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UBC Theses and Dissertations

Synthetic approach to the agelasimines Dotse, Anthony Kwabla


Aside from the structural interest and the success achieved in annulation methods as exemplified in schemes 6 and 7 in this laboratory, synthetic work on the agelasimines A and B and their quartenary 9-methyladenine derivative (44) was encouraged by the presence of a variety of biological activities in these natural products. Another aim of this thesis is to confirm the generality of the synthetic method as applied to the total synthesis of ambliol B (48). Copper(I) mediated conjugate addition of allylmagnesium bromide to 3,4-dimethy1-2-cyclohexen-l-one (63), followed by trapping of the enolate generated with trimethylsilyl chloride, produced the silyl enol ether (62), which was converted to the Mannich base (61). Oxidation of this compound with m-CPBA gave an amine-oxide intermediate which eliminated N , N - dimethylhydroxylamine to give the enone (60). Conjugate addition of the novel vinylgermane cuprate (19) to this enone and treatment of resultant ketone (80) with iodine gave the iodide (59). This iodide was employed as the cyclization precursor to the trans-fused substituted bicyclo[4.4.0]decananol (58). Cyclopropanation of the exocyclic double bond in (58) occurred chemoselectively and gave the cyclopropane (67). The remaining double bond was ozonized and the ozonide cleaved to generate an aldehyde which was reduced to the primary alcohol (93). Hydrogenolysis of the cyclopropane ring of this diol provided the diol (55), which is a possible precursor for the synthesis of the agelasimines A (42), B (43) and their quartenary 9-methyladenine derivative (44). (Abstract contains diagrams)

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