The seriatim Cu(I) activation of 1,1,1′,1′-tetrapinacolborylethane to prospective ring closing

The synthesis and characterization of 1,1,1′1′-tetrapinacolborylethane is conducted to study the functionalization of that densely borylated small molecules through Cu-catalyzed coupling with allyl halides. A second Cu-catalyzed allylic alkylation of the homoallyl triboronate products gave access to mixed dihomoallyl diboronates. The intramolecular concatenated allylic alkylation version produced methylenecyclopentane-1,2-dipinacolboronic ester with 2:1 diastereoselection on the trans-diastereoisomer.