Phosphine-Catalyzed Internal Redox [4 + 2] Annulation between 1,4-Enynoates and Electron-Deficient Alkenes

DMAP-Catalyzed [4 + 2] Annulation of Hex-5-en-2-ynoates with Electron-Poor Alkenes

Herein, we report a DMAP-catalyzed [4 + 2] annulation reaction of hex-5-en-2-ynoates 1 with electron-poor alkenes 2, which affords exocyclic olefinic cyclohexenes 3 in good yields and excellent regio-, diastereo-, and E/Z selectivities. Distinguished from previous allenoate- or alkynoate-based substrates, hex-5-en-2-ynoates 1 use the β- and ε-carbons for the bond formation, presenting new and regiodivergent C4 synthons for Lewis base-catalyzed annulations.

Phosphine-Catalyzed Domino Annulation of γ-Vinyl Allenoates: Synthesis of Tetrahydrofuro[3,2-c]quinoline Derivatives

A novel phosphine-catalyzed domino annulation reaction of γ-vinyl allenoates and o-aminotrifluoacetophenones for the construction of terahydrofuro[3,2-c]quinoline derivatives has been developed. In this domino reaction, two kinds of terahydrofuro[3,2-c]quinoline compounds containing CF3 groups were obtained with good yields under mild conditions, three new C-N, C-C, and C-O bonds can be built in one step, and the reaction selectivity is achieved by adjusting the reaction conditions. Furthermore, preliminary studies on an asymmetric variant of this reaction proceeded with moderate enantioselectivity.

Expanding the Frontier of Linear Drug Design: Cu-Catalyzed Csp -Csp 3 -Coupling of Electron-Deficient SF4 -Alkynes with Alkyl Iodides

Despite the attractive properties of tetrafluorosulfanyl (SF4 ) compounds in drug discovery, medicinal research on SF4 molecules is hindered by the scarcity of suitable synthetic methodologies. Drawing inspiration from the well-established Sonogashira cross-coupling of terminal alkynes under Pd-catalysis, it is envisioned that SF4 -alkynes can serve as effective coupling partners. To overcome the challenges associated with the electron-deficient nature of SF4 -alkynes and the lability of the SF4 unit under transition-metal catalysis, an aryl radical mediated Csp -Csp 3 cross-coupling reaction is successfully developed under Cu catalysis. This methodology facilitates the coupling of SF4 -alkynes with alkyl iodides, leading to the immediate synthesis of SF4 -attached drug-like molecules. These findings highlight the potential impact of SF4 -containing molecules in the drug industry, paving the way for further research in this emerging field.

Access to 3-Aminomethylated Maleimides via a Phosphine-Catalyzed Aza-Morita-Baylis-Hillman Type Coupling

A designed method for the preparation of 3-aminomethylated maleimides via Morita-Baylis-Hillman (MBH) reaction was developed. This phosphine-catalyzed coupling adopted maleimides and 1,3,5-triazinanes as the substrate, giving a series of 3-aminomethylated maleimide derivatives with a double bond retained on the maleimide ring in 41-90% yield. Acylation, isomerization, and Michael addition of the obtained products demonstrated the synthetic application of the present protocol. The results of control experiments indicated that phosphorus ylide formation and elimination take place during the reaction pathway.

Synthesis of Phosphinic Amides from Chlorophosphines and Hydroxyl Amines via P(III) to P(V) Rearrangement

Phosphoranyl radicals are essential mediators to bring about new radicals but often produce a stoichiometric amount of phosphine oxide/sulfide waste. Herein, we devised a phosphorus-containing species as a radical precursor, but without the generation of phosphorus waste. Accordingly, a catalyst-free synthesis of phosphinic amides from hydroxyl amines and chlorophosphines via P(III) to P(V) rearrangement is described. Mechanistically, it may involve the initial formation of a R₂N-O-PR₂ species that undergoes homolysis of N-O bonds and subsequent radical recombination.

Phosphine-catalyzed activation of cyclopropenones: a versatile C3 synthon for (3+2) annulations with unsaturated electrophiles

We herein report a phosphine-catalyzed (3 + 2) annulation of cyclopropenones with a wide variety of electrophilic π systems, including aldehydes, ketoesters, imines, isocyanates, and carbodiimides, offering products of butenolides, butyrolactams, maleimides, and iminomaleimides, respectively, in high yields with broad substrate scope. An α-ketenyl phosphorous ylide is validated as the key intermediate, which undergoes preferential catalytic cyclization with aldehydes rather than stoichiometric Wittig olefinations. This phosphine-catalyzed activation of cyclopropenones thus supplies a versatile C3 synthon for formal cycloadditon reactions.