Metal-free arylation of oxygen nucleophiles with diaryliodonium salts.

Phenols and carboxylic acids are efficiently arylated with diaryliodonium salts. The reaction conditions are mild, metal free, and avoid the use of halogenated solvents, additives, and excess reagents. The products are obtained in good-to-excellent yields after short reaction times. Steric hindrance is very well tolerated, both in the nucleophile and diaryliodonium salt. The scope includes ortho- and halo-substituted products, which are difficult to obtain by metal-catalyzed protocols. Many functional groups are tolerated, including carbonyl groups, heteroatoms, and alkenes. Unsymmetric salts can be chemoselectively utilized to obtain products with hitherto unreported levels of steric congestion. The arylation has been extended to sulfonic acids, which can be converted to sulfonate esters by two different approaches. With recent advances in efficient synthetic procedures for diaryliodonium salts the reagents are now inexpensive and readily available. The iodoarene byproduct formed from the iodonium reagent can be recovered quantitatively and used to regenerate the diaryliodonium salt, which improves the atom economy.

Metal-free synthesis of aryl esters from carboxylic acids and diaryliodonium salts.

An efficient arylation of carboxylic acids with diaryliodonium salts has been developed, giving aryl esters in high yields within short reaction times for both aromatic and aliphatic substrates. The transition-metal-free conditions are compatible with a range of functional groups, and good chemoselectivity is observed with unsymmetric diaryliodonium salts. Furthermore, steric hindrance in the ortho positions is well tolerated both in the carboxylic acid and in the diaryliodonium salt, yielding aryl esters that cannot be obtained via other esterification protocols.

Total synthesis of (+)-korupensamine B via an atropselective intermolecular biaryl coupling.

The asymmetric total synthesis of nonracemic korupensamine B is reported. It includes a newly designed and highly trans-diastereoselective (>20:1 dr) route to the tetrahydroisoquinoline ring and an unprecedented atropdiastereoselective Suzuki-Miyaura coupling for construction of the fully fashioned naphthylisoquinoline framework that invokes π stacking as a possible source of stereocontrol.

Room-temperature Suzuki-Miyaura couplings in water facilitated by nonionic amphiphiles.

Use of a dilute aqueous solution containing a nonionic amphiphile allows efficient Suzuki-Miyaura cross-couplings of arylboronic acids with a wide array of aryl halides and pseudohalides, including sterically hindered and lipophilic substrates, in most cases at room temperature.

Asymmetric 1,4-reductions of hindered beta-substituted cycloalkenones using catalytic SEGPHOS-ligated CuH.

The reagent combination of catalytic amounts of copper hydride ligated by a nonracemic SEGPHOS ligand leads in situ to an extremely reactive species capable of effecting asymmetric hydrosilylations of conjugated cyclic enones in very high ees. An unprecedented substrate-to-ligand ratio as high as 275 000:1 for this transformation has been documented. [reaction: see text]