We present the design and synthesis of polyoxazole-based macrocycles containing a phosphonate group. A reliable route was established that allows for convenient and versatile incorporation of various phosphonate functionalities such as phosphonate ester, acid, and salt at the macrocyclic ring periphery. Such unprecedented macrocyclic compounds are anticipated to be appealing candidates as telomerase inhibitors.

A one-pot cascade reaction for the synthesis of polysubstituted benzofurans and naphthopyrans from simple phenols and propargylic alcohols catalyzed by iron(III) is presented. The results demonstrate that the structural specificity for the formation of furan and pyran products is controlled by the structural nature of the propargylic alcohols. Namely, benzofurans could be synthesized efficiently from phenols and secondary propargylic alcohols in the presence of 5 mol% of iron(III) chloride hexahydrate (FeCl₃⋅6 H₂O) catalyst. On the other hand, pyran derivatives were obtained exclusively when tertiary propargylic alcohols were employed. Mechanistic studies revealed that presumably due to the discriminated steric effect of secondary and tertiary propargylic alcohols, the Fe-catalyzed Friedel–Crafts (F–C) reaction of phenols with the two types of alcohols proceeds via different models. Most importantly, we have demonstrated for the first time that fully 2,3,4-substituted naphthopyrans could be synthesized efficiently via the iron-catalyzed one-pot cascade reaction. Consequently, the results presented herein provide straightforward pathways for versatile syntheses of valuable benzofuran and pyran derivatives from simple phenolic compounds and propargylic alcohols.

A method for the efficient and reliable synthesis of aryl nitriles via the Cu₂O-catalyed cross-coupling of aryl boronic acids or esters and TMSCN is presented. A broad range of substrates decorated by electron-rich and deficient, sterically very congested, and labile functionalities were tolerated. Moreover, the reaction can proceed under mild conditions at room temperature. These advantages paired with the use of cheap, readily available, and halogen-free Cu₂O as catalysts make the protocol an appealing option for aryl cyanations.

The Suzuki–Miyaura cross-coupling of aryl sulfamates and boronic acids was investigated by using [1,3-bis(diphenylphosphanyl)propane]nickel(II) chloride {NiCl₂(dppp)} as the catalyst. The results showed that NiCl₂(dppp) is a highly active and general catalyst that allows effective Suzuki–Miyaura cross-coupling of aryl sulfamates with a slight excess amount of the boronic acid (1.2 equiv.) in the presence of a low catalyst loading (generally 1.0–1.5 mol-%). The method also displays broad generality not only to various aryl sulfamates, but also to an array of boronic acids. Furthermore, various functional groups are tolerated. These apparent advantages make NiCl₂(dppp) a practical and reliable catalyst system for the Suzuki–Miyaura coupling of aryl sulfamates.

We present a general approach to CP bond formation through the cross-coupling of aryl halides with a dialkyl phosphite, diphenylphosphine oxide, and diphenylphosphane by using [NiCl₂(dppp)] as catalyst (dppp=1,3-bis(diphenylphosphino)propane). This catalyst system displays a broad applicability that is capable of catalyzing the cross-coupling of aryl bromides, particularly a range of unreactive aryl chlorides, with various types of phosphorus substrates, such as a dialkyl phosphite, diphenylphosphine oxide, and diphenylphosphane. Consequently, the synthesis of valuable phosphonates, phosphine oxides, and phosphanes can be achieved with one catalyst system. Moreover, the reaction proceeds not only at a much lower temperature (100–120 °C) relative to the classic Arbuzov reaction (ca. 160–220 °C), but also without the need of external reductants and supporting ligands. In addition, owing to the relatively mild reaction conditions, a range of labile groups, such as ether, ester, ketone, and cyano groups, are tolerated. Finally, a brief mechanistic study revealed that by using [NiCl₂(dppp)] as a catalyst, the Ni^II center could be readily reduced in situ to Ni⁰ by the phosphorus substrates due to the influence of the dppp ligand, thereby facilitating the oxidative addition of aryl halides to a Ni⁰ center. This step is the key to bringing the reaction into the catalytic cycle.

We disclose that [1,3-bis(diphenylphosphino)methane]nickel(II) chloride [NiCl₂(dppp)] is a highly active, universally applicable, cheap, and stable catalyst for Suzuki–Miyaura cross-coupling reactions of aryl halides with a catalyst loading of lower than 1 mol%, and more notably, in the absence of extra supporting ligands. Under the optimized reaction conditions, a broad range of aryl bromides as well as the notoriously unreactive aryl chlorides, including activated, non-activated, deactivated, and heteroaromatic and sterically hindered substrates can be coupled smoothly with various boronic acids (47 examples, 48–98% yields). In addition, the transformation is tolerant of various functional groups such as ether, ester, ketone, aldehyde, cyano, and unprotected amino and hydroxy groups. Finally, the potential utilization of the methodology was further demonstrated by the gram-scale synthesis of several core structures of commercialized antihypertensive drugs and fungicides. Thus, the combination of high activity, broad applicability, cheapness, and high stability of NiCl₂(dppp) presented in this work constitutes one of the few prominent catalysts which allow for practical and reliable construction of biaryls and heterobiaryls with structural diversity from readily available aryl halides and boronic acids.

We present a highly active, inexpensive, universally applicable, and markedly stable [1,3-bis(diphenylphosphino)propane]nickel(II) chloride [Ni(dppp)Cl₂] catalyst that is capable of effecting the Suzuki–Miyaura cross-coupling of the inherently less reactive but readily available aryl tosylates and mesylates with only 1 mol% loading and in the absence of extra supporting ligand. Under the optimized reaction conditions, cross-coupling of a wide range of activated, non-activated, and deactivated, as well as sterically hindered and heteroaromatic substrates (36 examples) could proceed efficiently to afford the coupled products in 53–99% yields. Consequently, the results presented in this work provide a significant advance in Suzuki–Miyaura cross-coupling in terms of generality, practicality, and cost which are key concerns in recent research regarding transition metal-catalyzed cross-couplings.

A new method for the Suzuki–Miyaura cross-coupling of phenols and arylboronic acids through in situ phenol activation mediated by PyBroP is presented. The reaction proceeds efficiently by using cost-effective, markedly stable [NiCl₂(dppp)] (dppp=1,3-bis(diphenylphosphino)propane) as the catalyst in only 5 mol % loading, as well as in the absence of extra ligands. The method exhibits broad applicability and high efficiency towards a wide range of both phenols and boronic acids, including activated, nonactivated, deactivated, and heteroaromatic coupling partners. In addition, various functional groups, such as ether, amino, cyano, ester, and ketone groups, are compatible with this transformation. Notably, arylboronic acids containing an unprotected NH₂ group and 2-heterocyclic boronic acids, which are generally problematic for coupling under conventional conditions, are also viable substrates, although moderate yields were obtained for sterically hindered substrates. Consequently, the in situ cross-coupling methodology coupled with the use of an inexpensive and stable nickel catalyst provides a rapid and efficient pathway for the assembly of biaryls and heterobiaryls with structural diversity from readily available phenol compounds.