Biomimetic combination of photoactivation and relay catalysis for an asymmetric cascade reaction

doi:10.21203/rs.3.rs-1747298/v1

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Biomimetic combination of photoactivation and relay catalysis for an asymmetric cascade reaction

https://doi.org/10.21203/rs.3.rs-1747298/v1

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Asymmetric ketene cycloaddition is a powerful tool for chiral heterocycle synthesis, stimulating the development of innovative catalytic strategies to achieve a high level of efficiency and stereocontrol. Herein, we disclose an asymmetric cascade reaction between enynamides and α-diazoketones inspired by natural photosynthesis. The biomimic combination of visible-light photoactivation and relay gold and N-oxide catalysis allowed the facile generation and controlled assembly of two reactive intermediates, ketene and aza-o-quinone methide. This produced chiral bicyclic lactams bearing chiral all-carbon quaternary stereocenters with high efficiency and selectivity. Density functional theory calculations revealed a stepwise [4+2] cycloaddition mechanism, with the stereochemistry controlled by the amide group of the catalyst. Notably, this study presents the first example of chiral N-oxides as catalysts for asymmetric ketene cycloaddition, and demonstrates that a biomimetic cascade strategy is a promising approach to access important chiral heterocyclic scaffolds.

Nature’s biosynthetic machines can rapidly convert simple chemicals into significant complex molecules via the ingenious combination of multiple enzymes in organisms^1-3. An important example is photosynthesis, which is initially driven by solar energy and then catalyzed by a series of special enzymes. Through enzymatic CO₂ fixation, green plants produce C3 compounds, which are further converted to biologically important glucoses under enzymatic catalysis (Fig. 1a)⁴. This biosynthetic process has inspired the development of modern green chemical synthesis^5-10. In particular, the search for efficient biomimetic catalyst systems and cascade reactions continues to be a highly significant and yet challenging issue.

Catalytic asymmetric ketene cycloaddition has been established as a powerful tool for chiral heterocycle synthesis^11-13. Within this realm, asymmetric nucleophilic catalysis using chiral tertiary amines^14-19, nitrogen-heterocyclic carbenes (NHC)^20-21 or phosphines^22-23 is considered an efficient strategy for asymmetric ketene cycloaddition. Despite these notable advances, the development of new chemical transformations through exploitation of new catalytic strategies and catalyst systems remain highly significant. In 2016, we launched a project on chiral heterocycle synthesis through Pd-catalyzed asymmetric ketene cycloaddition^24-28. In this work, inspired by natural photosynthesis and continuing our research interests, we developed the asymmetric cascade reaction of α-diazoketones with enynamides combining visible-light photoactivation and relay gold and organic catalysis (Fig. 1b)^29-31.

The detailed design is depicted in Fig. 2. First, α-diazoketone 2 undergoes Wolff rearrangement^32-35 upon visible-light irradiation to generate ketene int. I in situ (Fig. 2a). Meanwhile, enynamide 1 is activated by the gold catalyst to form aza-o-quinone int. II in situ through intramolecular cyclization according to previous literatures (Fig. 2b)^36-41. Subsequently, the two reactive intermediates, int. I and int. II, undergo enantioselective [4+2] cycloaddition via asymmetric nucleophilic catalysis (Fig. 2c). As chiral nucleophilic catalysts, we chose chiral bifunctional N-oxides, traditionally used as chiral Lewis base catalysts and chiral ligands^42-43, owing to their recent success in asymmetric acyl transfer reactions^44-46.There are two challenges for our design: 1) good catalytic efficiency and high level of stereocontrol with the chiral N-oxide catalysts and 2) compatibility of the Au catalyst with diazo compounds⁴⁷ or alkyne and N-oxide functional groups⁴⁸.Herein, we investigated the viability of our proposed biomimetic strategy through application with a wide range of enynamide and α-diazoketone substrates. Furthermore, we determined the mechanism and origin of stereoselectivity of the final [4+2] cycloaddition reaction through theoretical calculations. The proposed biomimetic strategy is expected to be a facile means of constructing bicyclic lactam scaffolds bearing a chiral all-carbon quaternary stereocenter, which is a well-known challenge in modern synthetic chemistry^49-51.

