CA2879270C — Process for improved opioid synthesis

USPTO Abstract

There is disclosed a process for preparing a compound of formula V or a solvate thereof (see formula V) from a compound of formula I or a salt or solvate thereof, the process comprising: (see formula I) (see formula V) (a) oxidizing the compound of formula I; (b) adding an acid H+n X n- to the reaction mixture before, during and/or after the oxidation reaction, wherein the acid H+n X n- is added in an amount of from about 0.51 to about 0.55 molar equivalents per molar equivalent of the compound of formula I;(c) precipitating the compound of formula V; and (d) isolating the precipitate from the reaction mixture, wherein, R1 is -H, -(C1-C7)alkyl, aralkyl, -(C2-C6)alkenyl, - SiR3 3, -(C3- C7)cycloalkyl, -(C1 -C7)alkyl-(C3-C7)cycloalkyl, -(C3 -C7)cycloalkenyl, -(C1-C7)alkyl-(C3 - C7)cycloalkenyl, -CR4 2-O-(C1-C6)alkyl, -C(halo)3, -CH2(halo), -CH(halo)2,- SO2R5, or an O- protecting group;R2 is -H, -CH3, -(C2-C7)alkyl, -(C2-C4)alkenyl, benzyl, -(C1- C7)alkyl-(C3- C7)cycloalkyl, -CN, or an N-protecting group; each R3 is independently selected from aryl, ¨(C1- C6)alkyl and ¨(C1-C6)alkoxy; each R4 is independently selected from ¨H and ¨(C1-C6)alkyl; R5 is -(C6-C14)aryl or ¨(C1-C6)alkyl; X n- is SO4 2-; n is 2; and H+n X n- is H2SO4.