Configurations derived from prostaglandin

Tabulated compilations of the chemical shifts of the protons in oxiranes are frequently found in the literature, " but structural conclusions are rarely drawn from the chemical shifts as the coupling constant is a more exact means of establishing the configuration. Configurations and conformations of oxiranes derived from prostaglandin intermediates have been determined from H shifts with the aid of the ring current model. ... 

In our last look at prostaglandins, we can see this put to use in an approach to some prostaglandin derivatives. The plan was to construct PG derivatives from an intermediate of type 216. This j8-ketoester was to be derived from a Dieckmann condensation (construction of the C9-C10 bond). The Dieckmann precursor was to be derived from the reaction of malonate 215 with geminally activated cyclopropane 214. Note that control of absolute stereochemistry in this route leads back to 209, which was resolved as its brucine salt. It is also notable that 214 reacts selectively with malonate 215 at the more hindered secondary (but allylic) carbon of the cyclopropane with clean inversion of configuration. 

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