Scheme 7.

Ruthenium- and Selenium-Based Methods for the Near-Exhaustive Oxidation of 87^a

^aReagents and conditions: (a) RuCl₃•xH₂O (3 × 3 mol%), KBrO₃ (2 × 5.0 equiv), CCl₄/MeCN/H₂O (2:2:3), 75 °C, 72 h, 72% 89, 7% 90; (b) SeO₂ (3.5 equiv), diglyme, 110 °C, 3 h, then K₂CO₃ (3.0 equiv), Me₂SO₄ (1.0 equiv), with 4 Å MS (1.0 mass equiv): 55% 91, without 4 Å MS, 43% 91, 15% 92.