(12S, [13S,] [14S,] [19R,] [20R,] [21R,] 22S)-21- (TERT-BUTYLDIMETHYLSILANYLOXY)-13,19- [BIS- (4-METHOXYBENZYLOXY)-12,] 14,20, 22-tetramethylhexacosa-10,15, 23, 25-TETRAEN-1-(TERT- Butyldimethylsilanyl) -ol