Perchlorate‐Free Pyrotechnic Formulations Utilizing Energetic Chlorine Donors: 1‐CDN, 11‐CDN, 13‐CDN

Several novel materials were investigated as energetic chlorine donors, specifically for the preparation of perchlorate‐free pyrotechnic formulations with low‐smoke output. The novel compounds, 2‐chloromethyl‐2‐methyl‐5,5‐dinitro‐1,3‐dioxane (1‐CDN), 2,2‐bis(chloromethyl)‐5,5‐dinitro‐1,3‐dioxane (13‐CDN), and 2‐(dichloromethyl)‐2‐methyl‐5,5‐dinitro‐1,3‐dioxane (11‐CDN), were formulated with a variety of fuels and oxidizers and their resulting colored flames analyzed for color quality. The preparation and preliminary characterization of these energetic chlorine donors are described.     

New Substituted 1‐Aryl‐4,4,6‐Trimethyl‐3,4‐Dihydropyrimidine‐2‐(1H)Thiones; A Metal‐Free and Solvent‐Free Synthesis,Characterization, and Lymphoid Tyrosine Phosphatase Inhibition Studies

A series of fourteen 3,4‐dihydropyrimidine‐2‐thiones ( 3a–n ) were synthesized by a green protocol, and their structures were characterized by spectroanalytical data. The compounds were obtained in high yields by efficient annulation of mesityl oxide (4‐methylpent‐3‐en‐2‐one) with anilines in the presence of potassium thiocyanate. The reaction is essentially metal‐catalyst‐ and solvent‐free, as mesityl oxide itself is the solvent as well as the reactant. The compounds were tested for their ability to inhibit the lymphoid tyrosine phosphatase PTPN22, and 5 of the 14 compounds exhibited IC₅₀ values in the mid‐micromolar range, with the most potent hit being the compound 3d , having a methoxy substituent at the 2‐position of the phenyl ring with an IC₅₀ = 18 ± 1 μM, and second most potent compound ( 3c ) with an IC₅₀ value of 45 ± 3 μM, having methyl substituents at both 2‐ and 4‐position of the phenyl ring.     

Stereoselective Solvent‐Free Synthesis of 4‐Hydroxy‐1,3‐thiazinane‐2‐thiones

An efficient solvent‐free one‐pot stereoselective synthesis of 4‐hydroxy‐1,3‐thiazinane‐2‐thione derivatives from the reaction of primary amines and carbon disulfide in the presence of α,β‐unsaturated aldehydes has been reported. The 4‐hydroxy‐1,3‐thiazinane‐2‐thione derivatives were easily converted to the related dehydrated or acetylated products.     

Transition‐Metal‐Free Synthesis of 1,3‐Butadiene‐Containing π‐Conjugated Polymers

This work describes the synthesis of π‐conjugated polymers possessing arylene and 1,3‐butadiene alternating units in the main chain by the reaction of α,β‐unsaturated ester/nitrile containing γ‐H with aromatic/heteroaromatic aldehyde compound. By using 4‐(4‐formylphenyl)‐2‐butylene acid ethyl ester as a model monomer, the different polymerization conditions, including catalyst, catalyst amount, and solvent, are optimized. The polymerization of 4‐(4‐formylphenyl)‐2‐butylene acid ethyl ester is carried out by refluxing in ethanol for 72 h with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as a catalyst to give a 1,3‐butadiene‐containing π‐conjugated polymer, poly(phenylene‐1,3‐butadiene), in 84.3% yield with and / (PDI) estimated as 6172 and 1.65, respectively. Based on this new methodology, a series of π‐conjugated polymers containing 1,3‐butadiene units with different substituents are obtained in high yields. A possible mechanism is proposed for the polymerization through a six‐membered ring transition state and then a 1,5‐H shift intermediate.

     

Solvent‐Free Synthesis of Diphenyl [2‐(Aminocarbonyl)‐1,2‐dihydroisoquinolin‐1‐yl]phosphonates from Isoquinoline,Isocyanates, and Diphenyl Phosphonate

The 1 : 1 intermediates generated by addition of isoquinoline to isocyanates were trapped by diphenyl phosphonate to yield diphenyl [2‐(aminocarbonyl)‐1,2‐dihydroisoquinolin‐1‐yl]phosphonates in good yields under solvent‐free conditions.     

Protecting‐Group‐Free Enantioselective Synthesis of (−)‐Pallavicinin and (+)‐Neopallavicinin

The first enantioselective synthesis of (?)‐pallavicinin and (+)‐neopallavicinin has been achieved in 15 steps. The described synthesis avoids protecting‐group manipulations by synthesis designs predicated on highly chemo‐ and stereoselective transformations. Highlights of the synthesis include a palladium‐catalyzed enantioselective decarboxylative allylation to form the chiral all‐carbon quaternary stereocenter, a palladium‐catalyzed oxidative cyclization to assemble the [3.2.1]‐bicyclic moiety, and an unprecedented LiBHEt₃‐induced fragmentation/protonation of an α‐hydroxy epoxide to form the α‐furan ketone with the desired configuration.     

