ADO.Net in Asp.Net 5 -

when use connection string builder in asp.net 5 application error:

error cs0012 type 'dbconnectionstringbuilder' defined in assembly not referenced. must add reference assembly 'system.data, version=4.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089'.

i'm using dnx451 framework, sugestions?

example project.json

"frameworks": {         "dnx451": {             "frameworkassemblies": {                 "system.data": "4.0.0.0"             }         },         "dnxcore50": {             "dependencies": {                 "system.data.sqlclient": "4.0.0-beta-*"             }         }     }