Process

A compound of the formula ##STR44## wherein R'.sub.1 is selected from the group consisting of alkyl, alkenyl, alkynyl and alkylthio of up to 10 carbon atoms and cycloalkyl of 3 to 7 carbon atoms, all optionally substituted, R'.sub.2 and R'.sub.3 are individually selected from the group consisting of:

• a) hydrogen, halogen, --OH, --SH, acyl of an organic carboxylic acid of 1 to 7 carbon atoms, --CN, free, salified or esterified carboxy and --PO.sub.3 (R).sub.2,
• b) --(CH.sub.2).sub.m1 --(SO).sub.m2 --X--R.sub.10,
• c) alkyl, alkenyl, alkoxy and optionally oxidized alkylthio of up to 6 carbon atoms optionally interrupted by at least one --O--, --S-- or nitrogen and optionally substituted,
• d) optionally substituted phenyl, benzoyl and optionally oxidized phenylthio,
• e) ##STR45## f) --S--S--R.sub.12, R is hydrogen or optionally substituted alkyl or phenyl, m.sub.1 is an integer from 0 to 4, m.sub.2 is an integer from 0 to 2, X is selected from the group consisting of a single bond, --NH--, --NHCO--, --NH--COO--, --N.dbd.CH--N--R.sub.13 and --NHCONH--, R.sub.10 and R.sub.13 are individually selected from the group consisting of hydrogen, alkyl and alkenyl of up to 6 carbon atoms, cycloalkyl of 3 to 6 carbon atoms, optionally substituted phenyl and benzyl, pyridyl, nitropyridyl, pyrimidyl, tetrazolyl, diazolyl, piperidinyl, alkylpiperidinyl, thiazolyl, alkylthiazolyl, tetrahydrofuranyl and methyltetrahydrofuranyl;
• R.sub.6 and R.sub.7 or R.sub.8 and R.sub.9 are individually selected from the group consisting of hydrogen, amino acids, optionally substituted alkyl and alkenyl of up to 6 carbon atoms, optionally substituted phenyl, benzyl and phenethyl and --(CH.sub.2).sub.m1 --S(O).sub.m2 --X--R.sub.10 or R.sub.6 and R.sub.7 or R.sub.8 and R.sub.9 taken together with the nitrogen to which they are attached form a monocyclic ring of 5 to 7 ring members or condensed rings of 8 to 14 ring members, both optionally containing at least one heteroatom of the group consisting of --O--, --S-- and nitrogen and optionally substituted with at least one member of the group consisting of halogen, --OH, --NO.sub.2, alkyl and alkoxy of 1 to 6 carbon atoms, --NH.sub.2, mono and dialkylamino of 1 to 6 carbon atoms and phenyl or R.sub.8 and R.sub.9 are individually acyl of an organic carboxylic acid of 1 to 6 carbon atoms or one of R.sub.8 and R.sub.9 is carbamoyl, alkoxycarbonyl or benzyloxycarbonyl or R.sub.8 and R.sub.9 together with the nitrogen form phthalimido or succinimido, R.sub.12 has the definitions of R.sub.2 and R.sub.3 except for amino or alkoxy with the proviso at least one of R.sub.2 and R.sub.3 is an optionally substituted alkoxy or --(CH.sub.2).sub.m1 --S(O).sub.m2 --X--R.sub.10, B is boron and X.sub.1 and X.sub.2 are such that:
• either X.sub.1 and X.sub.2 are individually selected from the group consisting of hydroxyl, alkyl and alkoxy of 1 to 6 carbon atoms, phenyl and phenoxy, or X.sub.1 with X.sub.2 form with the boron atom to which they are linked a ring selected from the group consisting of ##STR46## X.sub.3 is hydrogen or alkyl of 1 to 4 carbon atoms and X.sub.4 is halogen, alkoxy, triflate or --O--SO.sub.2 F with the reactive groups optionally protected.