Palladium-Catalyzed Three-Component Selective Aminoallylation of Diazo Compounds

Abstract

We describe a Xantphos-containing dinuclear palladium complex-enabled geminal aminoallylation of diazocarbonyl compounds, which selectively provides a range of quaternary α-amino esters. Direct N–H insertion, allylic alkylation of amino nucleophiles, and diene formation were not observed under standard conditions. Mechanistic studies indicated that a relayed pathway via allylation of the N–H insertion product or [2,3]-sigmatropic rearrangement of an ylide intermediate was unlikely.

Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C−H Functionalization and Allylic Alkylation

“…[71][72][73][74] In this context, the catalytic construction of diaryl quaternary center with an allylic synthetic handle from the carbene Chemistry-A European Journal www.chemeurj.org induced CÀ H functionalization of a simple arene is highly desirable, but remains underexplored probably due to the difficulties in the combination of metal-carbene insertion process with allylic alkylation (Scheme 1a,ii). [75][76][77][78] As a continuation of our efforts in development of dirhodium(II)/Xantphos-catalyzed three-component difunction-alization of diazo compounds, [79,80] we envisioned the electrophilic allyl reagents might be ready to intercept the α, αdiarylacetate intermediate that is generated from α-diazo esters and N, N-disubstituted anilines by a dirhodium complex (Scheme 1b). Herein, we wish to report a three-component reaction of N, N-disubstituted aniline, α-diazo ester, and an allylic electrophile using a dirhodium(II)/Xantphos catalyst, furnishing various aniline derivatives with diaryl allylic quaternary centers in good yields (Scheme 1b).…”

“…In addition, the introduction of an allylic unit into quaternary center is an important research topic in organic synthesis, since the high versatility of the allylic unit for further transformations will provide a ready entry to various quaternary frameworks [71–74] . In this context, the catalytic construction of diaryl quaternary center with an allylic synthetic handle from the carbene induced C−H functionalization of a simple arene is highly desirable, but remains underexplored probably due to the difficulties in the combination of metal‐carbene insertion process with allylic alkylation (Scheme 1a,ii) [75–78] …”

Forming All-Carbon Quaternary Centers by Geminal Difunctionalization of Diazo Compounds with N,N-Disubstituted Anilines and Allylic Carbonates

“…By using allylic carbonates as the reagents, Wang, Hu, and Huang have realized the three-component reactions of anilines/alcohols, diazo compounds, and allylic carbonates, which proceeds through a sequential N–H/O–H insertion and a substitution reaction (Scheme a). Just recently, Wang reported a rhodium/XantPhos-catalyzed difunctionalization of diazoacetates through a tandem Csp 2 –H insertion of phenols and allylic alkylation (Scheme b) .…”

Tunable Key [3 + 2] and [2 + 1] Cycloaddition of Enaminones and α-Diazo Compounds for the Synthesis of Isomeric Isoxazoles: Metal-Controlled Selectivity

“…On the other hand, owing to their high and versatile reactivity, the stable α-diazo compounds, such as α-diazo ketones and α-diazo esters, have been proven to be indispensable building blocks in modern organic synthesis . One of the representative transformations of such diazo compounds is the formation of metal carbene species with a variety of transition metals, such as copper, palladium, iridium, silver, iron, rhodium, etc. Meanwhile, enaminones have in recent years found rapidly growing application in the designation of diverse organic reactions .…”