tert-Butyl 4-(1-amino-6,7-dimethoxyisoquinolin-3-yl)piperazine-1-carboxylate is an intermediate for the synthesis of Terazosin-md (T105020), an analog of Terazosin (T105000), which is an α1-adrenergic receptor antagonist alleviating organ damage in studies done on rodent models of stroke and sepsis and has potential to be used for treatment for diseases.