Process for preparing galanthamine derivatives by asymmetric reduction

摘要

PCT No. PCT/GB96/00843 Sec. 371 Date Feb. 2, 1998 Sec. 102(e) Date Feb. 2, 1998 PCT Filed Apr. 4, 1996 PCT Pub. No. WO96/31453 PCT Pub. Date Oct. 10, 1996The subject invention concerns a process for preparing a compound of formula (3) in enantio-enriched form, comprising reducing a compound of formula (4) using an asymmetric enantiospecific reductant, wherein A1=A2=H or A1, A2=O; B1=B2=H or B1, B2=O; Z=H, C1-20 alkyl or a precursor thereof, or a removable protecting group for nitrogen, e.g, acyl or alkyloxycarbonyl; Y=H or a substituent; R1=C1-20 alkyl; and R is an optional, additional substituent.