addition has been invoked in oxidations of phenolic amides (equation (7)). (7) Substrates containing two phenols (or an aniline and a phenol; see equation (8) below for a related example), undergo oxidative coupling in the presence of hypervalent iodine(III) reagents. Coupling of both the ortho and para positions is possible; however, the use of bulky silyl-protected phenols provides complete selectivity for para coupling. In the example below, coordination of iodine to nitrogen is believed to precede C-C bond formation. (8) Iodonium ylides undergo cycloaddition with alkene acceptors in low yields. In the presence of nucleophiles, substitution of the iodonium group occurs. (9) Reactions with electrophiles yield iodonium salts, which may be quenched in situ by nucleophilic counteranions. In the presence of non-nucleophilic counteranions, the substituted iodonium salts can be isolated. (10) Synthetic Applications Oxidative phenol coupling has been used for the synthesis of alkaloids related to morphine. For instance, the reaction has been employed to transform reticuline derivatives into salutaridine derivatives in a single, presumably biomimetic, step. Yields of reactions of this type tend to be low, however. (11) Comparison with Other Methods Most alternatives to oxidation with hypervalent iodine reagents require the use of environmentally unfriendly metals. However, they may provide comparable or better yields than hypervalent iodine methods. (12) Exposure of phenols to Fremy's salt or cerium(IV) ammonium nitrate also yields quinones. (13) The organic oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) can accomplish many of the same transformations that iodine(III) reagents can, sometimes with higher selectivity. Experimental Conditions and Procedure Typical Conditions Organohypervalent iodine reagents are typically solids that are fairly stable at room temperature and generally insensitive to atmospheric oxygen and moisture. Most reagents have relatively low toxicity and can be handled easily. IBD and IBTA are stable and commercially available, or can be prepared by standard procedures. Iodosobenzene can be prepared by hydrolysis of either (dichloroiodo)benzene or IBD and should be stored in a refrigerator in dark containers. Example Procedure (14) To a stirred solution of p-(3-hydroxypropyl)phenol (152 mg, 1 mmol) and pyridine (0.3 mL) in acetonitrile (10 mL) at 0° was added a solution of IBTA (430 mg, 1 mmol) in acetonitrile (2 mL). The mixture was stirred at room temperature for 10 minutes, diluted with water, and extracted with diethyl ether (3 × 10 mL). The combined organic extracts were washed with saturated aqueous sodium chloride solution, dried (MgSO4), and concentrated in vacuo. The residue was purified