Quassinoids synthetic studies

While it is not clear from these applications whether the Wharton reaction necessarily proceeds via trans diaxial epoxide opening, Ziegler et al in synthetic studies towards quassinoids, have found that there is no such stereoelectronic requirement in a rigid fraws-decalin ring system (Scheme 16). 

Various other synthetic studies on bioactive quassinoids have been described in the literature [122-124], such as synthesis of a picrasane-related intermediate from diterpenes constituents from Cupresaceae species, such as Juniperus communis [125],... 

Fleck TJ, Grieco PA (1992) Synthetic studies on quassinoids total synthesis of ( )-glaucarubolone and ( )-holacanthone. Tetrahedron Lett 33 1813-1816... 

Grieco PA, Collins JL, Moher ED, Fleck TJ, Gross RS (1993) Synthetic studies on quassinoids Total synthesis of (-)-Chaparrinone, (-)-Glaucarubolone, and (-1-)-Glaucarubinone. J Am Chem Soc 115 6078-6093... 

Curcino Vieira IJ, Braz-Filho R (2006) Quassinoids structural diversity, biological activity and synthetic studies. In Atta-ur-Rahman FRS (ed) Bioactive natural products. Elsevier, Amsterdam, p 433... 

Moher ED, Reilly M, Grieco PA, Corbett TH, Valeriote FA (1998) Synthetic studies on quassinoids transformation of (-)-glaucarabolone into (-)-peninsularinone. In vivo antitumor evaluation of (-)-glaucarabolone, (-)-chaparrinone, and (-)-peninsularinone. J Org Chem 63 3508... 

Caruso, A. J., J. Polonsky, and B. Soto Rodriguez Synthetic Studies in the Quassinoid Series. Conversion of Chaparrin into Castelanone and Quassinoid Analogs. Tetrahedron Lett. 23, 2567 (1982). 

More than ten years have elapsed since the publication of a comprehensive review on the quassinoids, the bitter principles of the Simaroubaceae family (80). Interest in these terpenoids has increased enormously in recent years due in part to the finding of the American National Cancer Institute in the early 1970s that these compounds display marked antileukemic activity. Furthermore, a wide spectrum of other biological properties for the quassinoids has been discovered and studies on chemical modifications of inactive members to yield biologically active ones were undertaken. New structures have been established also and numerous synthetic approaches have been developed which include the total synthesis of the parent compound, quassin (p. 250) and also that of castelanolide (p. 253). 

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