urea intermediate ( 37 ). This compound then spontaneously undergoes
internal displacement of chlorine to form the desired derivative ( 38 ).
The statine-like aminoalcohol function in this compound differs from
previous examples by the presence of an additional pendant benzyl
group; the supporting carbon chain is of necessity longer by one
member. Condensation of that diamine ( 39 ),^7 protected at one end as its
N,N-dibenzyl derivative, with 2,6-dimethylphenoxyacetic acid ( 40 ) gives
the corresponding amide ( 41 ). Hydrogenolysis then removes the benzyl
protecting groups to afford primary amine 42. Condensation of that with
intermediate 34 affords the HIV protease inhibitor 43.^8
8 OPEN-CHAIN COMPOUNDS