Patent ID: 7906676

Claim:
A process for producing a compound of formula 6, which comprises the following steps: (a) preparing a compound of formula 4 by deprotecting a compound of formula 3; (b) preparing a compound of formula 9 by reacting the compound of formula 4 with R 1 OC(═O)OR 3 ; and (c) reacting the compound of formula 9 with NH(R 4 )(R 5 ): wherein, R 1 and R 3 independently represent alkyl group; R 2 independently represents alkyl group, or together with the oxygen atom to which they are attached may form a dioxolane or dioxane; R 4 and R 5 independently represent hydrogen, trialkylsilyl group, arylmethyl group or 1-arylethyl group, and P represents protecting group.