Ionic Transfer Reactions with Cyclohexadiene-Based Surrogates

Abstract

A current research program in our laboratory is devoted to the development of cyclohexa-1,4-diene-based surrogates of difficult-to-handle compounds and their application in metal-free ionic transfer reactions. These investigations grew from our interest in silylium ion chemistry and consequently concentrated initially on surrogates of gaseous and explosive hydrosilanes such as Me3SiH and even monosilane (SiH4). Since then, we have expanded the concept to design surrogates of other species including H2, mineral acids (HI and HBr), and hydrocarbons (isobutane and isobutene). This Account summarizes our discoveries in this area to date, describing the challenges we faced along the way and how we combatted them.1 Introduction2 Transfer Hydrofunctionalization: Variation of the Electrofuge3 Transfer Hydrofunctionalization: Variation of the Nucleofuge4 Transfer Hydrohalogenation Using a Modified Surrogate5 Surrogate Synthesis6 Conclusion

Electron deficient borane-mediated hydride abstraction in amines: stoichiometric and catalytic processes

“…On the other hand, diethyl aniline (12b) formed ammonium hydridoborate ion pair 15 and a mixture of E-and Z-iminium-borate zwitterions 17. Zwitterions 17 are formed as a result of proton transfer from iminium 14b to diethyl aniline (12b) and subsequent addition of enamine 16 to B(C 6 F 5 ) 3 . Further examples of the formation of iminium hydridoborates and subsequent proton transfers are given in Section 2.1.2.…”

“…Grimme, Erker and co-workers performed a combined theoretical and experimental study on the generation and stability of a-ferrocenyl carbenium ions. Hydride abstraction was observed in the reaction of (AE)-dimethylamino- [3]ferrocenophanes (AE)-37a and (AE)-37b with B(C 6 F 5 ) 3 and the ferrocene stabilised iminium hydridoborate salts (AE)-38a and (AE)-38b were formed (Scheme 8). [18][19][20] The iminium moiety in 38a was also hydrolysed to form (AE)-ferrocenophane ketone (AE)-39.…”

“…Scheme 8 B(C 6 F 5 ) 3 -mediated a-amino hydride abstraction from dimethylamino- [3]ferrocenophanes (AE)-37 and resultant reactivity. Scheme 9 B(C 6 F 5 ) 3 -mediated a-amino hydride abstraction from 1,8-bis-(dimethylamino)naphthalene 42 and resultant intramolecular nucleophilic addition.…”

“…This area, pioneered by Oestreich and co-workers, has been recently reviewed. [3][4][5] Iminium ions are valuable molecules that are widely applied in synthetic applications, for example in the Mannich reaction, 6 and are usually formed via the condensation of an amine and a carbonyl derivative. Amines (e.g.…”

Isodesmic C–H Functionalization: Carboxyl-Assisted Remote meta- and ortho-C–H Iodination of Arenes via Shuttle Catalysis

“…The exploration of novel method to cleave and reorganize chemical bonds is the continuous pursuit of organic chemists. [1][2][3][4][5][6] In recent years, significant advances have been achieved in the study of isodesmic reactions, which often use user-friendly reagents and exhibit good functional group tolerance. [7][8][9][10][11][12][13][14] Of particular note, the groups of Morandi 7d and Arndtsen 8 independently reported a functional group metathesis between aryl iodides and aroyl chlorides via a Pd(0)/Pd(II) catalysis (Scheme 1a), 15,16 enabling a mild transfer iodination of aroyl chlorides.…”