Practical and Convenient Synthesis of 1,6-Di- or 1,2,5,6-Tetra-arylhexa-1,3,5-trienes by the Dimerization of Pd(0)-Complexed Alkenylcarbenes Generated from π-Allylpalladium Intermediates

Stereoselective Synthesis of 1,3,5-Trienes from Alkynones and Allyl Carbonyl Compounds Through C-C σ-Bond Cleavage under Transition-Metal-Free Conditions

An atom-economical transition-metal-free protocol for the stereoselective synthesis of conjugated trienes has been developed. These transformations were realized through base promoted C-C σ-bond cleavage reactions of allyl carbonyl compounds. This...

Versatile Reactivity of Metalloid-Substituted π-Allylpalladium Species

π-Allylpalladium complexes can not only serve as electrophilic allylating agents for a broad range of nucleophiles, but also nucleophilic allylating agents for electrophiles depending on their electronic environments. In contrast to these typical reactivities of π-allylpalladium complexes, silylated and borylated π-allylpalladium species show unique reactivities that can allow versatile transformations in addition to simple allylation. Herein, four different types of transformations that are in principle achieved via the inherently reactive silylated and borylated π-allylpalladium species as common intermediates are described. An appropriate selection of ligands of the silylated and borylated π-allylpalladium species can allow control over the reaction pathways.

Step-wise and one-pot synthesis of highly substituted conjugated trienes from 2-oxobenzo[h]chromenes/2H-pyran-2-ones

A mild and efficient route for the synthesis of conjugated trienes via nitroethane-mediated ring contraction of 2-oxobenzo[h]chromenes/2H-pyran-2-ones followed by decarboxylative rearrangement of the obtained spirobutenolides and butenolides is described. The (E)-isomer of trienes was obtained by step-wise and one-pot approaches from 2-oxobenzo[h]chromenes. Butenolides 4a-l as new substrates have been developed for the construction of trienes. The mixture of the (E)- and (Z)-isomers of spirobutenolides undergoes decarboxylative rearrangement in the presence of sodium ethoxide as a base to yield the (E)-isomer of trienes, while the (E)-isomer of butenolides reacts to give a mixture of (2E,4E)- and (2E,4Z)-isomers of trienes in an almost steady ratio of 45 : 55 or 1 : 1.2. The structure and geometry of the obtained butenolides and trienes were confirmed by single-crystal X-ray analysis.

Construction and photoluminescence properties of a three-dimensional ZnII coordination network based on naphthalene-1,4-dicarboxylic acid and 1,6-bis(pyridin-3-yl)-1,3,5-hexatriene

In recent years, coordination polymers constructed from multidentate carboxylate and pyridyl ligands have attracted much attention because these ligands can adopt a rich variety of coordination modes and thus lead to the formation of crystalline products with intriguing structures and interesting properties. A new coordination polymer, namely poly[[μ₂-1,6-bis(pyridin-3-yl)-1,3,5-hexatriene-κ²N:N'](μ₃-naphthalene-1,4-dicarboxylato-κ⁴O¹,O^1':O⁴:O^4')zinc(II)], [Zn(C₁₂H₆O₄)(C₁₆H₁₄N₂)]_n, has been prepared by the self-assembly of Zn(NO₃)₂·6H₂O, naphthalene-1,4-dicarboxylic acid (1,4-H₂ndc) and 1,6-bis(pyridin-3-yl)-1,3,5-hexatriene (3,3'-bphte) under hydrothermal conditions. The title compound has been structurally characterized by IR spectroscopy, elemental analysis, powder X-ray diffraction and single-crystal X-ray diffraction analysis. Each Zn^II ion is six-coordinated by four O atoms from three 1,4-ndc^2- ligands and by two N atoms from two 3,3'-bphte ligands, forming a distorted octahedral ZnO₄N₂ coordination geometry. Pairs of Zn^II ions are linked by 1,4-ndc^2- ligands, leading to the formation of a two-dimensional square lattice (sql) layer extending in the ab plane. In the crystal, adjacent layers are further connected by 3,3'-bphte bridges, generating a three-dimensional architecture. From a topological viewpoint, if each dinuclear zinc unit is considered as a 6-connected node and the 1,4-ndc^2- and 3,3'-bphte ligands are regarded as linkers, the structure can be simplified as a unique three-dimensional 6-connected framework with the point symbol 4⁴6¹⁰8. The thermal stability and solid-state photoluminescence properties have also been investigated.

Direct introduction of a naphthalene-1,8-diamino boryl [B(dan)] group by a Pd-catalysed selective boryl transfer reaction

Under Palladium-catalysed Miyaura-type reaction conditions, a non-symmetrical diboron reagent, B(pin)-B(dan), was found to selectively deliver the B(dan) moiety to aryl bromides and chlorides. This method represents a direct and efficient way to masked boronic acids and boron-differentiated di- and polyboron compounds.