New amidino-benzimidazolyl derivatives of tylosin and desmycosin.

New amidino-benzimidazolyl derivatives of antibiotics tylosin and desmycosin are prepared in the reaction of corresponding amidino-substituted o-phenylendiamine with tylosin respectively desmyicosin on the 20-C aldehyde group. The reaction was carried out in absolute ethanol in the presence ofp-benzoquinone. On this way are prepared: 20-[5-(N-isopropylamidino)-2-benzimidazolyl]tylosin hydrochloride 9, 20-[5-(2-imidazolinyl)-2-benzimidazolyl]tylosin hydrochloride 10, 20-[5-(N-morpholinylamidino)-2-benzimidazolyl]tylosin hydrochloride 11, 20-[5-(N-isopropylamidino)-2-benzimidazolyl]desmycosin hydrochloride 12, 20-[5-(2-imidazolinyl)-2-benzimidazolyl]desmycosin hydrochloride 13, 20-[5-(N-morpholinylamidino)-2-benzimidazolyl]desmycosin hydrochloride 14. Their antimicrobial activity was tested on a series of microorganisms.