Science of Synthesis

Andrus, M. B., Science of Synthesis: Stereoselective Synthesis, (2011) 3, 480.

Various metal catalysts based on bismuth,[‌51‌] chromium,[‌52‌] rhodium,[‌53‌] iron,[‌54‌] and ruthenium,[‌55‌] in conjunction with tert-butyl hydroperoxide, have been employed to convert alkylbenzene derivatives into the corresponding carbonyl-containing aryl species. For example, catalytic bismuth(0), picolinic acid (pyridine-2-carboxylic acid), and tert-butyl hydroperoxide have been used in a convenient, regioselective oxidation of a benzopyran at the benzyl ether position to give the benzopyranone ‌20‌ in high yield (‌Scheme 7‌).[‌51‌] A series of versatile oxidation methods that utilize 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide (2-iodylbenzoic acid, IBX) have also been reported. In particular, the oxidation of sensitive 1-(allyloxy)-2-methylbenzene with excess 2-iodylbenzoic acid in hot dimethyl sulfoxide selectively generates 2-(allyloxy)benzaldehyde (‌21‌) in very good yield (‌Scheme 7‌).[‌56‌]

‌Meeeee 8‌ Meee Meeeeeeee eee Meeeeeee ee Meeeeeee Meeeeeeee[‌88‌,‌88‌]

Meeeeeeeeeee Meeeeeeee

8-(Meeeeeee)eeeeeeeeeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

8-Meeeeeeeeeee eeee (888 ee, 8.8 eeee) eee eeeee ee e eeee ee 8-(eeeeeeee)-8-eeeeeeeeeeeee (888 ee, 8.8 eeee) ee eeeeeeeeeeeee/MMMM (8:8; 8.8 eM) eee eee eeeeeee eee eeeeee ee 88 °M eee 88 e. Mee eeeeeee eee eeee eeeeee ee ee, eeeeeee eeee Me8M, eeeeee eeee 8% MeMMM8 (8 × 88 eM), M8M (8 × 88 eM), eee eeeee (88 eM), eee eeee eeeee (MeMM8). Meeeeeeeeeee (eeeeee eee, eeeeee/Me8M 88:8 ee 8:8) eeeeeeeee eee eeeeeee; eeeee: 888 ee (88%) ee eeeeeeee ee eeeeeeeee eeeeeeee eeeeeeee; eeeee: 88 ee (88%).

References