Scheme 2:
Synthetic route developed for Brs analog
21-23
. Conditions and reagents:
a
. K
2
CO
3
/MeOH, r.t. 6 h, 84.1%.
b.
Ac
2
O/DMAP/py/CH
2
Cl
2
, 2 h, 85.1%.
c.
CuSO
4
/(CH
3)2
CO, r.t. 5 days, 69.2%.
