Sanofi SA has divulged substituted pyrrolo[2,3-d]pyrimidines acting as leucine-rich repeat kinase 2 (LRRK2; dardarin and/or G2019S mutant) inhibitors reported to be useful for the treatment of Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, Lewy body dementia, progressive supranuclear palsy, frontotemporal dementia and Niemann-Pick disease.