Condition optimization. We began our study by optimizing the reaction conditions using enynamide 1a and α-diazoketone 2a as the model substrates. To avoid the possible decomposition of diazo compounds and chiral N-oxide catalysts by the Au catalyst, a rational stepwise, one-pot procedure was chosen for this cascade reaction (please see the details on the effects of varying the procedure in Supporting Information). Upon irradiation with 6 W blue light-emitting diodes (LEDs), the designed cascade reaction catalyzed by 5 mol% of cationic gold and 20 mol% of chiral N-oxide OC1 proceeded very well, affording the desired product, 3aa, smoothly (Table 1, entry 1). To further improve the stereoselectivity, other chiral catalysts, OC2-OC4, were examined, although the results were not better than that obtained using OC1 (Table 1, entries 2-4). Routine screening of solvent and temperature were carried out (Table 1, entries 5-11), and the reaction performed in CHCl₃ at -60 °C gave much improved enantio- and diastereoselectivity (Table 1, entry 11: 93% yield, 86% ee, and 15:1 dr). Furthermore, introducing an ethyl group to the 2-position of pyridine in chiral N-oxide catalyst OC1 afforded superior results in terms of both reaction efficiency and stereoselectivity (Table 1, entry 12: 94% yield, 93% ee, and >19:1 dr). The structure of chiral catalyst OC5 and absolute configuration of product 3aa were previously established via single-crystal X-ray diﬀraction analysis. For comparison, several classic chiral tertiary amines, NHC, and phosphine catalysts were also examined, but no better results were not obtained for this asymmetric cascade reaction (please see the details in Supporting Information).

Substrate scope. After establishing the optimized conditions, we examined the generality of this biomimetic cascade reaction. Remarkably, various conjugate enynamides 1 were compatible with the combined photoactivation and relay catalysis system (Table 2). Regardless of the electron-donating and electron- withdrawing substituents on the phenyl group at the alkynyl unit (R¹), enynamides 1a-h smoothly reacted with α-diazoketone 2a, yielding the corresponding chiral annulated furans, 3aa-3ah, in 90-94% yield, 92-95% ee, and >19:1 dr. 2-Naphthyl- (1i) and 3-thienyl-substituted (1j) enynamides were also suitable, affording the corresponding adducts in high yields with high stereoselectivities (3ai: 92% yield, 94% ee, and >19:1 dr; 3aj: 88% yield, 94% ee, and >19:1 dr). In addition to enynamides with aryl or heteroaryl substituents, those with alkyl substituents (i.e., n-Bu, c-hexane, and t-Bu), 1k-m, were also suitable for this combined photoactivation and relay catalysis system, delivering chiral bicyclic lactams 3ak-3am with good results (82-87% yield, 91-95% ee, and 17:1 dr). In parallel, we examined the effect of varying the alkenyl unit in enynamide 1 (R²). A wide range of enynamides bearing electron-donating (3an, 3ao, 3as, and 3at) or electron-withdrawing groups (3ap-3ar) at the para position of the benzene ring were suitable for this transformation (89-94% yield, 90-95% ee, and >19:1 dr). Substitution at the meta position was also tolerated, having no significant eﬀect on the reaction eﬃciency and stereoselectivity (3at: 90% yield, 95% ee, and >19:1 dr; 3au: 93% yield, 90% ee, and >19:1 dr). Enynamides having a 2-naphthyl, 2-thienyl, or cyclohexyl substituent at the alkenyl unit were also suitable and were converted to the corresponding products with good outcome (3av-3ax: 84-93% yield, up to 94% ee and >19:1 dr).

Subsequently, we probed the scope of α-diazoketones 2 for the present transformation. As summarized in Table 3, a variety of α-diazoketones could participate in this biomimetic cascade reaction well. Electronically varied substituents (e.g., Me, Cl, Br, and CO₂Me) at the para position of the benzene ring were compatible, providing chiral products 3ba-3ea in 91-95% yield, 92-98% ee, and >19:1 dr. Varying the substitution position had a minimal effect on the reaction yield and enantio- and diastereoselectivity (3fa–3ia: 85-91% yield, 90-93% ee, and >19:1 dr). Replacement of the methyl group with an ethyl or i-Bu group delivered the corresponding products, 3ja (83% yield, 93% ee, and >19:1 dr) and 3ka (87% yield, 92% ee, and >19:1 dr) successfully. Functional groups at the alkyl side, such as OBn and alkynyl, were also well tolerated in this combined photoactivation and relay catalysis system, delivering highly functionalized bicyclic products 3la and 3ma in 86% yield, 92% ee, and >19:1 dr and 78% yield, 95% ee, and >19:1 dr, respectively.

