The Solandelactones A-H have been synthesized via a short convergent approach utilizing common building blocks. Based on the diastereoselectivity of the crucial final addition step and on the comparison of prominent NMR data, a structural revision was necessary.

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Abstract:The kinetic enzymatic resolution of various cyclopropane derivatives was systematically investigated. The study focused on synthetically useful cyclopropylmethanols (e.g., 18a/j or 19a/j) as well as some rarely investigated cyclopropanols (e.g., 24/25 or 27). The combination of enantioselective catalytic or diastereoselective synthesis of enantiomerically enriched compounds with enzymatic approaches ultimately led to the most convenient route to enantiomerically pure starting materials. Again, this was especially proven for the synthesis of cyclopropanols 18a/j and 19a/j. Key to the successful investigation was to rigorously establish an analytical tool for the analysis of enantiomeric composition of reaction mixtures.

After providing the marine oxylipins constanolactones A and B, the next two members of this family were synthesized for the first time. Key to the success was a highly enantioselective and Zselective reagent-controlled allyl addition (>99%) en route to the aliphatic side chain.

New total syntheses of the marine oxylipins halicholactone and neohalicholactone are presented. The key building blocks were synthesized utilizing chemoenzymatic methods.