The invention provides novel compounds having the general formula: wherein R1, R2, R3, R4, R5, R6, X, Y, W and n are as described herein, compositions including the compounds and methods of using the compounds.本發明提供具有以下通式之新穎化合物:其中R1、R2、R3、R4、R5、R6、X、Y、W及n係如本文所闡述:包括該等化合物之組合物及使用該等化合物之方法。