Process and intermediates for the preparation of excitatory amino acid receptor antagonists

A compound of the formula (I) ##STR30## Wherein R.sub.1 is ##STR31## R.sub.11 is CO.sub.2 R.sub.2, CON(R.sub.2).sub.2, CN, CH.sub.2 OH, or protected hydroxymethyl;

• R.sub.2 is independently hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 alkenyl, aryl, and C.sub.7 -C.sub.16 arylalkyl;
• or
• R.sub.3 is hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 alkenyl, CON(R.sub.6).sub.2, SO.sub.2 R.sub.6, COR.sub.6, CO.sub.2 R.sub.6, benzyl, or substituted benzyl having from one to two substituents independently selected from the group consisting of C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.8 cycloalkyl, NO.sub.2, halo, halo(C.sub.1 -C.sub.6)alkyl, C.sub.3 -C.sub.6 alkenyl, C.sub.3 -C.sub.8 cycloalkyl-(C.sub.1 -C.sub.3)alkyl, phenyl, C.sub.5 -C.sub.8 cycloalkenyl, C.sub.5 -C.sub.8 cycloalkenyl-(C.sub.1 -C.sub.3)alkyl, COR.sub.2, C.sub.1 -C.sub.10 alkanoyl, OR.sub.2, and C.sub.7 -C.sub.16 arylalkyl;
• or
• X is ##STR32## R.sub.4 is hydrogen, SO.sub.2 R.sub.7, CO.sub.2 R.sub.7, SiMe.sub.3, or CHO;
• R.sub.5 is silyl, C.sub.1 -C.sub.4 alkyl, or C.sub.1 -C.sub.10 alkanyoyl;
• and
• R.sub.6, and R.sub.7 independently are selected from the group consisting of C.sub.1 -C.sub.6 alkyl, aryl, C.sub.7 -C.sub.16 arylalkyl, and C.sub.3 -C.sub.6 alkenyl;
• or a pharmaceutically acceptable salt thereof.