Process for the preparation of tricyclo-[3.3.1.1.sup.3,7 ]dec-2-yl-[R-(R*,R*)]-3-(1H-indol-3-ylmethyl)-3-methyl-4,9-dioxo-7,11-di phenyl-10-oxa-2,5,8-triazaundecanate

Process for the preparation of tricyclo [3.3.1.1.sup.3,7 ]dec-2-yl-[R-(R*,R*)]-3-(1H-indol-3-ylmethyl)-3-methyl-4,9-dioxo-7,11-diph enyl-10-oxa-2,5,8-triazaundecanate, which consists of hydrogenation of N-[(benzyloxy)-carbonyl]-(R)-.beta.-amino-1-azido-2-phenylethane of formula ##STR5## in ethyl acetate in the presence of a Raney nickel catalyst and reacting VI with gaseous or solid carbon dioxide to form N.sup..beta. -[(benzyloxy)-carbonyl]-(R)-.beta.-amino-2-phenylethylamine carbonate of formula ##STR6## which precipitates out of solution VIII and is reacted directly in stoichiometric amount with N-[(2-adamantyloxy)carbonyl]-.alpha.-methyl-R-tryptophane of the formula ##STR7## dissolved in ethyl acetate and mixed at about 20.degree. C. with 1hydroxy-1H-benztriazole hydrate and dicyclohexylcarboximide to form the final product ##STR8## and converting, if desired, to a pharmaceutically acceptable salt.