R		R		R
3a	H
3b	o-F	3h	m-F	3n	p-F
3c	o-Cl	3i	m-Cl	3o	p-Cl
3d	o-Br	3j	m-Br	3p	p-Br
3e	o-CH3	3k	m-CH3	3q	p-CH3
3f	o-CN	3l	m-CN	3r	p-CN
3g	o-NO2	3m	m-NO2	3s	p-NO2

Reagents and conditions: (a) Ac₂O, pyridine, reflux, 6 h, 79%; (b) PhSH, imidazole, NMP, 0 °C, 1 h, 70%; (c) R-PhCH₂Br, K₂CO₃, acetone, rt, 3 h; (d) 2M NH₃/MeOH, 0 °C, 1 h, 40%–56% (two steps).