Patent ID: 8779150

Claim:
A process for the manufacture of a compound of formula A said process being characterized in that a) a compound of formula B is reacted in the presence of a halogenation reagent, optionally followed by the introduction of amino-protecting groups, to give a compound of formula C b) said compound of formula C is further reacted in the presence of a palladium catalyst, a base and a compound of the formula D to give the compound of formula E and c) the compound of formula E is further treated with an acid to give the compound of formula A; wherein R is phenyl, which is unsubstituted or once or several times substituted by halogen; R 1 , R 2 , R 3 and R 4 are all methyl, or together with the carbon atoms to which they are attached form a phenyl ring; R 5 is —(C1-C6)alkyl or benzyl; X is —Br or —I; and Y 1 and Y 2 are independently selected from the group consisting of benzyl, trifluoroacetyl, acetyl, and hydrogen.