Enantiomerically pure cyclopropylboronic esters: auxiliary- versus substrate-control
作者:Jörg Pietruszka、Andreas Witt
DOI:10.1039/b006970l
日期:——
Stable, enantiomericallypurecyclopropylboronicesters are synthesized from alkynes by a hydroboration–cyclopropanation sequence. The direct hydroboration—utilizing 1,3,2-dioxaborolane 4—is most convenient, however, with more functionalized side-chains it failed to give the desired intermediates. Using the more reactive dicyclohexylborane, followed by oxidation and transesterification, is a good alternative