Synthetic transformation. We then performed a series of experiments to prove the utility of this new methodology using chiral bicyclic lactam 3aa as an example (Fig. 3). First, treatment of 3aa with m-chloroperoxybenzoic acid (m-CPBA) in dichloromethane at 0 °C yielded a new chiral lactam, 4, in 90% yield through a furan epoxidation and ring opening cascade⁵². Interestingly, the oxidative rearrangement of 3aa was observed under similar oxidization conditions followed by base treatment, producing an interesting spirocyclic product, 5, in 81% yield³⁶. Subsequently, the N-tosyl group could be removed by treatment with SmI₂/hexamethylphosphoramide (HMPA) in tetrahydrofuran at -78 °C to give product 6 in 87% yield^53-54. Finally, the amide unit of 3aa could be reduced with LiAlH₄ to give the corresponding amine 7 in 95% yield with the enantiomeric excess of the product retained⁵⁵. Notably, almost no loss of optical purity was observed during all four transformations.

Density functional theory (DFT) calculations. To understand how the chiral N-oxide catalyst, OC5, facilitates the annulation between ketene int. I and aza-o-quinone int. II and to probe the origin of stereoselectivity, DFT calculations at the B3LYP-D3(BJ)/6-311+G(d,p)-SMD(CHCl₃) level were carried out based on the optimal experimental results (see SI for computational details). We first investigated the concerted Diels-Alder-like pathway (path b) depicted in Fig. 2c. However, only the C–C bond was formed at the transition state (see Fig. S4 for the structure of transition state), indicating that the reaction instead proceeds via a stepwise mechanism (path a, Fig. 2c). The molecular orbital analysis showed that the nucleophilic attack of OC5 activates the ketene int. I. Its highest occupied molecular orbital is not only raised in energy, but also polarized with a larger contribution from the p orbital of the tri-substituted C atom, which promotes C–C bond formation (see Fig. S4 for details). The calculated relative free energy profile of the stepwise mechanism is shown in Fig. 4a. Catalyst OC5 first coordinates to int. I via TS0 to generate activated nucleophile int. III which further undergoes Michael addition, and the C–C bond is formed in the resulting intermediate, int. IV. The reaction further progresses through the concerted addition–elimination of the carbonyl group, comprising simultaneous C–N bond formation and C–O bond cleavage, to release the product and catalyst OC5. Interestingly, a hydrogen bond between the sulphonyl O atom of the imine and amide H atom of OC5 was observed during the reaction, hinting at the vital role of the amide group of the catalyst in controlling stereoselectivity. Unlike the pathway leading to the experimentally observed major product with RR configuration, the other three pathways had relatively high-lying transition states in the last step. The difference between the energy barriers of pathways leading to products with different configurations (ΔΔG^‡ = 3.8 kcal/mol between TS0-A and TS2_SS and ΔΔG^‡ = 2.2 kcal/mol between TS0-A and TS2_RS) was in good accordance with the excellent enantioselectivity and diastereoselectivity achieved in the experiments.

Because the origin of stereoselectivity is of primary interest to the mechanistic analysis, further distortion–interaction analysis was performed to shed light on the factors destabilizing the addition–elimination transition states (for detailed distortion–interaction analysis, see Table S6). Given that the products of TS2_RR and TS2_SS were the same in energy, we analyzed these transition states using the same energy reference. As shown in Fig. 4b, OC5 enters a less hindered space to interact with the carbonyl group in TS2_RR, assuggested by the Felkin–Ahn model. On the other hand, it approaches the carbonyl group via a much more congested trajectory in TS2_SS. This causes the elongation of the C–C bonds in the more strained six-membered ring (see Fig. S5 for details), leading to a larger distortion energy of the substrate fragment (ΔΔE_(sub-dist) = 7.1 kcal/mol) and eventually, the increase in energy of TS2_SS. Careful comparison of the geometries of the substrate fragments (Fig. 4c) showed that in TS2_RR, the methyl group points toward the phenyl ring of the sulphonyl group, indicating a C-H–π interaction. In contrast, this weak interaction is absent in TS2_RS, which has a larger substrate distortion energy (ΔΔE_(sub-dist) = 2.7 kcal/mol). In summary, the relatively rigid chiral catalyst, OC5, confines the substrate via O coordination and hydrogen bond to the RR configuration with not only less ring strain, but also weak interaction, which assures good stereoselectivity.

