Referring to a compound derived from pirrolo [2,3-d] pyrimidine of formula (i), where a is CH2 or is absent R1 and R2 together with the nitrogen Atom, which are United to form a pirrolidinilo replaced, etc. R3 is Halogen, etc. These compounds are agonists of cannabinoid receptors.Preferred compounds are: 2 - tert - butyl - 7 - [(2-chlorophenyl) methyl] - 4 - (- 3.3 - difluor pyrrolidin-1-yl) pirrolo [2,3-d] pyrimidine Tert Butyl 2 - (7 - [2-chloro-4 - fluorfenil) methyl] - 4 - (difluor 3,3 - (pyrrolidin-1-yl) pirrolo [2,3-d] pyrimidine, among othersReferida a un compuesto derivado de pirrolo[2,3-d]pirimidina de formula (I), donde A es CH2 o esta ausente R1 y R2 junto con el atomo de nitrogeno, al que estan unidos, forman un pirrolidinilo sustituido, etc R3 es halogeno, etc. Dichos compuestos son agonistas de los receptores canabinoides. Son compuestos preferidos: 2-tert-butil-7-[2-clorofenil)metil]-4-(3,3-difluor-pirrolidin-1-il)pirrolo[2,3-d]pirimidina 2-tert-butil-7-[2-cloro-4-fluorfenil)metil]-4-(3,3-difluor-pirrolidin-1-il)pirrolo[2,3-d]pirimidina, entre otros
