Organic chemistry frontiers : an international journal of organic chemistry最新文献

Organic semiconductors that exhibit strong absorption in the near-infrared (NIR) region have received increasing attention as new organic optoelectronic materials. In this paper, we report the synthesis, absorption and semiconducting properties of a new quinoid molecule based on bis(thiophene-diketopyrrolopyrrole) (2DPP-Q-CN) with a long conjugation length. The results reveal that this new quinoid molecule shows strong absorption in the NIR region with a molar extinction coefficient of 380 000 M⁻¹ cm⁻¹. Moreover, the thin film of 2DPP-Q-CN exhibits balanced ambipolar semiconducting properties with hole and electron mobilities up to 0.19 and 0.20 cm² V⁻¹ s⁻¹, respectively.

An efficient synthesis of ferrocene derivatives via Ru(ii)-catalyzed direct selective C–H mono-alkynylation with easily accessible bromoalkyne compounds under the influence of weakly coordinating amide groups has been presented. This protocol provides an approach for accessing various ferrocene derivatives with easily transformed alkynes using carboxamides, giving alkynylated ferrocenes in up to 89% yield.

Presented herein is a substrate-controlled diversity-oriented approach to access skeletally different frameworks from ortho-vinyl-functionalised 1,3-enynes and imines via palladium catalysis. A variety of benzofulvenes were constructed in moderate to high yields, enantioselectivity and E-selectivity, through a cascade vinylogous addition, 5-exo-trig migratory insertion and β-H elimination process. In addition, modifing the vinyl substitutions of 1,3-enyne substrates could switch the Oppolzer cyclisation into a 6-endo-trig pattern, which finally furnished formal 1-naphthylated amines enantioselectively under similar conditions. Moreover, the 2-furyl imine-derived naphthalene products further underwent a domino intramolecular Diels–Alder cycloaddition reaction, furnishing complex oxabicyclo[2.2.1]heptane architectures. The efficient construction of distinctly structured libraries exhibited well the versatility of the current substrate-controlled strategy.

A variety of enantioenriched spirofuro[2,3-b]azepine-5,3′-indoline derivatives (dr > 20 : 1, up to 96% ee) were facilely synthesized through cycloisomerization/asymmetric formal [4 + 3] cycloaddition reactions of enyne-amides with isatin-derived enals under gold(i)/chiral N-heterocyclic carbene (NHC) relay catalysis. The method is practical and useful because of the convenient one-step procedure, high stereoselectivity, and good functional-group tolerance.

The Matteson homologation is found to be a versatile tool for the stereoselective synthesis of polyunsaturated alkyl boronic esters, which are excellent precursors for the construction of five- and six-membered carbocycles via ring-closing metathesis. The high diversity of the Matteson reaction allows for the preparation of highly substituted cyclic boronic esters, which are also suitable for further homologations.

Substituted malonic esters are valuable substrates for desymmetrization to tertiary and quaternary stereocenters, as they can be easily accessed via substitution and the resulting chiral monoesters are versatile building blocks and prevalent motifs in bioactive molecules. Here, building upon a previously reported dinuclear zinc-catalyzed asymmetric hydrosilylation that generated quaternary stereocenters, a pipecolinol-derived tetradentate ligand was devised to extend the desymmetric protocol to monosubstituted malonic esters. This new variation of the desymmetrization has allowed the preparation of structurally diverse tertiary stereocenters in good yields and enantioselectivity. The synthetic utility of these enantioenriched products has also been illustrated in a mild amination procedure to synthesize chiral amino alcohols.

The functional group migration strategy could facilitate the construction of complex structures from relatively simple starting materials. In contrast to the well-developed transition-metal catalyzed intramolecular 1,3-hydride migration, 1,3-carbon migration in allylic alcohols is marginally less reported. Herein, we report a protocol for Ru-catalyzed 1,3-indolyl migration under mild conditions. In this study, we disclosed that indoles have better migration ability than phenyl groups. Overall, this catalytic system enabled the simultaneous selective C(sp³)–C(sp²) bond cleavage and reconstruction, which allow for an immediate synthesis of β-indolyl ketones with a broad substrate scope and reasonable yields.

N-Hydroxy benzimidazoles (NHBIs) have proved to be efficient hydrogen atom abstractors (HAAs), but their further application in catalysis has been rarely explored since the first report. Herein, we describe their catalytic performance in other hydrogen atom transfer reactions. Specifically, we realized a copper/NHBI co-catalyzed synthesis of 2-phosphonopyrroles via cascade [3 + 2] annulation–aromatization. And NHBI was demonstrated to play a crucial role in both the annulation step and the subsequent aromatization. Besides, NHBI-catalyzed annulation with an imine and C–H oxidation were also feasible. Notably, NHBIs bearing a docking group that can recognize substrates were also investigated as bifunctional HAT catalysts for the first time.

An enantioselective Ni-catalyzed syn-hydrocyclization of alkyne-tethered ketoamides for the synthesis of α-hydroxy γ-lactams is reported. Using Ni(OTs)₂·6H₂O/(S,S)-Me-Duphos as a precatalyst and (EtO)₂MeSiH as a hydride source, a broad range of enantioenriched γ-lactams with a fully substituted stereogenic center are obtained in 32–84% yields with 87.5 : 12.5–97 : 3 er. Synthetic utilities, including scale-up reaction and product derivatization, are also demonstrated. This research presents a regioselective functionalization of alkynes and provides an efficient strategy to access functional group-enriched chiral heterocycles.