Independence from the Sequence of Single-Electron Transfer of Photoredox Process in Redox-Neutral Asymmetric Bond-Forming Reaction

Abstract

A catalytic cycle initiated by the oxidative quenching of the excited photosensitizer (Ir*(ppy)3) is established for the enantioselective coupling between (N-arylamino)methanes and (N-methanesulfonyl)aldimines catalyzed by Ir-based photosensitizer and a chiral (arylamino)phosphonium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate under visible light irradiation. This achievement clearly demonstrates the insensitivity of this redox-neutral asymmetric reaction to the sequence of the key redox events involved in the synergistic catalysis.

Photoredox Catalysis in Organic Chemistry

“…56 The key radical–radical coupling step was rendered asymmetric via the formation of a chiral ion pair consisting of the prochiral radical anion, resulting from single-electron reduction of a N -sulfonylaldimine, and a chiral aminophosphonium ion ( 24 ). Here, chiral ion 24 governs the enantiofacial approach of the oxidatively generated N -aryl α-amino radical.…”

“…Challenging carbon–carbon bond-forming reactions between sterically congested C(sp 3 )–centers can also be achieved using radical–radical coupling platforms. 51,53,54 Indeed, the recent catalytic strategy outlined by Ooi 56 raises the exciting prospect of a general and enantioselective approach to these sterically encumbered systems.…”

Organocatalytic Enantioselective Protonation for Photoreduction of Activated Ketones and Ketimines Induced by Visible Light

“…Based on the absolute configuration of C3 , preferable transition states are proposed for complexes 9 and 10 ; after enantioselective protonation from the Re ‐face of 10 , products 2 were obtained with the observed absolute configuration . C3 would then be regenerated from its conjugate base by the addition of H + ,, indicating its substantial role in H + transfer interchange. The homo‐coupling of the THIQ‐2 .…”

Recent Progress of Chiral Iminophosphorane Catalysis

“…并通过催化剂骨架拉近两个反应物 的距离, 从而提高反应转化率和选择性 [13] . 近年来 此后, Ooi 小组 [16,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][34][35][36][37][38][39][40][41][42][43][44][45][46] 通过类似的策略, 基于手 性氨基酸、手性联萘二胺和手性二苯乙二胺等成熟的二 胺合成子开发了一系列的手性螺环鏻盐(2～5, 图 3), 并 将其作为膦腈碱催化剂的前体用于各种各样的不对称 化学反应中, 取得了丰硕的成果. 3a, R 1 = R 2 = R 3 = Me, Ar = 4-ClC 6 H 4 X = Cl; 3b, R 1 = R 2 = R 3 = Me, Ar = Ph; 3c, R 1 = Me, R 2 = Et, R 3 = Me, Ar = Ph; 3d, R 1 = R 2 = R 3 = Me, Ar = Ph, X = t BuCO 2 ; 3e, R 1 = H, R 2 = i Pr, R 3 = Me, Ar = 4-FC 6 H 4 ; 3f, R 1 = H, R 2 = Pr, R 3 = Me, Ar = 3-MeC 6 H 4 ; 3g, R 1 = Me, R 2 = Et, R 3 = Me, Ar = Ph; 3h, R 1 = Me, R 2 = Et, R 3 = Et Ar = Ph; 3i, R 1 = Me, R 2 = Et, R 3 = Me, Ar = 3,5-Cl 2 C 6 H 3 ; 3j, R 1 = Me, R 2 = Et, R 3 = Me, Ar = 3-FC 6 H 4 ; 3k, R 1 = R 2 = -(CH 2 ) 5 -, R 3 [20][21] .…”