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A novel Lewis acid catalyzed formalintramolecular [3 + 3] cross-cycloaddition(IMCC) of cyclopropane 1,1-diesters has been successfully developed.This supplies an efficient and conceptually new strategy for constructionof bridged bicyclo[2.2.2]octane skeletons. This [3 + 3]IMCC couldbe run up to gram scale and from easily prepared starting materials.This [3 + 3]IMCC, together with our previously reported [3 + 2]IMCCstrategy, can afford either the bicyclo[2.2.2]octane or bicyclo[3.2.1]octaneskeletons from the similar starting materials by regulating the substituentson vinyl group. [ABSTRACT FROM AUTHOR]

A tandem isomerization/intramolecular[3 + 2] cross-cycloaddition(IMCC) of cyclopropane 1,1-diesters with α,β-unsaturatedketones/aldehydes under a cooperative catalysis of photo and Lewisacids has been successfully developed. This supplied a general andefficient strategy for construction of medium-sized carbocyclic (8-,9-, and 10-membered) skeletons as well as such carbocycle-based bridgedoxa-bicyclo[n.2.1] (n= 4–6)skeletons. [ABSTRACT FROM AUTHOR]

(-)-Englerin A was synthesized in 20 steps from the commercially available material (R)-(+)-limonene. In addition, (-)-englerin B, (+)-orientalol E/F and (-)-oxyphyllol were obtained from the intermediate in the route. The key steps include a hydroxyl-directing stereoselective and regioselective intramolecular cyclopropanation and a multi-gram-scale stereoselective formal intramolecular [3 + 2] cross cycloaddition ([3 + 2]-IMCC) of a cyclopropane 1,1-diester with a carbonyl. A precursor of 7,10-diastereoisomer of englerins was also obtained. [ABSTRACT FROM AUTHOR]