Facile and Enantiospecific Syntheses of (6S,7R)-6-Chloro-7-benzyloxy-, (7S)-Halo-, and (7S)-Hydroxy-cocaine and Natural (−)-Cocaine from d-(−)-Ribose

First syntheses of C6,7 and C7 enantiopure cocaine analogues were achieved from d-(−)-ribose via a trans-acetonide controlled endo-selective intramolecular nitrone-alkene cycloaddition (INAC) as the key step. This synthetic scheme allows practical preparation of cocaine analogues for bioevaluation as potential candidates for the treatment of cocaine addiction and as potential conjugates for immunotherapy.