Scheme 2
Reagents and conditions: (i) THF, MeOH, NaBH
4
, rt, 4 h, 32%; (ii) Mesyl chloride, DCM, Et
3
N, Et
2
O, -8 °C, overnight, 20%; (iii) CH
3
CN, K
2
CO
3
, EtOH, MW, 120 °C, 100 W, 90 psi, 10 min, 9.3%.