Enantioselective Hydrosilylation and Hydrogenation of Alkaloid Precursors

Article abstract of DOI:10.1002/ardp.19883210206

Enantioselective hydrosilylations of the 3,4-dihydropyrrole derivatives 1a-c and 5 with in-situ catalysts consisting of 2 and optically active phosphines yield the N-silyl compounds 2a-c and 6 in up to 66.1percent ee.The N-silyl derivatives were treated with acetic formic anhydride or trifluoroacetic anhydride to give the N-formyl and N-trifluoroacetyl compounds 3a-c, 4a-c, 7, and 8.The alkaloids nicotine and macrostomine were synthesized with 63.3 and 33percent ee by reduction of the N-formyl compounds 8 and 12.Enantioselective hydrogenations of the N-formyl and N-trifluoroacetyl-2-phenylpyrrolines 14 and 15 with the same in-situ catalysts produce the cyclic amides 3a and 4a in up to 36.1percent ee.