The present invention provides novel compounds useful as proteasome inhibitors. The invention also provides pharmaceutical compositions comprising the compounds of the invention and methods of using the compositions in the treatment of various diseases.本發明提供適用作蛋白酶體抑制劑之新穎化合物。本發明亦提供包含本發明之化合物之醫藥組合物,及使用該組合物治療各種疾病之方法。