In conclusion, we developed an asymmetric cascade reaction between enynamides and α-diazoketones through the bio-inspired combination of photoactivation and relay catalysis. Particularly, for the first time, chiral N-oxides were identified as efficient catalysts for asymmetric ketene cycloaddition and construction of chiral quaternary stereocenters. The cascade reaction proved to be an efficient approach to synthesize highly functional chiral bicyclic lactams featuring excellent diastereo- and enantioselectivities. We believe that this study presents a new avenue toward molecular complexity construction by learning from nature’s biosynthetic machines.

General procedure. Under argon atmosphere, a flame-dried 10 ml Schlenk tube was charged with Ph₃PAuCl (0.0025 mmol, 1.3 mg, 5 mol%), AgPF₆ (0.0025 mmol, 0.6 mg, 5 mol%) and CHCl₃ (1.0 mL). After stirring at room temperature for 30 min, substrate 1 (0.05 mmol, 1.0 equiv) was added and the resulting mixture was allowed to stir for another 1 h at room temperature. In the meanwhile, α-diazoketone 2 (0.1 mmol, 2.0 equiv) and CHCl₃ (1 mL) were added into another flame-dried 10 ml Schlenk tube equipped with a stir bar and was allowed to stir for 3 h under irradiation of 6 W blue LEDs. The two reaction systems were then mixed by transferring with a micropipette. And another CHCl₃ (1.5 mL) was added into the mixture. The resulting mixture cooled to -60 ℃, after 5 min, the solution of chiral catalyst OC5 (0.01 mmol, 4.6 mg, 20 mol%, in 0.5 mL CHCl₃) was added. After stirring at -60 ℃ for 30 min, the color of reaction mixtures changed from yellow to colorless. The reaction mixture was directly purified by flash chromatography on silica gel to afford the desired product. The enantiomeric excess was determined by HPLC using a chiral column.

Data availability

All the data generated or analysed during this study are included in this article and its Supplementary Information. Crystallographic data have been deposited at the Cambridge Crystallographic Data Centre (CCDC) as CCDC 2155540 (3aa) and CCDC 2155541 (OC5) can be obtained free of charge from the CCDC via www.ccdc.cam.ac.uk/getstructures.

