Synergistic Catalysis of Ionic Brønsted Acid and Photosensitizer for a Redox Neutral Asymmetric α-Coupling of <i>N</i>-Arylaminomethanes with Aldimines

Uraguchi, Daisuke; Kinoshita, Natsuko; Kizu, Tomohito; Ooi, Takashi

doi:10.1021/jacs.5b09329

Cited by 302 publications

(139 citation statements)

References 72 publications

Supporting

Mentioning

128

Contrasting

Unclassified

Order By: Relevance

“…Our group 1,39 has routinely used 3 in our standard catalyst screen, and likewise Ooi and coworkers 40 synthesized this catalyst in their asymmetric α-coupling of N -arylaminomethanes and used the photocatalyst in their optimization experiments. 3 is thus included in order to provide electrochemical and photophysical data.…”

Section: Photocatalyst Detailsmentioning

confidence: 99%

Advances in Photocatalysis: A Microreview of Visible Light Mediated Ruthenium and Iridium Catalyzed Organic Transformations

Day

Teegardin

Weaver

et al. 2016

Org. Process Res. Dev.

373

329

View full text Add to dashboard Cite

show abstract

Section: Photocatalyst Detailsmentioning

confidence: 99%

Advances in Photocatalysis: A Microreview of Visible Light Mediated Ruthenium and Iridium Catalyzed Organic Transformations

Day

Teegardin

Weaver

et al. 2016

Org. Process Res. Dev.

373

329

View full text Add to dashboard Cite

show abstract

“…8 However, only one asymmetric approach has been disclosed by Ooi and co-workers (Scheme 1a). 9 In Ooi's work, the addition of a-alkylamine derivatives to N-sulfonylimines to afford diamine derivatives was described. Nonetheless, no examples of visible light photocatalytic reactions with N-sulfinimines exist to the best of our knowledge.…”

mentioning

confidence: 99%

Asymmetric radical alkylation of N-sulfinimines under visible light photocatalytic conditions

et al. 2017

View full text Add to dashboard Cite

In this communication, a new photocatalytic strategy for the addition of alkyl-radical derivatives to N-sulfinimines with complete diastereoselectivity and moderate to good yields is presented. This is the first asymmetric photocatalytic addition to N-sulfinimines under visible light irradiation with smooth conditions and functional group tolerance.Enantiopure sulfinimines, or N-sulfinyl imines, have been used in the asymmetric synthesis of diverse chiral amino derivatives, e.g. a-branched amines, a-and b-amino acids, and a-and b-amino phosphonic acids.1 The N-sulfinyl group is one of the best chiral auxiliaries for imines because the CQN bond is activated for nucleophilic addition, diastereofacial selectivity is provided, and it is easily removable under mild acidic conditions. However, most reactions with N-sulfinimines employ organometallic compounds such as organolithium or Grignard reagents under very restrictive conditions (low temperature and minimal functional group tolerance). In this regard, radical reactions offer a better functional group tolerance under more suitable reaction conditions. However, only a few examples involving radical-mediated intermolecular additions to N-sulfinimines have been reported, 2-4 which are impractical because of the large amount of radical precursors and the use of toxic reagents (Bu 3 SnH). These issues are impeding a simple gateway to valuable chiral amines, and therefore a new straightforward methodology capable of overcoming these limitations is required. On the other hand, visible light photoredox catalysis has received significant attention over the past decade due to its ability to achieve bond constructions that are not possible using established procedures.5 At the same time, photoredox catalysts can also be employed to generate radicals to be used in a diverse range of proven radical strategies. This approach is based on the adeptness transition metal complexes 6 and organic dyes 7 display by engaging in SET processes following photoexcitation with visible light. Numerous photocatalytic examples of racemic radical transformations performed with imines have been published. 8 However, only one asymmetric approach has been disclosed by Ooi and co-workers (Scheme 1a). 9In Ooi's work, the addition of a-alkylamine derivatives to N-sulfonylimines to afford diamine derivatives was described. Nonetheless, no examples of visible light photocatalytic reactions with N-sulfinimines exist to the best of our knowledge. Therefore, our goal is to deliver a novel radical addition to N-sulfinimines, using photocatalysis and visible light irradiation as a viable radical-generating process, and the N-sulfinyl group as a chiral auxiliary to achieve complete stereoselectivity in the synthesis of amine derivatives (Scheme 1b).In order to achieve this goal, we performed an initial study in which the reactivity of the enantiopure N-sulfinimine 1a (R 1 = p-Tol) was tested with different radical donors (see ESI ‡Scheme 1 Previous reaction and present work of this manuscript.

show abstract

“…In 2015, Ooi et al 64 utilized an elegant dual catalytic system comprising a photoredox catalyst and a chiral Brønsted acid to achieve an asymmetric α -coupling of N -sulfonyl imines with N -arylaminomethanes (Scheme 24). Unsymmetrical chiral vicinal diamines were obtained in high yields and excellent enantioselectivities (up to 97% ee) from a wide range of aryl and heteroaryl N -sulfonyl aldimines.…”

Section: Radical-radical Coupling Reactionsmentioning

confidence: 99%

“…The process is initiated by irradiation of Ir III (ppy) 2 (Me 2 phen) + with visible light, followed by a single electron reduction of *Ir III (ppy) 2 (Me 2 phen) + by Ph 2 NMe ( 25.1 ). A SET from Ir II (ppy) 2 (Me 2 phen) ( E 1/2 III/II = −1.58 V vs SCE) 64 to N -sulfonyl imine 25.4 ( E 1/2 red = −1.45 V vs SCE for N -benzylidenemethanesulfonamide) 64 produces α -aminoanion radical 25.5 and regenerates the active photocatalyst. Catalytic ion pair formation between P -spiro chiral tetraaminophosphonium cation 25.6 and 25.5 enables an enantioselective radical coupling reaction between 25.5 and aminomethyl radical 25.3 to afford the desired diamine product 25.7 .…”

Section: Radical-radical Coupling Reactionsmentioning

confidence: 99%

Recent developments in transition-metal photoredox-catalysed reactions of carbonyl derivatives

2017

View full text Add to dashboard Cite

Single-electron reduction of C=O and C=N bonds of aldehydes, ketones, and imines results in the formation of ketyl and α-aminoalkyl anion radicals, respectively. These reactive intermediates are characterized by an altered electronic character with respect to their parent molecules and undergo a diverse range of synthetically useful transformations, which are not available to even-electron species. This Review summarizes the reactions of ketyl and α-aminyl radicals generated from carbonyl derivatives under transition-metal photoredox-catalysed conditions. We primarily focus on recent developments in the field, as well as give a brief overview of catalytic enantioselective transformations that provide means to achieve precise stereocontrol over the reactivity of ion radicals.

show abstract

Synergistic Catalysis of Ionic Brønsted Acid and Photosensitizer for a Redox Neutral Asymmetric α-Coupling of N-Arylaminomethanes with Aldimines

Cited by 302 publications

References 72 publications

Advances in Photocatalysis: A Microreview of Visible Light Mediated Ruthenium and Iridium Catalyzed Organic Transformations

Advances in Photocatalysis: A Microreview of Visible Light Mediated Ruthenium and Iridium Catalyzed Organic Transformations

Asymmetric radical alkylation of N-sulfinimines under visible light photocatalytic conditions

Recent developments in transition-metal photoredox-catalysed reactions of carbonyl derivatives

Contact Info

Product

Resources

About