Synthesis of α-methylene-δ-oxo-γ-amino esters via Rh(ii)-catalyzed coupling of 1-sulfonyl-1,2,3-triazoles with Morita–Baylis–Hillman adducts

Abstract

A rhodium(ii)-catalyzed coupling of 1-sulfonyl-1,2,3-triazoles, prepared from 1-alkynes and sulfonyl azides, with Morita-Baylis-Hillman (MBH) adducts afforded highly functionalized α-methylene-δ-oxo-γ-amino esters in excellent yields with broad functional group tolerance. This transformation can also be successfully accomplished as a multicomponent all-in-one-pot reaction of 1-alkynes, sulfonyl azides and MBH adducts in the presence of Cu(i) and Rh(ii) catalysts.

Bimetallic Rhodium(II)/Indium(III) Relay Catalysis for Tandem Insertion/Asymmetric Claisen Rearrangement

“…Among them, 1,2,3‐triazoles, firstly explored as synthetic equivalents of azavinyl carbenes by Gevorgyan, Fokin, and co‐workers, have the capacity of the formation of unique rhodium(II)‐bound imino carbene intermediates I with the loss of dinitrogen, enabling numerous useful synthetic transformations . For example, the tandem insertion/[3,3]‐ sigmatropic rearrangement of N ‐sulfonyl‐1,2,3‐triazoles with allyl alcohol derivatives, give access to β‐amino and γ‐amino acid derivatives, which are highly valuable in many scientific areas . Nevertheless, the catalytic enantioselective version of this tandem process remains elusive.…”

“…In consequence, chiral rhodium(II) catalyst was less efficient in this transformation. Benefiting from the well‐organized six‐membered ring transition state of the final [3,3]‐sigmatropic rearrangement step, chiral allyl alcohols could be employed to achieve enantioenriched rearrangement products –. However, regarding to achiral allyl alcohol‐derivatives, this is beyond reach of the aforementioned strategy.…”

Rhodium(II)‐Catalyzed Reaction of 1‐Tosyl‐1,2,3‐triazoles with Morita–Baylis–Hillman Adducts: Synthesis of 3,4‐Fused Pyrroles

“…Solvent effect was then tested with DBU as the base (entry [8][9][10][11]. The results show that the nonpolar solventt oluene is the best choice.M oreover, the yield did not increase either at ah igher reaction temperature or a lower reaction temperature (entry [12][13][14].W e envisioned that the additional oxidants would promote the reaction. Therefore, oxidantsl ike DDQ or PIDA werea dded, but the desired product could not be obtained (entry [15][16].…”

“…[12] Soon afterwards, an ovel protocol for the synthesiso fu nsymmetrical indigo-like (E)-a-aminoe naminones by rhodiumc atalyzed OÀH insertiona nd subsequentr earrangement of isatins with 1tosyl-1,2,3-triazoles has also been reported by us. [13] Up to now, the direct O-H insertions of a-imino rhodium carbenoids with propers ubstrates, [14] taking benzylic alcohol [14e] for example, have been well studied.M oreover,s ome methods have been developed for the construction of nitrogen-containing heterocycles (such as pyrrole skeleton) based on OÀHi nsertion and subsequentr earrangement. [14a] With our continuing studies on the Rh II -catalyzedt ransformation of triazoles, we supposed this rhodium-catalyzed OÀHi nsertion/rearrangement strategy can be further appliedt oa fford more attractive nitrogen-containing heterocycles such as 3,4-fusedp yrroles by using Morita-Baylis-Hillman adductsa ss tartingm aterials.…”

“…Moreover, the use of 1,2-dichloroethane (DCE) or toluene as the solventd id not increase the yield of 3aa (entry [8][9]. The addition of Lewis acidh ave no positivee ffects (entry [10][11][12][13][14]. Finally, the reaction of MBH adduct 1a with 1.2 equiv of triazole 2a catalyzed by Rh 2 (Oct) 4 in CHCl 3 at 75 8Cw ere set as the optimum reaction conditions.…”