein-type compounds as well as a crystalline mixture of the known 9a-hydroxy-l 1,13-dihydro-atripliciolide-8/S-0-[2-methylacrylate] (3) and 9o-hydroxy-l 1,13-dihydro-l , 13-epoxyatripliciolide-8^-0-[2-methylacrylate] (4). Single crystal x-ray data of a mixture of 3 and 4 were obtained.

The solid-state and solution-state reassigned structures of tagitinin A, a 3,10-epoxy-germacrolide from Tithonia diversifolia, and the interconversion of 3,10-epoxy-germacrolide conformational families via a ring-atom flip mechanism

“…Such a disposition would afford an unfavorable 1,3-cis-diaxial type relationship. On the other hand, the O(6)-oxycarbonyl moiety in the skew-chair-chair (SCC) conformation 3(2H)-furanone family of 3,10-epoxygermacrolide lactones can be either - [32][33][34] or - [10][11][12][13][35][36][37] oriented since SCC represents a conformational change involving a flip of ring-atom C(9), and now the C(14) methyl is equatorial. Finally, one can predict that a epimeric C(15) methyl diastereomer of 7 would not be disposed to retain the TCB conformation since it would then suffer a transannular interaction with the inward pointing axial H(9 ).…”

The genus Calea L.: A review of isolated compounds and biological activities

“…Many reported constituents are sesquiterpene in character (Ober et al, 1985b(Ober et al, , c, d, 1984a(Ober et al, , 1984b(Ober et al, , 1984cOhguchi et al, 2009;Carvalho et al, 2014;Martinez et al, 1987b;Bohlmann et al, 1984Bohlmann et al, , 1982f, e, d, c, b, a, 1981bFischer et al, 1984;Lee et al, 1982aLee et al, , 1982bVichnewski et al, 1982;Quijano et al, 1979;Herz and Kumar, 1980;Bohlmann and Jakupovic, 1979;Bohlmann and Zdero, 1977b). Also documented are essential oils (Carvalho et al, 2014), chromenes, chromanones and flavonoids (Lima et al, 2015a, b;Nascimento and Oliveira, 2014;Nascimento et al, 2007a;Ober et al, 1985b;Steinbeck et al, 1997) (Table 1).…”

The genus Calea L.: A review on traditional uses, phytochemistry, and biological activities

“…sp., C. pilosa, C. urticifolia Romo, de Vivar, and Ortega (1973); Bohlmann, Fritz, et al (1981); ; Bohlmann and Jakupovic (1979) 2 11,13-Dihydroxy-calaxin C. pinnatifida Lima et al (2017) 3 9α-Hydroxy-11,13-dihydro-11α,13-epoxyatripliciolide-8β-O-methylacrylate C. crocinervosa, C. zacatechichi, C. pilosa, C. nelsonni, C. ternifolia Bohlmann, Fritz, et al (1981); Lee, Fronczek, Malcolm, Fischer, and Urbatsch (1982); Fischer, Lee, Fronczek, Chiari, and Urbatsch (1984); ; Martinez et al (1988); Ortega et al (1989) 120 Subcortalide C C. subcordata Ober, Fronczek, and Fischer (1984b) 121 Trichomatolide A C. trichomata ; Ober et al (1984) 122 Trichomatolide B C. trichomata Ober et al (1984) 123 Trichomatolide D C. trichomata Ober et al (1984) 124 Trichomatolide E C. trichomata Ober et al (1984) 125 8β-Tyglinoyloxyreynosin C. trichomata, ; Ober et al (1984) 126 (2015) 193 α-Hydroxy-butein C. uniflora 194 Yomogi alcohol…”