Table 3. Conditions and yields for silylation of 5c.

Conditions	2′:3′-O-bis-TBDMS	2′-TBDMS (7)	3′-TBDMS
THF–AgNO3–Py	13%	32%	32%
DMF–imidazole	18%	31%	40%
Py–imidazole	8%	29%	29%
Dichloroethane–imidazole	10%	36%	41%