利托那韦中间体/ N-[N-甲基-N-((2-异丙基-4-噻唑基)甲基)氨基)羰基]-L-缬氨酸锂盐Methyl (4,6-diamino-2-(1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl)pyrimidin-5-yl)carbamate