Sincraian, who won bronze in the men's 85kg event, tested positive for exogenous testosterone at the Rio de Janeiro Games on August 12, according to a statement from sport's highest tribunal.
Aloian, silver medallist in the 52kg boxing event, failed a test for tuaminoheptane, a stimulant.
CAS said the results of both athletes in Rio had been disqualified.
The buildup to the Games was overshadowed by the spectre of doping and about 100 Russian athletes were banned from competing following revelations of a widespread and state-backed doping system in the country.
Image: Russian boxer Misha Aloian
Photograph: Peter Cziborra/Reuters