The present invention provides compounds of Formula (see Formula) wherein L is selected from the group consisting of -CH2NHCH2-, -CH2NH-, -NH-, -S-, -S(O)-, -S(O)2-, -O-, -OCH2-, -OCH2CH2O-, -NHSO2NH-, (see Formula) and (see Formula) or a pharmaceutically acceptable salt thereof; a compound of the formula: (see Formula), processes for preparing the compounds and their salts, a pharmaceutical composition and methods for treating patients requiring such treatment.