Of -specionin

Activattd dimethyl sulfoxide oxidations have been fairly well used in the synthesis of monoterpenes, as seen in the oxidation to an aldehyde of the alcohols (40), en route to loganin aglycone, and (41), a precursor in a synthesis of specionin (equation 16). ... 

The asymmetric glyoxylate-ene reactions have been exploited in the total synthesis of (—)-specionin, which involves asymmetric desymmetrization of a prochiral diene (eq 3), and (—)-xylomollin, which involves an efficient kinetic resolution of a racemic diene (eq4).i - ... 

The fluoride-mediated rearrangement of the enol ether terminated vinylcyclopropane 16 to tricyclic ketones 17 and 18 has been featured in a recent synthesis of specionin. Another direction of reaction, a Cope rearrangement, has also been observed in the fert-butyldimethyl-silyl enolates 19 of ketones of type 16. ... 

Vandewalle et al. have also used oxidative ring opening of one side of a norbomanone to prepare a number of iridoids, culminating in a synthesis and correction of the structure of specionin. At first they described the synthesis of teucrium lactone (425) and a loganin precursor (472) from the Diels-Alder adduct 473 of cyclopentadiene and methyl ( )-crotonate (Scheme 44). The same paper describes the preparation of the all-enafo-isomer 474 of ketone 475, from... 

This approach was then extended to the synthesis of structure 480 (Scheme 45), a compound believed to represent the structure of specionin, an insect antifeedant isolated from the leaves of Catalpa speciosa, Warder. It turned out that 480 was not identical to specionin, and after correctly predicting the structure 481," they went on to synthesize it (Scheme 45). °... 

Van der Eye ken E, De Bruyn A, Van der Eycken J, Gallant P, Vandewalle M 1986 Iridoids The structure elucidation of specionin based on chemical evidence and NMR analysis. Tetrahedron... 

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