Scheme 2. Synthesis Routes of Compounds 6v and 8a-8ba.
aReagents and conditions: (i) MeI, NaH, DMF, 0 °C~RT, 2h, 73%; (ii) Hydrazinium hydroxide, Acetic acid, MeOH, RT, overnight, 91%; (iii) (a) 3-methylbenzo[d]thiazole-2(3H)-thione or 3-methylbenzo[d]oxazole-2(3H)-thione, TfOMe, DCM, 0 °C~RT, 2h; (b) 7, TEA, EtOH, 80 °C, 5h, 52~61%, two steps.