The development of transition-metal-catalyzed methods
for the synthesis
of P-chiral phosphine derivatives poses a considerable challenge.
Herein, we present a direct Pd/Xiao-Phos-catalyzed cross-coupling
reaction of easily accessible secondary phosphine oxides and aryl
bromides, which provides rapid access to P-chiral phosphine oxides.
The reaction proceeds efficiently with a wide array of reaction partners
to deliver various tertiary phosphine oxides in up to 96% yield and
97% ee. Moreover, the synthesis of DiPAMP ligand and its analogues
was also realized, which demonstrates a suitable pathway to switching
the branched chain of DiPAMP.
Over the past years, the metal‐catalyzed dearomative cycloaddition of 3‐nitroindoles and 2‐nitrobenzofurans have emerged as a powerful protocol to construct chiral fused heterocyclic rings. However, organocatalytic dearomative reaction of these two classes of heteroarenes has become a long‐standing challenging task. Herein, we report the first example of phosphine‐catalyzed asymmetric dearomative [3+2]‐cycloadditio of 3‐nitroindoles and 2‐nitrobenzofurans, which provide a new, facile, and efficient protocol for the synthesis of chiral 2,3‐fused cyclopentannulated indolines and dihydrobenzofurans by reacting with allenoates and MBH carbonates, respectively through a dearomative [3+2]‐cycloaddition.
A novel chiral biamide-phosphine multifunctional catalyst has been developed that mediates the asymmetric intermolecular Michael addition of β-carbonyl esters to β-trifluoromethyl enones and 3-aroyl acrylates in the presence of competing methyl acrylate and the inorganic base. This method provides a facile access to structurally diverse trifluoromethyl and quaternary stereogenic centers with excellent enantioselectivity (up to 99% ee) and good diastereoselectivity (up to 13:1 dr). The addition of the inorganic base (KPO) does not cause the background racemic reaction and enhances the reactivity by serving as a co-catalyst.
A palladium-catalyzed intermolecular dynamic kinetic asymmetric dearomatization of 3-arylindoles with internal alkynes was developed with the use of achiral Xantphos and chiral sulfinamide phosphine ligand (PC-Phos) as the co-ligands. This method could deliver various spiro[indene-1,3'-indole] compounds in good yields (up to 95 % yield) with up to 98 % ee. The salient features of the transformation include the use of readily available substrates, ease of scale-up and the versatile functionalization of the products. The mechanistic experiments gave some insights on active intermediates.
A novel phosphine-catalyzed, highly enantioselective umpolung addition of trifluoromethyl ketimines to Morita-Baylis-Hillman carbonates was developed and it provides facile access to optically active trifluoromethyl amines with a chiral tertiary stereocenter under mild reaction conditions. The salient features of this reaction include general substrate scope, mild reaction conditions, good yields, high enantioselectivity, ease of scale-up to gram scale, and further transformations of the products.
Herein, we report a gold-catalyzed highly site-selective C(sp)-H functionalization of unactivated arenes with α-aryl-α-diazoesters with electron-withdrawing substituents as induced groups on aryl rings. Furthermore, the induced groups are useful for further synthetic transformations.
Addition of P–H
species to carbonyl groups, namely the Pudovik
reaction, normally delivers hydroxyl phosphorus compounds, along with
phosphate byproducts in some cases. A few controllable systems starting
from phosphites were set up to mainly provide the phosphates. Herein,
we present a highly selective protocol starting from phosphonate precursors
leading to phosphinate derivatives. Enantioenriched phosphinates were
successfully achieved from chiral phosphine oxide precursors. Experimental
and theoretical investigations were conducted to understand the mechanistic
details.
A highly enantioselective palladium/WJ-Phos-catalyzed Suzuki−Miyaura coupling reaction for efficient construction of axially chiral biaryl monophosphine oxides was developed. A series of axially chiral biaryl monophosphine oxides were obtained in good yields and with high enantioselectivities. The practicability of this reaction was validated in the straightforward synthesis of axially chiral biaryl monophosphine ligand and demonstrated by a 100-g-scale synthesis. Moreover, various functionalizations of the product make it as a platform molecule for synthesis of other chiral biaryl phosphines.
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