本發明係有關於一種如下式(I)之化合物: 其中R1 、R2 、R3 及A如說明書所定義。本發明亦揭露(1)一種醫藥組成物,其包括該化合物,以及(2)一種治療大麻素受體相關疾病之方法,其係使用該化合物。The present invention relates to a compound of formula (I): in which A, R1 , R2 , and R3 are defined the same as the specification. Also disclosed are (1) a pharmaceutical composition containing such a compound, and (2) a method for treating a cannabinoid receptor-mediated disorder using such a compound.