Stereoselective Synthesis of Tetraarylethylenes Enabled by Reductive anti‐1,2‐Dimetallation of Alkynes

Abstract

Tetraarylethylenes (TAEs) have been gaining attention from various scientific disciplines for their characteristic chemical and physical properties. From the synthetic perspective, however, efficient methods for the selective synthesis of different isomers of TAEs are still underdeveloped. Here, we report the regio-and stereoselective synthesis of TAEs by means of sodium-promoted reductive anti-1,2-dimagnesiation of alkynes. Subsequent transmetallation to zinc generates trans-1,2-dizincioalkenes, which underwent the stereoselective arylation under a palladium catalysis to afford a variety of TAEs that had been difficult to prepare according to the conventional procedures. In addition, the present method accommodates not only diarylacetylenes but also alkyl aryl acetylenes and thus enables to synthesize a wide range of allcarbon tetrasubstituted alkenes.

Reductive anti‐Dizincation of Arylacetylenes

“…Table 1 illustrates the optimization of reaction conditions for the model dizincation of tolane (1 a) followed by protonation to yield stilbene (2 a), focusing on zinc electrophiles. Following our previous dimagnesiation, [12] investigations began at 0 °C using simple zinc chloride. The reaction afforded 2 a in 38 % yield with high E selectivity, the remainder being mostly the recovery of 1 a (entry 1).…”

“…The conversions of vic-dimetalated alkenes back to the starting alkynes were also observed in the previous dimetalation reactions. [7,12] Scheme 2 illustrates the scope of the sequential dizincation/ cross-coupling. [17] With 1 a as the substrate, a variety of iodoarenes participated in the cross-coupling to afford 3 a-d in high yields.…”

“…[11] To avoid the unwanted ethyl transfer, we were compelled to use transmetalation between dimagnesiated species and zinc chloride (Figure 1D). [12] This dimagnesiation/transmetalation approach required the use of bis(trimethylsilyl)methylmagnesium chloride as an elaborate magnesium-based trapping agent, which is crucial for preventing undesired transmetalation of the alkyl group on the magnesium center and ensuring selective transfer of the vinylene unit to palladium.…”

Convenient construction of tetraphenylethene (TPE) derivatives through Cu(ii) mediated cascade dehydrogenation of EWG-activated diphenylmethane

“…To tackle the problem mentioned above and achieve the molecular complexity of TPEs, transition metal catalyzed methodologies such as Suzuki–Miyaura cross coupling are used to synthesize complicated TPE cores with good functional group tolerance (Scheme 1c). 9 In the past few years, with diarylalkyne, 10 vinylboronate, 11 and TPE-triazenes 12 as the starting materials, some new, advanced efforts, while capable of preparing complicated TPEs, to a certain extent, seem to be cumbersome and uneconomic for the preparation of simple symmetric electron-deficient TPEs considering the requirement of multi-step synthesis, complicated starting materials or complicated manipulation of the reaction process. Putting all this into perspective, developing a new and convenient methodology that is operationally simple, scalable, easy to handle, and able to circumvent the limitations of the existing well-established methods would be a desirable and synthetically complementary addition to the TPE toolkit.…”

Nucleophilic C4-selective (hetero) arylation of pyridines for facile synthesis of heterobiaryls

“…Pyridine, a prominent component in the realms of agrochemicals, pharmaceuticals, and functional materials (Vitaku et al, 2014;Zhong, et al, 2014), is often a key constituent of N-heterobiaryl scaffolds due to their rigid and adaptable three-dimensional structures (Wu and Chan, 2006;Ghoteimi et al, 2023;Yang et al, 2016;Lee, H. et al, 2019;Jo, W. et al, 2020;Li, H. et al, 2021;Shao et al, 2021;Nguyen, N. H. et al, 2022;Takahashi, F., and Yorimitsu, H., 2023). These structures are frequently used in the fabrication of therapeutic agents or as ligands for metal catalyst complexes.…”