MVC route constraint that does not match a set of words (with help from http://stackoverflow.com/questions/6277022/regex-not-matching-a-list-of-words)

Constraint for workspaces

/* must come before the default route (if still being used)

allows for routes like .../mycompany/projects/index/1
uses the constraint to make sure system controller names can co-exist with workspace names

*/

routes.MapRoute(
    "Workspace",
    "{workspace}/{controller}/{action}/{id}",
    new { controller = "Projects", action = "Index", id = String.Empty },
    new { workspace = @"^(?!.*\bAccount\b)(?!.*\bHome\b).*$" }
);