Walji, A. M. D. & MacMillan, W. C. Strategies to bypass the taxol problem. Enantioselective cascade catalysis, a new approach for the efficient construction of molecular complexity. Synlett 1477–1489 (2007).
Garcia-Junceda, E. Multi-step enzyme catalysis: biotransformations and chemoenzymatic synthesis (Wiley, 2008).
Grondal, C. Jeanty, M. & Enders, D. Organocatalytic cascade reactions as a new tool in total synthesis. Nat. Chem. 2, 167–178 (2010).
Govindjee, Photosynthesis Volume I: energy conversion by plants and bacteria (Academic Pr, 1982)
Poupon, E. & Nay, B. Biomimetic organic synthesis (Wiley-VCH, 2011)
Bao, R. Zhang, H. & Tang, Y. Biomimetic synthesis of natural products: a journey to learn, to mimic, and to be better. Acc. Chem. Res. 54, 3720–3733 (2021).
Enders, D. Hüttl, M. R. M. Grondal, C. & Raabe, G. Control of four stereocentres in a triple cascade organocatalytic reaction. Nature 441, 861–863 (2006).
Jones, S. B. Simmons, B. Mastracchio, A. & MacMillan, D. W. C. Collective synthesis of natural products by means of organocascade catalysis. Nature 475, 183–188 (2011).
Qiu, H. Li, M. Jiang, L.-Q. Lv, F.-P. Zan, L. Zhai, C.-W. Doyle, M. P. & Hu, W.-H. Highly enantioselective trapping of zwitterionic intermediates by imines. Nat. Chem. 4, 733–738 (2012).
Zhang, J. Yu, P. Li, S.-Y. Sun, H. Xiang, S.-H. Wang, J. Houk, K. N. & Tan, B. Asymmetric phosphoric acid–catalyzed four-component Ugi reaction. Science 361, 1087 (2018).
Tidwell, T. T. Ketenes II (Willey-VCH, 2006)
Paull, D. H. Weatherwax, A. & Lectka, T. Catalytic, asymmetric reactions of ketenes and ketene enolates. Tetrahedron 65, 6771–6803 (2009).
Allen, A. D. & Tidwell, T. T. Ketenes and other cumulenes as reactive intermediates. Chem. Rev. 113, 7287–7342 (2013).
Taggi, A. E. Hafez, A. M. Wack, H. Young, B. Drury, W. J. & Lectka, T. Catalytic, asymmetric synthesis of β-lactams J. Am. Chem. Soc., 122, 7831–7832 (2000).
Hodous, B. L. & Fu, G. C. Enantioselective staudinger synthesis of β-lactams catalyzed by a planar-chiral nucleophile. J. Am. Chem. Soc. 124, 1578–1579 (2002).
Bekele, T. Shah, M. H. Wolfer, J. Abraham, C. J. Weatherwax, A. & Lectka, T. Catalytic, enantioselective [4 + 2]-cycloadditions of ketene enolates and o-quinones: efficient entry to chiral, α-oxygenated carboxylic acid derivatives. J. Am. Chem. Soc. 128, 1810–1811 (2006).
Wilson, J. E. & Fu, G. C. Asymmetric synthesis of highly substituted β-lactones by nucleophile-catalyzed [2 + 2]cycloadditions of disubstituted ketenes with aldehydes. Angew. Chem. Int. Ed. 43, 6358–6360 (2004).
Xu, X. Wang, K. & Nelson, S. G. Catalytic asymmetric [4 + 2] cycloadditions of ketenes and N-thioacyl imines: alternatives for direct mannichreactions of enolizable imines. J. Am. Chem. Soc. 129, 11690–11691 (2007).
Tiseni, P. S. & Peters, R. Catalytic asymmetric formation ofd-lactones by [4 + 2] cycloadditionof zwitterionic dienolates generated froma,b-unsaturated acidchlorides. Angew. Chem. Int. Ed. 46, 5325–5328 (2007).
Huang, X.-L. He, L. Shao, P.-L. & Ye, S. [4 + 2] Cycloaddition of ketenes with N-benzoyldiazenes catalyzed by N-heterocyclic carbenes. Angew. Chem. Int. Ed. 48, 192–195 (2009).
Chen, X.-Y. Gao, Z.-H. & Ye, S. Bifunctional N-heterocyclic carbenes derived from l-pyroglutamic acid and their applications in enantioselective organocatalysis. Acc. Chem. Res. 53, 690–702 (2020).
Mondal, M. Ibrahim, A. A. Wheeler, K. A. & Kerrigan, N. J. Phosphine-catalyzed asymmetric synthesis of β-lactones from arylketoketenes and aromatic aldehydes. Org. Lett. 12, 1664–1667 (2002).
Ibrahim, A. A. Wei, P.-H. Harzmann, G. D. & Kerrigan, N. J. Josiphos-catalyzed asymmetric homodimerization of ketoketenes. J. Org. Chem. 75, 7901–7904 (2010).
