Cyclododecene isomeric separation by (supported) rhodium(i)-catalysed selective dehydrogenative borylation reaction

Abstract

Cyclododecene, commercially available as a cis/trans mixture, reacts with dipinacolborane (BPin)2 only through the cis isomer, during the Rh(i)-XantPhos-catalyzed dehydrogenative monoborylation reaction, leaving the starting trans-cyclododecene untouched. In this way, both diastereoisomers can now be easily separated. The catalytic Rh(i)-phosphine complex progressively degrades under the reaction conditions; thus we also present here a cheap, ligandless Rh(i)-supported zeolite NaY catalyst, equally selective for the dehydrogenative monoborylation reaction. These results provide a new methodology for macrocyclic alkene diastereoisomeric separation.