Scheme 5. Substrate scope for catalytic deprotection with desyl as the protecting group. Conditions: 4 (0.4 mmol), AIBN (0.04 mmol), 1a (0.08 mmol), HBpin (0.48 mmol) in toluene (1.0 mL). Isolated yields were given. [a] 0.96 mmol of HBpin was used.