Disclosed is a compound of Formula (I), in which R1, R2, R3, R4, R5, R6, X,and a are defined herein, or a pharma-ceuticallyacceptable salt thereof. Also disclosed are a pharmaceutical compositioncomprising a compound or salt therof of For-mula (I)and a method of treating a disease which benefits from the modulation of thevitamin D receptor, such as a bone disorder,cardiovascular disease, a cardiovascular complication associated with renaldisease, endothelial dysfunction, hyperparathyroidism,hypocalcemia, an immune disorder, left ventricular hypertrophy, aproliferative disease, proteinuria, renal disease, and thrombosis.
