Nitrenium Ions from Amine‐Iodine(III) Combinations

Abstract

Hypervalent iodine compounds are known for their extensive use as potentialo xidants in organic synthesis.I ns pite of the similar reactivity with transitionm etals,h ypervalent iodine reagents are more preferred because of their environmental sustainability.A mong several types of hypervalent iodine reagents,t rivalent organoiodine(III) reagents are highly popular due to their easy accessibility,s tability and controlled oxidizing reactivity.A lso, iodine(III) reagents are commerciallya vailable andi nexpensive. Amines and amidesr eact with iodine(III) oxidants in some specificw ay to provide ad ivalent electrophilic ionic species known as an itrenium ion. Depending on the nature and stability of the nitrenium ion, numerous oxidative transformations to generate valuable functional molecules have been reported.T his review encompassesd iscussionsa bout hypervalent organo iodine(III)-enabled organic transformationsw ith the involvemento fanitrenium ion as an intermediate. Figure1.Ionic electrophilic speciesw ith 6v alance electrons.

Recent discoveries on the structure of iodine(iii) reagents and their use in cross-nucleophile coupling

“…t Bu + , H + ). 19 Primary anilines on the other hand can be coupled intramolecularly to alkenes as the secondary nucleophiles ( Scheme 6c ). 90 After attack of the double bond onto the umpolung species, the alkyl substituent in intermediate 35 migrates preferentially.…”

Intermolecular C‐Arylation of 2‐Amidobiphenyls Overcoming Intramolecular N‐Arylation

“…The reaction proceeded through nitrenium ion formation followed by intramolecular arylation attack (as shown in Figure 1a). Nitrenium ion is a divalent electron deficient species which could be generated from anilides under hypervalent iodine(III) conditions [4c,6] . Nitrenium ion could also undergo electronic delocalization to build carbenium ion intermediate which are mostly favored in case of sulfonyl protected amines.…”

“…It is expected that the site‐selective intermolecular C−C or C−N coupling reactions could be obtained via orthogonal reaction modulation strategy [13] by the stereoelectronic control on the generated nitrenium ions [4c,14] . Recently, orthogonal strategies [13] are applied in many research field like organic synthesis, [15] organometallic chemistry, [16] supramolecular chemistry [17] mechanochemistry, [18] etc.…”

“…Para‐unsubstituted aminobiphenyl under similar reaction conditions resulted in arylation at C 4 ‐position. We anticipated that the reaction was sterically controlled via carbenium ion intermediate [4c] . This was expected because more stable carbenium might have formed at the para position, as a result of which, the nucleophile 1,3,5‐triethyl benzene underwent intermolecular arylation easily.…”

Synthesis of Oxazoline and Oxazole Derivatives by Hypervalent-Iodine-Mediated Oxidative Cycloaddition Reactions

“…Numerous classes of heterocyclic compounds have been prepared under mild conditions using hypervalent iodine reagents. [50][51][52] In the present review, synthetic approaches to the azole derivatives, oxazolines 1, oxazoles 2, isoxazolines 3, and isoxaz-oles 4 (Figure 1), starting from various substrates using hypervalent iodine species are summarized, and recent developments in chemical and electrochemical synthetic procedures toward these heterocycles are discussed.…”