The present invention relates to a process for the preparation of (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl (1S,2R)-3-[[(4-aminophenyl)sulfonyl](isobutyl) amino]-1-benzyl-2-hydroxypropylcarbamate as well as intermediates for use in said process. More in particular the invention relates to processes for the preparation of (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl (1S,2R)-3-[[(4-aminophenyl) sulfonyl](isobutyl)amino]-1-benzyl-2-hydroxypropylcarbamate which make use of 4-amino-N-((2R,3S)-3-amino-2-hydroxy-4-phenylbutyl)-N-(isobutyl)be- nzene sulfonamide intermediate, and to processes amenable to industrial scaling up. (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl (1S,2R)-3-[[(4-aminophenyl)sulfonyl](isobutyl) amino]-1-benzyl-2-hydroxypropylcarbamate is particularly useful as HIV protease inhibitors.