Alkaloid synthesis: indolizidines with ease

The vast majority of methodology papers on hydroboration demonstrate utility through a hydroborationoxidation sequence that ultimately delivers an alcohol product. This is driven by ease of handling of alcohols, compared with alkylboranes, and allows easy comparison with previously described methodology. The carbonboron bond that is initially formed is, however, highly versatile, and the boron can easily be replaced by a proton, a halogen, a nitrogen-containing group or an alkyl chain, in addition to the commonly used hydroxyl, all with excellent stereochemical control.