SciFinder is the most comprehensive chemical information discovery tool. It allows you to explore the CAS databases which contain literature from many scientific disciplines.
CAS Registry: a listing of all compounds published in the chemical literature since 1907
CAplus: a listing of all references in the database. It is where you go to get bibliographic citations and abstracts for papers. The CAPLUS file covers the dates from 1967 to the present. The CAOLD file covers the literature published between 1907 and 1967. Both can be accessed in a number of different ways.
CASREACT: graphical reactions
CHEMCATS: commercial availability
CHEMLIST: regulatory information