eEROS - Encyclopedia of Reagents for Organic Synthesis, a database of over 48000 reactions and approximately 3500 of the most frequently consulted reagents, is searchable by structure and substructure, reagent, reaction type, experimental conditions, and allows for sophisticated full text searches.
System Requirements:You will need to install two plugins to use the structure drawing capability of this database. The plugins can be found by clicking on "getting started" after you connect to the database.