Reactions of diarylbromonium salts with sodium alkoxides

Hypervalent Aryl-, Alkynyl-, and Alkenyl-λ³-bromanes

“…21 The same holds true for the reactions of diaryl-l 3 -bromanes (Scheme 7): phenyl ether 8a and nitrobenzene 8b were formed three times faster than the 4-substituted products 9a and 9b, respectively. 13,14 Of the two possible transition states leading to the formation of 8a and 9a, in which the nucleophilic heteroatom ligand, the OEt group, in the l 3 -bromane 7a has an interaction with an ipso carbon atom of the aryl groups, 8aa is more favorable than 9aa, because both the negative charge on the aromatic ring and the enhanced positive charge on bromine(III) are more effectively stabilized by the substituents. These polarized transition states account for the preferred coupling of nucleophiles with the more electron-deficient aryl group.…”

“…Diphenyl-l 3 -bromane 4 serves as a more efficient phenylation agent for alkoxide anions than diphenyliodane 6 (Scheme 5). 13 Reaction of the bromane 4 with sodium ethoxide in ethanol under heating afforded phenyl ethyl ether in a high yield, while use of the iodane 6 gave only a 14% yield of the ether with benzene (68%) being obtained as the major product. In these reactions, benzene arises through a free-radical process involving the formation of phenyl radical, probably produced via a single- electron transfer (SET) from the alkoxide to the l 3 -haloganes.…”

“…The larger deshielding of the a-carbon in l 3 -iodane 16 than that in l 3 -bromane 14a is mostly due to the diminishing spin-orbit effects, probably evoked by partial removal of lone-pair electrons on the iodine upon the change of the oxidation state from univalent to trivalent. 32 On the other hand, a negligibly small increase in the 13 C NMR chemical shift of the a-carbon in l 3 -bromane 14a is in part due to the small heavy-atom effects of bromine compared to iodine.…”

Synthesis, Structure and Application of Aryl Bismuth Compounds

“…Отметим, что в органической химии известны реакции, приводящие к фенилированию гидроксильных групп, например, взаимодействие спиртов с солями дифенилбромония [95] или дифенилиодония [96], протекающее по S N 2-механизму. Однако синтетического значения указанные реакции не получили, очевидно, из-за недостаточно высоких выходов конечных продуктов.…”

ipso‐Nitrierung von Arenen

“…[18] Nesmeyanov, McEwen und Olah et al beschrieben unabhängig voneinander die nucleophile Nitrolyse von Diarylhaloniumionen mit Natriumnitrit. [19][20][21] Nitroarene können außerdem in guten Ausbeuten durch Nitrodediazotierung von aromatischen Diazoniumsalzen in Gegenwart von Kupfer(I) in neutraler oder Schema 1. Palladium-katalysierte regioselektive Umwandlung von Arylchloriden, -triflaten und -nonaflaten zu Nitroarenen.…”