Li, M.-M. Wei, Y. Liu, J. Chen, H.-W. Lu, L.-Q. & Xiao, W.-J. Sequential visible-light photoactivation and palladium catalysis enabling enantioselective [4 + 2] cycloadditions. J. Am. Chem. Soc., 139, 14707–14713 (2017).
Wei, Y. Liu, S. Li, M.-M. Li, Y. Lan, Y. Lu, L.-Q. & Xiao, W.-J. Enantioselective trapping of Pd-containing 1,5-dipoles by photogenerated ketenes: access to 7-membered lactones bearing chiral quaternary stereocenters. J. Am. Chem. Soc. 141, 133–137 (2019).
Zhang, Q.-L. Xiong, Q. Li, M.-M. Xiong, W. Shi, B. Lan, Y. Lu, L.-Q. & Xiao, W.-J. Palladium-catalyzed asymmetric [8 + 2] dipolar cycloadditions of vinyl carbamates and photogenerated ketenes. Angew. Chem. Int. Ed. 59, 14096–14100 (2020).
Li, M.-M. Xiong, Q. Qu, B.-L. Xiao, Y.-Q. Lan, Y. Lu, L.-Q. & Xiao, W.-J. Utilizing vinylcyclopropane reactivity: palladium-catalyzed asymmetric [5 + 2] dipolar cycloadditions. Angew. Chem. Int. Ed. 59, 17429–17434 (2020).
Li, M.-M. Qu, B.-L. Xiao, Y.-Q. Xiao, W.-J. & Lu, L.-Q. Enantioselective trapping of palladium-stabilized oxo-1,4-dipoles with photochemically generated ketenes. Sci. Bull. 66, 1719–1722 (2021).
Hashmi, A. S. K. & Hubbert, C. Gold and organocatalysis combined. Angew. Chem. Int. Ed. 49, 1010–1012 (2010).
Loh, C. C. J. & Enders, D. Merging organocatalysis and gold catalysis—a critical evaluation of the underlying concepts. Chem. Eur. J. 18, 10212–10225 (2012).
Cozzi, P. G. Gualandi, A. Potenti, S. Calogero, F. & Rodeghiero, G. Asymmetric reactions enabled by cooperative enantioselective amino- and Lewis acid catalysis, in asymmetric organocatalysis combined with metal catalysis (Springer, 2020)
Vaske, Y. S. M. Mahoney, M. E. Konopelski, J. P. Rogow, D. L. & McDonald, W. J. Enantiomerically pure trans-β-lactams from α-amino acids via compact fluorescent light (CFL) continuous-flow photolysis. J. Am. Chem. Soc. 132, 11379–11385 (2010).
Bernardim, B. Hardman-Baldwinb, A. M. & Burtoloso, A. C. B. LED lighting as a simple, inexpensive, and sustainable alternative for Wolff rearrangements. RSC Adv. 5, 13311–13314 (2015).
Meng, J. Ding, W.-W. & Han, Z.-Y. Synthesis of chiral esters via asymmetric Wolff rearrangement reaction. Org. Lett. 21, 9801–9805 (2019).
Fan, T. Zhang, Z.-J. Zhang, Y.-C. & Song, J. Construction of all-carbon quaternary stereocenters via sequential photoactivation/isothiourea catalysis. Org. Lett. 21, 7897–7901 (2019).
Zhou, L. Wu, X. Yang, X. Mou, C. Song, R. Yu, S. Chai, H. Pan, L. Jin, Z. & Chi, Y. R. Gold and carbene relay catalytic enantioselective cycloisomerization/cyclization reactions of ynamides and enals. Angew. Chem. Int. Ed. 59, 1557–1561 (2020).
Yang, G. Ke, Y. M. & Zhao, Y. Stereoselective access to polyfunctionalized nine-membered heterocycles by sequential gold and palladium catalysis. Angew. Chem. Int. Ed. 60, 12775–12780 (2021).
Genet, M. Takfaoui, A. Marrot, J. Greck, C. & Moreau, X. Construction of enantioenriched 4,5,6,7-tetrahydrofuro[2,3-b]pyridines through a multicatalytic sequence merging gold and amine catalysis. Adv. Synth. Catal. 363, 4516–4520 (2021).
Yao, T. Zhang, X. & Larock, R. C. AuCl₃-catalyzed synthesis of highly substituted furans from 2-(1-alkynyl)-2-alken-1-ones. J. Am. Chem. Soc. 126, 11164–11165 (2004).
Liu, F. Qian, D. Li, L. Zhao, X. & Zhang, J. Diastereo- and enantioselective gold(I)-catalyzed intermolecular tandem cyclization/[3 + 3]cycloadditions of 2-(1-alkynyl)-2-alken-1-ones with nitrones. Angew. Chem. Int. Ed. 49, 6669–6672 (2010).
Li, Z. Ling, F. Cheng, D. & Ma, C. Pd-catalyzed branching cyclizations of enediyne-imides toward furo[2,3-b]pyridines. Org. Lett. 16, 1822–1825 (2014).
Liu, X. Lin, L. & Feng, X. Chiral N,N′-dioxides: new ligands and organocatalysts for catalytic asymmetric reactions. Acc. Chem. Res. 44, 574–587 (2011).
