Rapamycin Impurity 59-D4

42-O- (2-Hydroxyethyl-1,1,2,2-d4) rapamycin; (3S,6R,7E,9R,10R,12R,14S,15E,17E,19E,21S,23S,26R,27R,34aS) -9,27-dihydroxy-3- ((R) -1- ((1S,3R,4R) -4- (2-hydroxyethoxy-1,1,2,2-d4) -3-methoxycyclohexyl) propan-2-yl) -10,21-dimethoxy-6,8,12,14,20,26-hexamethyl-9,10,12,13,14,21,22,23,24,25,26,27,32,33,34,34a-hexadecahydro-3H-23,27-epoxypyrido[2,1-c][1]oxa[4]azacyclohentriacontine-1,5,11,28,29 (4H,6H,31H) -pentaone