Rhodium-Catalyzed Stereoselective Intramolecular Tandem Reaction of Vinyloxiranes with Alkynes: Atom- and Step-Economical Synthesis of Multifunctional Mono-, Bi-, and Tricyclic Compounds

Skeletal diversity in diversity-oriented synthesis has proven to be especially challenging. A rhodium-catalyzed intramolecular tandem reaction of vinyloxirane-alkynes leading to four structurally distinct classes of mono-, bi-, and tricyclic carbocycles and heterocycles was developed. [Rh(NBD)(2)]+BF4- is identified to be an efficient catalyst for these transformations. Using this highly efficient catalyst, hetero-[5 + 2] cycloadditions, tandem hetero-[5 + 2] cycloaddition/Claisen rearrangements, and subsequent cyclopropane ring-opening reactions of vinyloxiranes with monoalkynes afford 2,S-dihydrooxepins, tetrasubstituted vinylcyclopropanes, and multifunctional five-membered rings, respectively, under mild conditions with high stereoselectivity and yield. Moreover, hetero-[5 + 2] cycloaddition/Claisen rearrangement/[5 + 2] cycloaddition reactions of vinyloxiranes with diynes for step-economical construction of linearly fused 5-7-5 tricyclic skeletons has also been developed. The complete transfer of chirality from readily available vinyloxiranes to the corresponding products provides a highly efficient and practical access to these chiral cyclic compounds.