Catalytic asymmetric ring-opening of cyclopentadiene–heterodienophile cycloadducts with organometallic reagents*
نویسندگان
چکیده
An unprecedented catalytic asymmetric ring-opening of easily accessible 2,3-heterosubstituted norbornenes with hard alkyl metals (R-M), is able to give a practical regioand stereoselective access to hetero-functionalized alkyl cyclopentenes in an enantioenriched form. The copper-catalyzed desymmetrization reaction with trialkylaluminums of sterically hindered and rigid, trior tetracyclic Diels–Alder adducts, easily available by cycloaddition reaction of cyclopentadiene with 4-phenyl-urazole and 2,3-phthalazine-1,4dione, proved to be particularly efficient. Interestingly, the chirality of the amine part of the BINOL-based phosphoramidite is able to impose the absolute stereochemistry of the corresponding adducts.
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