2021
DOI: 10.1021/jacs.1c05701
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Dirhodium(II)/Xantphos-Catalyzed Relay Carbene Insertion and Allylic Alkylation Process: Reaction Development and Mechanistic Insights

Abstract: Although dirhodium-catalyzed multicomponent reactions of diazo compounds, nucleophiles and electrophiles have achieved great advance in organic synthesis, the introduction of allylic moiety as the third component via allylic metal intermediate remains a formidable challenge in this area. Herein, an attractive three-component reaction of readily accessible amines, diazo compounds, and allylic compounds enabled by a novel dirhodium­(II)/Xantphos catalysis is disclosed, affording various architecturally complex a… Show more

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Cited by 50 publications
(41 citation statements)
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“…This result, together with the reactions in Scheme d, imply that C–H functionalization proceeds prior to O-allylation in the reaction steps for the formation of 5aa . On the basis of previous reports and these experimental results, we propose that the reaction is most likely to proceed through a tandem process of Rh­(II) carbenoid induced C–H functionalization and [Rh 2 ]/Xantphos-catalyzed allylic alkylation, which is distinctive from the well-known [Rh­(II) 2 ]-catalyzed MCRs, wherein an active ylide/zwitterionic intermediate generated in situ was directly trapped by an electrophile. , The necessity of the Xantphos ligand in this catalysis may be owing to the coordination modification of the active center of dirhodium, leading to a novel catalytic activity for allylic alkylation. Nonetheless, the possibility of the formation of monorhodium species cannot be completely ruled out at the present stage. To gain some further insights into the allylic substitution process, compound 5aa was treated with deuterated allyl methyl carbonate under standard conditions, and two products, 6a-D and 6a-D′ , were obtained in 50:50 ratio (Scheme f).…”
Section: Resultsmentioning
confidence: 61%
See 1 more Smart Citation
“…This result, together with the reactions in Scheme d, imply that C–H functionalization proceeds prior to O-allylation in the reaction steps for the formation of 5aa . On the basis of previous reports and these experimental results, we propose that the reaction is most likely to proceed through a tandem process of Rh­(II) carbenoid induced C–H functionalization and [Rh 2 ]/Xantphos-catalyzed allylic alkylation, which is distinctive from the well-known [Rh­(II) 2 ]-catalyzed MCRs, wherein an active ylide/zwitterionic intermediate generated in situ was directly trapped by an electrophile. , The necessity of the Xantphos ligand in this catalysis may be owing to the coordination modification of the active center of dirhodium, leading to a novel catalytic activity for allylic alkylation. Nonetheless, the possibility of the formation of monorhodium species cannot be completely ruled out at the present stage. To gain some further insights into the allylic substitution process, compound 5aa was treated with deuterated allyl methyl carbonate under standard conditions, and two products, 6a-D and 6a-D′ , were obtained in 50:50 ratio (Scheme f).…”
Section: Resultsmentioning
confidence: 61%
“…As a continuation of our interest in multicomponent reactions under a unique dirhodium­(II)/diphosphine catalysis, we envisioned a novel multicomponent reaction of unprotected phenols, diazo compounds, and allylic compounds, which may proceed via a sequence of para -selective C­(sp 2 )–H functionalization followed by an allylic alkylation (Scheme c). While such a strategy can provide a straightforward route to phenol derivatives bearing diaryl-substituted all-carbon quaternary centers, some uncertainties might severely impede the implementation of this strategy; e.g., (1) the catalytic reactivity of the dirhodium­(II)/ligand for the proposed individual steps of the tandem process is unclear; (2) C­(sp 2 )–H functionalization reaction of free phenols with a Rh­(II) carbenoid still remains an unknown challenge; (3) the conceivable competitive reactions of O–H insertion, cyclopropanation of a metal carbene and CC bond, and direct C/O-allylation of phenol with allylic compounds , can cause considerable difficulties in chemoselectivity or site-selectivity control.…”
Section: Introductionmentioning
confidence: 99%
“…Moreover, thiophenols with electron-withdrawing groups (CF 3 , CO 2 Me) or electron-donating groups (Me, t Bu, and OMe) were able to afford the corresponding products in satisfactory yields (8)(9)(10)(11)18). This reaction could proceed effectively with thiophenols containing meta-group and sterically impeding orthohalogen/methyl/ ester functionality, which delivered a variety of target molecules in moderate yields (12)(13)(14)(15)(16)(17)(18). Naphthalene-2-thiol was also compatible with this transformation (19).…”
Section: Scope Of Substratesmentioning
confidence: 97%
“…In this regard, chemists have been devoting continuous efforts to pursuing the versatile transformations of diazo compounds for the synthesis of a variety of high-value molecules, such as pharmaceuticals and natural products [4][5][6][7][8] . Among them, the difunctionalization of diazo compounds has emerged as an important tool for the formation of challenging carbon-carbon and carbon-heteroatom bonds with the introduction of multiple functional groups [9][10][11][12][13][14][15][16][17] . Over the last decades, transition-metal (such as Rh, Cu, Fe, Pd, etc) catalyzed difunctionalization of diazo compounds with nucleophiles and electrophiles has undergone a flourishing development because of the unique reaction properties of metal carbene (Fig.…”
mentioning
confidence: 99%
“…Experimentally, studying axial coordination by tethering them to bridging ligands has emerged as a viable strategy to circumvent the weak interaction associated with axial ligands. This provides a bias for the site of reactivity and ensures a high local concentration for axial coordination. We have investigated the role of axial coordination by designing bridging ligands that have pendant thioether moieties that are capable of axial coordination (complexes 1 – 6 , Figure ).…”
mentioning
confidence: 99%