Patent ID: 7767831

Claim:
A process for the manufacture of a compound of the formula III, wherein R is hydrogen, alkyl or alkoxyalkyl; R 1 is hydrogen, alkyl or alkoxyalkyl; R 2 is hydrogen or preferably a hydroxyl protecting group; R 3 is hydrogen or unsubstituted or substituted alkyl; and PG is an amino protecting group, especially one removable by hydrolysis, e.g. lower alkoxycarbonyl, such as tert-butoxycarbonyl or benzyloxycarbonyl; or a salt thereof; said process comprising reacting a compound of the formula I, wherein R, R 1 , R 2 , R 3 and PG are as defined for a compound of the formula III, with a reagent able to transform hydroxy in formula I into X where X is a group other than hydroxy or hydrogen, especially a leaving group, especially a reagent selected from a hydrohalic acid, a thionyl halogenide, PX* 3 , POX* 3 , PX* 5 , POX* 5 wherein X* is a halogennide, a combination of triphenylphosphine and halogen, and an active derivative of an organic sulfonic acid.