Scheme 6.
Synthesis of N-2 substituted analogsa
aReagents and Conditions: (a) R1-Br, R2-Br or R2-OMs, K2CO3, DMF, 20-80 °C; (b) 1-bromoethylbenzene, diethyl 2-bromo-2-methylmalonate, K2CO3, DMF, 20-50 °C; (c) NaBH4, Br2, dimethoxyethane, −20 °C to RT; (d) nBuLi, Ts-Cl, THF, −78 °C to RT; (e) nBuLi, THF, 0-80 °C.