The present invention relates to new, efficient processes for the preparation of 5-(2-oxazolylalkylthio)-2-azacycloalkanoylaminothiazole compounds of formula I or a pharmaceutically acceptable salt thereof, wherein: R is alkyl, aryl or heteroaryl; R1, R2, R3, R4 and R5 are each independently hydrogen, alkyl, aryl or heteroaryl; R6 and R7 are each independently hydrogen, alkyl, aryl, heteroaryl, halogen, hydroxy or alkoxy; R8 is hydrogen, alkyl, aryl, heteroaryl, CONR9R10, COR11 or COOR12; R9, R10, R11 and R12 are each independently hydrogen, alkyl or aryl; m equals 0 to 5; and n equals 0 to 5, which are novel, potent inhibitors of cyclin dependent kinases (cdks). The present invention further concerns new key intermediate compounds, a quaternary ammonium salt of formula III′ and a 2-oxazolylalkyl derivative of formula IX.