Scheme 1. Synthetic Route to 6a–h and 7a–h Derivatives.

Reagents and conditions: (i) TosMIC, NaH, 2:1 Et₂O dry/DMSO dry, N₂, room temp, 1 h, 100% yield; (ii) proper arylalkyl halide, DMF, K₂CO₃, 80 °C, overnight, 55–70% yield; (iii) diethyl oxalate, EtONa, THF dry, N₂, room temperature, 2 h, 97–100% yield; (iv) MeOH, NH₂NH₂ dihydrochloride, Et₃N, CH₃COOH gl, room temperature, 2 h, 60–100% yield; (v) THF, NaOH 20%, 90 or 100 °C, 6–12 h, 65–98% yield.