C - Chemistry – Metallurgy – 07 – D
Patent
C - Chemistry, Metallurgy
07
D
260/356, 260/279
C07D 311/68 (2006.01) C07D 311/70 (2006.01) C07D 311/96 (2006.01) C07D 405/04 (2006.01)
Patent
CA 2008940
A process for the preparation of a pure (3S,4R)-isomer of a compound of formula (A): (see above formula) wherein one of R1 and R2 is hydrogen and the other is selected from the class of alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy, alkylhydroxymethyl, nitro, cyano, chloro, trifluoromethyl, alkylsulphinyl, alkylsulphonyl, alkoxysulphinyl, alkoxysulphonyl, alkylcarbonylamino, alkoxycarbonylamino or aminosulphinyl, aminosulphonyl or aminocarbonyl, the amino moiety being optionally substituted by one or two alkyl groups, or alkylsulphinylamino, alkylsulphonyl-amino, alkoxysulphinylamino or alkoxysulphonylamino or ethylenyl terminally substituted by alkylcarbonyl, nitro or cyano, or -C(alkyl)NOH or -C(alkyl)NNH2, the alkyl groups or alkyl moieties of alkyl-containing groups having from 1 to 6 carbon atoms; one of R3 and R4 is hydrogen or alkyl having from 1 to 4 carbon atoms and the other is alkyl having from 1 to 4 carbon atoms, or R3 and R4 together are C2-5 polymethylene; R5 is hydrogen, alkyl having from 1 to 3 carbon atoms or acyl having from 1 to 8 carbon atoms; and n is 1 or 2; in which the pyrrolidonyl or piperidonyl ring is formed by cyclising an appropriate precursor dihydrobenzopyranol compound that has already been resolved to the (3S,4R)-configuration, or a mixture in which the (3S,4R)-configuaration predominates with respect to the (3R,4S)-configuration.
Beecham Group P.l.c.
Borden Ladner Gervais Llp
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