Siphonaria baconi

Baconipyrones A-D 155-158 were isolated in 1989 by Faulkner and co-workers from Siphonaria baconi They... 

Manker DC, Faulkner DJ, Stout TJ, Clardy J. The baconipyr-ones-novel polypropionates from the pulmonate Siphonaria-Baconi. J. Org. Chem. 1989 54(22) 5371-5374. 

Ru-catalyzed AROM/CM sequences served as a key step in the total synthesis of baconipyrone C (163, Scheme 24.42), a marine polyketide isolated from Siphonaria baconi The employed Ru carbene [Ru]-VI is generated in situ by treatment of the achiral Ru-PCya complex with Ag-based V-heterocyclic carbene (NHC) and Nal. And then, the [Ru]-VI-catalyzed AROM/RCM of oxabicycle 161 with styrene (8 equiv) afforded the fully substituted pyran 162 in 62% yield and in 88% ee. The additional transformations led to 163 in good overall yield. Although this application of AROM/CM process to 161 was the first and rare example of Ru-catalyzed enantioselective olefin metathesis process, very recently, an application of enantioselective RCM reaction catalyzed by [Ru]-VII to the synthesis of (—)-5-e/>/-citreoviral has been reported by Funk. ... 

Manker, D.C., Faulkner, D.J., Stout, T.J., and Clardy J. (1989) The baconipyrones novel poly-propionates from the puhnonate Siphonaria baconi. J. Org. Chem., 54, 5371-5374. 

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