Simple,Efficient, and Catalyst‐Free Synthesis of (2‐Amino‐4H‐1‐benzopyran‐4‐yl)phosphonates in Polyethylene Glycol

Several (2‐amino‐4H‐1‐benzopyran‐4‐yl)phosphonates were efficiently synthesized by employing a multicomponent protocol involving a salicylaldehyde, malononitrile or ethyl cyanoacetate, and a trialkyl phosphite in polyethylene glycol. The latter could be recovered and re‐used. No additional solvent or catalyst was required. To the best of our knowledge, this is the first report of the one‐pot preparation of (2‐amino‐4H‐1‐benzopyran‐4‐yl)phosphonic acid dimethyl esters.     

Copper‐Free Huisgen Cycloaddition for the 14‐3‐3‐Templated Synthesis of Fusicoccin‐Peptide Conjugates

Mid‐sized molecules have emerged as an attractive chemical space and potentially provide a robust basis for the development of synthetic agents to control intracellular protein interactions. However, the limited cell permeability and chemical tractability of such agents remain to be addressed. We envisioned that target‐templated synthesis of such mid‐sized molecules might provide a solution. Here, we exploited a copper‐free Huisgen cycloaddition for template synthesis using a peptide fragment containing a 4,8‐diazacyclononyne (DACN) moiety and an azide‐containing fusicoccin derivative in the presence or absence of recombinant 14‐3‐3ζ protein in vitro. Time‐course changes in the yield of products demonstrated that the reaction was accelerated in the presence of 14‐3‐3 and one of the regioisomers was generated predominantly, supporting the template effect.     

Metal‐Free Multicomponent Synthesis of (α‐Aminoalkyl)phosphonates Using 2,4,6‐Trichloro‐1,3,5‐triazine

(α‐Aminoalkyl)phosphonates have efficiently been synthesized by multicomponent reaction of aldehydes, amines, and triethyl phosphite in the presence of 2,4,6‐trichloro‐1,3,5‐triazine at room temperature. The products are formed in high yields (83–91%) within 0.5–1 h.     

Sulfenylation of heterocyclic 1,3‐dicarbonyl systems: 4‐Hydroxy‐2‐pyrones, 6‐hydroxy‐4‐pyrimidones, 4‐hydroxy‐2‐pyridones, 4‐hydroxy‐6‐pyridazinones,and 5‐hydroxy‐3‐pyrazolones

Anions of enolized heteroaromatic 1,3‐dicarbonyl systems, such as the title compounds 1, 9,14 , and 19 , react in dimethylformamide in the presence of potassium carbonate with diaryl disulfides 2 to yield arylsulfenyl derivatives ( 3, 10, 15, 20 ). The arylthiolate anions 4 formed in this reaction can be oxidized by air to yield the starting disulfides 2 again. Tetraalkylthiuram disulfides 7 react in the same manner to yield dialkylaminothiocarbonylthio derivatives ( 8, 13, 18 ) of the title compounds. Oxidation of the arylsulfenyl derivatives with hydrogen peroxide in sodium hydroxide solution usually leads to sulfoxides ( 5, 11, 16 ), whereas oxidation with peracetic acid affords sulfones ( 6, 12, 17 ).     

Metal‐Free σ‐Bond Metathesis in 1,3,2‐Diazaphospholene‐Catalyzed Hydroboration of Carbonyl Compounds

The first metal‐free catalytic hydroboration of carbonyl derivatives has been developed in which a catalytic amount of 1,3,2‐diazaphospholene effectively promotes a hydroboration reaction of aliphatic and aromatic aldehydes and ketones. The reaction mechanism involves the cleavage of both the P? O bond of the alkoxyphosphine intermediate and the B? H bond of pinacolborane as well as the formation of P? H and B? O bonds. Thus, the reaction proceeds through a non‐metal σ‐bond metathesis. Kinetic and computational studies suggest that the σ‐bond metathesis occurred in a stepwise but nearly concerted manner.     

Metal‐Free Photochemical Aromatic Perfluoroalkylation of α‐Cyano Arylacetates

We report here an operationally simple protocol for the direct aromatic perfluoroalkylation and trifluoromethylation of α‐cyano arylacetates. This metal‐free approach, which occurs at ambient temperature and under visible‐light irradiation, is driven by the photochemical activity of electron donor–acceptor (EDA) complexes, formed in situ by the interaction of transiently generated enolates and perfluoroalkyl iodides. Preliminary mechanistic studies are reported.