Abstract
The synthesis of the stellettins, differing in the side chain at the C-13 position of the tricyclic region, was attempted by attaching the C-ring to a Wieland-Miescher ketone core using 1,3-bisphosphonoacetone. The decalin precursor was prepared in 35% from condensing ethyl acetate with acrolein, and a MnO2 oxidation, but too little material was obtained to cyclize this into the decalin. An alternative route involving a 2-step Robinson annulation of 2-methyl-1,3 cyclohexanedione with ethyl or methyl vinyl ketone and L-phenylalanine catalysis, followed by protecting C-9 carbonyl with acetal, gave 29% and 14% yields respectively.1,3-Bisphosphonoacetone was prepared m a 3-step synthesis from 1,3-dichloroacetone in 6% yield. Selective monocondensation reaction of bisphosphonate with benzaldehydes and cinnamaldehydes were successful m yielding the phosphonoenone products in 31-67% yields. Cyclization of the C-ring usmg the bisphosphonate was modeled using the tosylate of 2,2-dimethyl cyclohexanone. This was prepared in 35% yield using [hydroxy(tosyloxy)iodo]benzene, and the tosylation reaction furthermore was shown to be successful at secondary a-carbonyl but not at tertiary centers. However, the phosphonate substitution reactions suggested that the tosylate is too sterically hindered for encumbering substitution to occur, whereas smaller leaving group such as mesylate or chloride gave the condensation product.
| Date of Award | 2008 |
|---|---|
| Original language | American English |
| Awarding Institution |
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| Supervisor | Edward Treadwell (Supervisor) |
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