Triplet-triplet annihilation (TTA) mediated NIR-to-vis photon upconversion (UC) operating under incoherent and low power excitation is increasingly attractive for various applications including photovoltaics. Unfortunately, efficient TTA emitters/annihilators for this spectral...

Rapid access to both enantiomers of vellosimine and its derivatives is secured from a readily affordable C 2 -symmetric 9azabicyclo[3.3.1]nonane precursor available in both enantiomeric forms. The strategy reported leverages desymmetrization via intramolecular cyclization used to assemble the key intermediate with two differentiated carbonyl groups. Late-stage site selective indolization enables a concise synthesis of vellosimines and a straightforward diversification of the alkaloid scaffold.