Their Preparation and use as pharmaceutically Active compounds. These compounds act as immunomodulatory agents.Claim 1: a compound of the formula (1), where a represents a group of formulas (2), where the asterisks indicate that the Union is United to the Pyridine Group of the formula (1)； r1 represents Cyclopentyl； R2 and R4 represent Methyl or Ethyl represents or Chlorine； R2 represents me Toxi, and R4 represents Chlorine； R3 represents och2cooh och2ch2ch2cooh -, -, - och2conhch2ch2oh,- och2ch2ch2conhch2ch2oh OCH2 -, - NH (CH2) - N - (CH2) M - COOH, - OCH2 - (CH2) n - N (CH3 (CH2) m) - 2 - [(- COOH, azetidin - carboxylic acid - 3 - 1 - il) ethoxy] - 2 - [(Acid 3 Acid) - pyrrolidin-3-yl] - ethoxy - il - 1, 3 - [(azetidin - carboxylic acid - 3 - 1 - il) propoxy] - 3 - [(3 - carboxylic acid - pyrrolidin-3-yl) propoxy] - il - 1 -, - och2ch ( - Oh ch2nh - CH2COOH), och2ch (OH) - - - - ch2nh ch2ch2cooh, och2ch (OH) - ch2n - CH2COOH, (CH3)- och2ch (OH) - ch2n (CH3) - 3 - [(ch2ch2cooh, azetidin - carboxylic acid - 3 - 1 - il) propoxy] - 2 - hydroxy - 2 - hydroxy - 3 - [(pyrrolidin-3-yl - carboxylic acid - 3 - 1 - il) propoxy] - - - (CH2 OCH2 ch2ch2oh) - NH - n, - (CH2) OCH2 - NH - N - (2, - ch CH2OH) OCH2 - (CH2) ch2ch NH - N - (OH) - CH2OH, och2ch (OH) - - - - ch2nh ch2ch2oh, och2ch (CH (OH) - ch2nh CH2OH OCH2) 2 - (CH2) K - NH - CO CH2OH OCH2 -, - NH - N - (CH2) co - CH2COOH, OCH2 - NH - N - (CH2) Co ch2ch2cooh,- och2ch ch2nh (OH) - CO - (CH2) ncooh, OCH2 - (CH2) - N - N (CH3) - CO CH2OH, OCH2 - (CH2) - N - N (CH3) - CO - (CH2 OCH2 CH2COOH) or - N - N (CH3) - CO ch2ch2cooh independently； n represents 1 or 2； M represents, independently, 1, 2 or 3； and K represents 1 or 2； or one of its Salts.Su elaboración y su empleo en forma de compuestos farmacéuticamente activos. Dichos compuestos actúan particularmente como agentes inmunomoduladores.Reivindicación 1: Un compuesto de la fórmula (1), donde A representa un resto del grupo de fórmulas (2), donde los asteriscos indican
