| 主权项 |
1. A process for preparing a compound of formula (VI), or a salt thereof, wherein X is H or an alcohol protecting group; and R is H, an optionally substituted C1-C6 alkyl group, or an amino protecting group; comprising double reductive amination reaction of a dicarbonyl compound of formula (VII), wherein X is as defined above, with an amine of formula (VIII), or a salt thereof,
NH2—R (VIII) wherein R is as defined above, in the presence of a reducing agent selected from a borane complex with an amine of formula (IX) or a borane complex with a pyridine of formula (X) wherein each of substituents Y, being the same or different, is H, or an optionally substituted C1-C6 alkyl or aryl group, or two of Y, taken together with the nitrogen atom to which they are linked, form a C5-C6 cycloalkyl ring optionally containing an oxygen atom or an ═NRa group, wherein Ra is hydrogen, an amino protecting group, or a C1-C4 alkyl group; and each of substituents W, being the same or different, is H, an optionally substituted C1-C6 alkyl group, or a halogen atom; and of a solvent, and, if the case, converting a compound of formula (VI) into another compound of formula (VI) or a salt thereof, or converting a salt of a compound of formula (VI) into its free base, or converting a compound of formula (VI) into salt thereof. |
