Cu^I/Rh^II-Catalyzed Tandem Convergent Multicomponent Reaction for the Regio- and Stereocontrolled Synthesis of γ-Oxo-β-amino Esters

Abstract

The first example of a highly regio- and stereoselective catalytic method for the three-component one-pot synthesis of highly functionalized α-vinylated γ-oxo-β-amino esters is disclosed. In this catalytic triad, the Cu(I)-catalyst selectively catalyzes the cycloaddition of the 1-alkyne and sulfonyl azide first resulting in the corresponding 1-sulfonyl-1,2,3-triazole. An α-imino Rh(II)-carbene is generated from an open-chain α-imino diazo of the triazole, and this species reacts with γ-hydroxy α,β-unsaturated esters to form allylic (Z)-amino vinyl ethers. Rapid deconjugative [3,3]-sigmatropic rearrangement affords the α-vinyl γ-oxo-β-amino esters in high yields with high levels of diastereoselectivity.

Tandem O–H Insertion/[3,3]‐Sigmatropic Rearrangement of Rhodium Carbenoids with 2‐Furfuryl Alcohols: A Strategy To Access Polysubstituted Furans

“…On the basis of the experimental results and previous reports, we propose a plausible mechanism in Scheme . Initially, N ‐sulfonyl‐1,2,3‐triazole 2a is converted into α‐diazo imine intermediate A by ring‐chain tautomerization; this intermediate subsequently reacts with the rhodium catalyst to afford α‐imino rhodium carbenoid intermediate B with the loss of molecular nitrogen.…”

“…Moreover, Fokin and co‐workers demonstrated a similar type of transformation with propargyl alcohols . Subsequently, Lee and co‐workers reported the regio‐ and stereocontrolled synthesis of γ‐oxo‐β‐amino esters starting from N ‐sulfonyl‐1,2,3‐triazoles and γ‐hydroxy‐α,β‐unsaturated esters . Furthermore, N ‐sulfonyl‐1,2,3‐triazoles have also been extended to Morita–Baylis–Hillman (MBH) adducts for the preparation of α‐methylene‐δ‐oxo‐γ‐amino esters .…”

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.…”

“…To study the intrinsic aspects of the bimetallic catalyst system, we first conducted the reaction between the 1,2,3‐triazole 1 a and allyl alcohol ester 2 a in the presence of the Rh 2 (esp) 2 catalyst and 4 Å M.S . (Table , entry 1).…”

Synthesis of 2‐Substituted 2‐Amino Ketones by Rhodium‐Catalyzed Reaction of N‐Sulfonyl‐1,2,3‐triazoles with 2‐Alkenols

“…The utility of this method is demonstrated by an application to a formal synthesis of (–)‐ α ‐conhydrine. A study on the use of 2,3‐alkadienols is also reported [13]…”