Liu, X. Zheng, H. Xia, Y. Lin, L. & Feng, X. Asymmetric cycloaddition and cyclization reactions catalyzed by chiral N,N′-dioxide-metal complexes. Acc. Chem. Res. 50, 2621–2631 (2017).
Murray, J. I. Flodén, N. J. Bauer, A. Fessner, N. D. Dunklemann, D. L. Bob-Egbe, O. Rzepa, H. S. Richardson, T. Bürgi, J. & Spivey, A. C. Kinetic resolution of 2-substituted indolines by N-sulfonylation using an atropisomeric 4-DMAP-N-oxide organocatalyst. Angew. Chem. Int. Ed. 56, 5760–5764 (2017).
Xie, M.-S. Zhang, Y.-F. Shan, M. Wu, X.-X. Qu, G.-R. & Guo, H.-M. Chiral DMAP-N -oxides as acyl transfer catalysts: design, synthesis, and application in asymmetric steglich rearrangement. Angew. Chem. Int. Ed. 58, 2839–2843 (2019).
Xie, M.-S. Huang, B. Li, N. Tian, Y. Wu, X.-X. Deng, Y. Qu, G.-R. & Guo, H.-M. Rational design of 2-substituted DMAP-N-oxides as acyl transfer catalysts: dynamic kinetic resolution of azlactones. J. Am. Chem. Soc. 142, 19226–19238 (2020).
Wei, F. Song, C. L. Ma, Y. D. Zhou, L. Tung, C. H. & Xu, Z. H. Gold carbene chemistry from diazo compounds. Sci. Bull. 60, 1479–1492 (2015).
Zheng, Z. Ma, X. Cheng, X. Zhao, K. Gutman, K. Li, T. & Zhang, L. Homogeneous gold-catalyzed oxidation reactions. Chem. Rev. 121, 8979–9038 (2021).
Quasdorf, K. W. & Overman, L. E. Catalytic enantioselective synthesis of quaternary carbon stereocentres. Nature 516, 181–191 (2014).
Liu, Y.-Y. Han, S.-J. Liu, W.-B. & Stoltz, B. M. Catalytic enantioselective construction of quaternary stereocenters: assembly of key building blocks for the synthesis of biologically active molecules. Acc. Chem. Res. 48, 740–751 (2015).
Zeng, X.-P. Cao, Z.-Y. Wang, Y.-H. Zhou, F. & Zhou, J. Catalytic enantioselective desymmetrization reactions to all-carbon quaternary stereocenters. Chem. Rev. 116, 7330–7396 (2016).
Di, X. Wang, Y. Wu, L. Zhang, Z. M. Dai, Q. Li, W. & Zhang, J. Enantioselective gold(I)-catalyzed heterocyclization–intermolecular exo [4 + 3]-cycloaddition reactions for the synthesis of chiral oxa-bridged benzocycloheptanes. Org. Lett. 21, 3018–3022 (2019).
Zhou, B. Li, L. Zhu, X. Q. Yan, J. Z. Guo, Y. L. & Ye, L. W. Yttrium-catalyzed intramolecular hydroalkoxylation/Claisen rearrangement sequence: efficient synthesis of medium-sized lactams. Angew. Chem. Int. Ed. 56, 4015–4019 (2017).
Zhang, Z. J. Zhang, L. Geng, R. L. Song, J. Chen, X. H. & Gong, L. Z. N-Heterocyclic carbene/copper cooperative catalysis for the asymmetric synthesis of spirooxindoles. Angew. Chem. Int. Ed. 58, 12190–12194 (2019).
Li, T.-R. Cheng, B.-Y. Fan, S.-Q. Wang, Y.-N. Lu, L.-Q. & Xiao, W.-J. Highly stereoselective [3 + 2] cycloadditions of chiral palladium-containing N ¹-1,3-dipoles: a divergent approach to enantioenriched spirooxindoles. Chem. Eur. J. 22, 6243–6247 (2016).

Acknowledgement

We are grateful to the National Science Foundation of China (No. 21822103, 21820102003, 91956201 and 21971056), the Program of Introducing Talents of Discipline to Universities of China (111 Program, B17019), the Natural Science Foundation of Hubei Province (2017AHB047) and the International Joint Research Center for Intelligent Biosensing Technology and Health for support of this research.

Competing interests

The authors declare no competing interests.

Additional information

Supplementary information The online version contains supplementary material available at https://doi.org/10.1038/s41557-021-xxxxx-x.

Correspondence and requests for materials should be addressed to Wen-Jing Xiao.

Peer review information Nature Synthesis thanks xxx xxx, xxx xxx and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Tables 1-3 are in the supplementary files section.

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