A process for forming a boronic acid anhydride of a compound of formula ( XIV ): comprising the steps: (A) coupling a trifluoroacetic acid addition salt of a compound of formula (XVIII): with a compound of formula ( XIXa ): wherein the moiety -C(O)X is an activated ester generated in situ by contacting N-(2-pyrazinecarbonyl)-L-phenylalanine with dicyclohexylcarbodiimide and N-hydroxysuccinimide, wherein the moiety C(O)-X is an O-(N-hydroxysuccinimide)ester, to form a compound of formula ( XXIII ): and (B) deprotecting the boronic acid moiety to form a boronic acid anhydride of the compound of formula ( XIV ); wherein the coupling step (A) comprises: (i) providing a solution of (1 R )-( S )-pinanediol 1-ammonium trifluoroacetate-3-methylbutane-1-boronate and N-hydroxysuccinimide, followed by addition of dicyclohexylcarbodiimide to form a suspension; (ii) providing a solution of N-(2-pyrazinecarbonyl)-L-phenylalanine and adding N-methylmorpholine thereto; (iii) adding the solution resulting from step (ii) to the suspension resulting from step (i) and optionally adjusting the resulting suspension to pH 7 by adding N-methylmorpholine; and wherein coupling step (A)(i) comprises providing a solution of (1 R )-( S )-pinanediol 1-ammonium trifluoroacetate-3-methylbutane-1-boronate and N-hydroxysuccinimide in DMF, followed by addition of dicyclohexylcarbodiimide to form a suspension; and/or coupling step (A)(ii) comprises providing a solution of N-(2-pyrazinecarbonyl)-L-phenylalanine in DMF and adding N-methylmorpholine thereto. (A) coupling a trifluoroacetic acid addition salt of a compound of formula (XVIII): with a compound of formula ( XIXa ): wherein the moiety -C(O)X is an activated ester generated in situ by contacting N-(2-pyrazinecarbonyl)-L-phenylalanine with dicyclohexylcarbodiimide and N-hydroxysuccinimide, wherein the moiety C(O)-X is an O-(N-hydroxysuccinimide)ester, to form a compound of formula ( XXIII ): and (B) deprotecting the boronic acid moiety to form a boronic acid anhydride of the compound of formula ( XIV ); wherein the coupling step (A) comprises: (i) providing a solution of (1 R )-( S )-pinanediol 1-ammonium trifluoroacetate-3-methylbutane-1-boronate and N-hydroxysuccinimide, followed by addition of dicyclohexylcarbodiimide to form a suspension; (ii) providing a solution of N-(2-pyrazinecarbonyl)-L-phenylalanine and adding N-methylmorpholine thereto; (iii) adding the solution resulting from step (ii) to the suspension resulting from step (i) and optionally adjusting the resulting suspension to pH 7 by adding N-methylmorpholine; and wherein coupling step (A)(i) comprises providing a solution of (1 R )-( S )-pinanediol 1-ammonium trifluoroacetate-3-methylbutane-1-boronate and N-hydroxysuccinimide in DMF, followed by addition of dicyclohexylcarbodiimide to form a suspension; and/or coupling step (A)(ii) comprises providing a solution of N-(2-pyrazinecarbonyl)-L-phenylalanine in DMF and adding N-methylmorpholine thereto. (i) providing a solution of (1 R )-( S )-pinanediol 1-ammonium trifluoroacetate-3-methylbutane-1-boronate and N-hydroxysuccinimide, followed by addition of dicyclohexylcarbodiimide to form a suspension; (ii) providing a solution of N-(2-pyrazinecarbonyl)-L-phenylalanine and adding N-methylmorpholine thereto; (iii) adding the solution resulting from step (ii) to the suspension resulting from step (i) and optionally adjusting the resulting suspension to pH 7 by adding N-methylmorpholine; and <EOS>