Scheme 2:
General method for the synthesis of 15a–i. Reagents and conditions: (a) benzyl bromide, DMF, rt, 2h; (b) TBSCl, DMAP, CH
2
Cl
2
, rt, 4h; (c) PCC, CH
2
Cl
2
, rt, 3h; (d) 10%HCl, acetone, rt, 2h; (e) 10a-i, EDCI, DMAP, CH
2
Cl
2
, rt, 8-12h.
