Efficient Synthesis of 2-Methylene-3phosphorylalkanoates: Phosphorylation of Baylis–Hillman Bromides via an S N 2-S N 2′ Strategy

A novel synthesis of 2-methylene-3-phosphorylalkanoates under mild conditions is described. Thus, Balyis–Hillman bromides react with secondary phosphine oxides or H-phosphonites in the presence of DABCO via an S _N 2-S _N 2′ protocol to produce the target compounds in good yields.     

Montmorillonite K10/ZnCl2 Catalyzed Alkyl Disulfide Substitution Reactions: Preparation of Thiomethyl Derivatives for the Synthesis of Organic Conducting Materials

Experiments are described detailing a method for the direct introduction of thiomethyl groups into activated benzenes, thiophene and benzo[b]thiophene using an activated mesoporous clay to promote thiomethyl substitution. Elaboration of 2,3-dithiomethylbenzo[b]thiophene, a product of the clay-catalyzed reaction of benzo[b]thiophene with dimethyl disulfide, to a tetrathiafulvalene derivative is described.     

Ring Opening of Donor–Acceptor Cyclopropanes with the Azide Ion: A Tool for Construction of N‐Heterocycles

A general method for ring opening of various donor–acceptor cyclopropanes with the azide ion through an S_N2‐like reaction has been developed. This highly regioselective and stereospecific process proceeds through nucleophilic attack on the more‐substituted C2 atom of a cyclopropane with complete inversion of configuration at this center. Results of DFT calculations support the S_N2 mechanism and demonstrate good qualitative correlation between the relative experimental reactivity of cyclopropanes and the calculated energy barriers. The reaction provides a straightforward approach to a variety of polyfunctional azides in up to 91 % yield. The high synthetic utility of these azides and the possibilities of their involvement in diversity‐oriented synthesis were demonstrated by the developed multipath strategy of their transformations into five‐, six‐, and seven‐membered N‐heterocycles, as well as complex annulated compounds, including natural products and medicines such as (?)‐nicotine and atorvastatin.     

An emerging post‐polymerization modification technique: The promise of thiol‐para‐fluoro click reaction

Post‐polymerization modification (PPM) of polymers is extremely beneficial in terms of designing brand new synthetic pathways toward functional complex polymers. Fortunately, the new developments in the field of organic chemistry along with controlled/living radical polymerization (CLRP) techniques have enabled scientists to readily design and synthesize the functionalized‐polymers for wide range of applications via the PPM. In this regard, the reactivity of para‐fluorine atom in the fluorinated aromatic structures toward the nucleophilic substitution reactions has made the polymers possessing this group to become a very strong candidate that can undergo efficient PPM. Besides, it has been proven that the thiol‐functionalized compounds react with the para‐fluorine atom of the pentafluorophenyl group more rapidly and efficiently than the amine‐ and the hydroxyl‐functionalized compounds. Furthermore, the milder experimental conditions to achieve quantitative conversions have led to the reaction between the thiol and the structures possessing pentafluorophenyl groups to be referred to as a click‐type reaction. Given this information, this review article aims to present the scientific developments regarding the thiol‐para‐fluoro “click” (TPF‐click) chemistry, and its impact on PPM to construct novel polymeric structures. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1181–1198     

Stabilizing RbPbBr3 Perovskite Nanocrystals through Cs+ Substitution

ABX₃-type halide perovskite nanocrystals (NCs) have been a hot topic recently due to their fascinating optoelectronic properties. It has been demonstrated that A-site ions have an impact on their photophysical and chemical properties, such as the optical band gap and chemical stability. The pursuit of halide perovskite materials with diverse A-site species would deepen the understanding of the structure–property relationship of the perovskite family. In this work we have attempted to synthesize rubidium-based perovskite NCs. We have discovered that the partial substitution of Rb⁺ by Cs⁺ help to stabilize the orthorhombic RbPbBr₃ NCs at low temperature, which otherwise can only be obtained at high temperature. The inclusion of Cs⁺ into the RbPbBr₃ lattice results in highly photoluminescent Rb_1−xCs_xPbBr₃ NCs. With increasing amounts of Cs⁺, the band gaps of the Rb_1−xCs_xPbBr₃ NCs decrease, leading to a redshift of the photoluminescence peak. Also, the Rb_1−xCs_xPbBr₃ NCs (x=0.4) show good stability under ambient conditions. This work demonstrates the high structural flexibility and tunability of halide perovskite materials through an A-site cation substitution strategy and sheds light on the optimization of perovskite materials for application in high-performance optoelectronic devices.     

Phosphazene Base tBu-P4 Catalyzed Methoxy–Alkoxy Exchange Reaction on (Hetero)Arenes

The organic superbase tBu-P4 catalyzes methoxy-alkoxy exchange reactions on (hetero)arenes with alcohols. The catalytic reaction proceeded efficiently with electron-deficient methoxy(hetero)arenes as well as with a variety of alcohols, including 3-amino-1-propanol, β-citronellol, menthol, and cholesterol. An intramolecular version of this reaction furnished six- and seven-membered ring compounds.