Process for preparing side chain derivatives of cyclohexapeptidyl lipopeptides

An improved process for the preparation of a cyclopeptidyl amine compound having the formula ##STR19## wherein R.sup.1 is C.sub.9 -C.sub.21 alkyl, C.sub.9 -C.sub.21 alkenyl, C.sub.1 -C.sub.10 alkoxyphenyl, C.sub.1 -C.sub.10 alkoxynaphthyl, or ##STR20## wherein R.sup.a is C.sub.1 -C.sub.10 alkyl;

• or (CH.sub.2)qNR.sup.b R.sup.c wherein R.sup.b and R.sup.c are independently H, C.sub.1 -C.sub.10 alkyl or R.sup.b and R.sup.c taken together with the N atom are ##STR21## wherein R.sup.d is C.sub.1 -C.sub.16 alkyl, phenyl or benzyl;
• p is 1 or 2, and
• q is 2, 3 or 4;
• which comprises
• (a) sequentially reacting a cyclohexapeptide of the formula ##STR22## with a dehydrating agent, a reducing agent and an etherification agent to obtain an aminoalkyl ether derivative of the formula ##STR23## (b) deacylating the ether derivative to obtain a compound of the formula ##STR24## (c) preferentially protecting two of the three amino groups by reaction with a suitable protecting group to afford a compound of the formula ##STR25## (d) reacylating the unprotected amino group by reaction with a suitable activated ester to afford a compound of the formula ##STR26## and (e) deprotecting the protected amino groups to afford a compound of the formula ##STR27##