Diborane as a reducing agent IX [1]: Reduction of a tris(trifluoroacetyl)enaminospiroindoline

Article abstract of DOI:10.1007/BF00807261

Reduction of the title compound (2) with diborane furnishes 1-trifluoroethyl-3-(2′-(trifluoroethylamino)ethyl)-3-vinylindoline (4), 1-hydroxy-trifluoroethyl-3-(2′-(trifluoroethylamino)-ethyl)indole (5), and 1-methyl-2-trifluoroethyl-1,2,3,4-tetrahydro-β-carboline (6). However, treatment of 2 with lithium aluminum hydride, H₂/Pd on charcoal, and sodium borohydride affords hydroxyspiroindolenine 8, hydroxy-bis(trifluoroacetyl)enaminospiroindoline 9, and N-ethyltryptamine 7, respectively. The results are discussed and the mechanisms of the reactions leading to 4-8 are presented.