Extrusion Reaction Research Articles

ChemInform Abstract: Recent Progress in the Chemistry of Supercarboranes

AbstractReview: about 50 refs.

ChemInform Abstract: Evidence for Phthalimidonitrene as a Common Intermediate in Several Extrusion Reactions.

A common intermediate, presumably phthalimidonitrene 1, is generated in the thermolysis of the aziridinobenzofurans 3(R = Ac, CO2Me, Bz, COBut and CN) as well as the sulphimide 4, and the azabenzonorbornadiene 5. The transfer of 1 shown in Scheme 1 is zero order in 2-acetylbenzofuran providing further evidence against a concerted bimolecular mechanism 10 for ‘nitrene’ transfer.

ChemInform Abstract: Cycloaddition of Chlorosulfonyl Isocyanate to 2H-Azirines: Formation of (2+2+2)Cycloadducts.

Abstract Chlorosulfonyl isocyanata (CSI) reacts with 2H-azirines 1 a-c at -78°C to form [2+2+2] cycloadducts 3a-c and 4a-c. The tricyclic aziridine derivatives 4a-c undergo CSI extrusion reactions and subsequent oxidation to the corresponding pyrazines 5a-c. Structural identifications of 3a-c and 4a-c are based on ir, nmr and mass spectral data.

ChemInform Abstract: Synthesis, Conformation, and the Stereoselective Sulfur Extrusion Reaction of a New Intraannular Dibromo-Substituted Tetrathia(4.4)metacyclophane.

The oxidative coupling of 2,6-bis(mercaptomethyl)bromobenzene using I2 gave syn- and anti-10,20-dibromo-2,3,12,13-tetrathia[4.4]metacyclophane (1) which can be isolated in the solid state at room temperature. The sulfur extrusion reaction of anti-1with (Et2N)3P afforded the corresponding dithia[3.3]metacyclophane, while syn-1 gave the trithia[3.4]metacyclophane.

Meso-Trifluoromethyl-substituted Subporphyrin from Ring-splitting Reaction of meso-Trifluoromethyl-substituted [32]Heptaphyrin(1.1.1.1.1.1.1)

Abstract meso-Trifluoromethyl-substituted subporphyrin was obtained through an extrusion reaction from meso-trifluoromethyl-substituted heptaphyrin(1.1.1.1.1.1.1) upon combined metallation of Cu(II) and B(III) ions. The subporphyrin exhibited the most blue-shifted Soret-like absorption band among those ever prepared.

Chemoselectivity of the Reactions of Diazomethanes with 5‐Benzylidene‐3‐phenylrhodanine

AbstractThe reactions of 5‐benzylidene‐3‐phenylrhodanine (2; rhodanine=2‐thioxo‐1,3‐thiazolidin‐4‐one) with diazomethane (7a) and phenyldiazomethane (7b) occurred chemoselectively at the exocyclic CC bond to give the spirocyclopropane derivatives 9 and, in the case of 7a, also the C‐methylated products 8 (Scheme 1). In contrast, diphenyldiazomethane (7c) reacted exclusively with the CS group leading to the 2‐(diphenylmethylidene)‐1,3‐thiazolidine 11 via [2+3] cycloaddition and a ‘two‐fold extrusion reaction’. Treatment of 8 or 9b with an excess of 7a in refluxing CH2Cl2 and in THF at room temperature in the presence of [Rh2(OAc)4], respectively, led to the 1,3‐thiazolidine‐2,4‐diones 15 and 20, respectively, i.e., the products of the hydrolysis of the intermediate thiocarbonyl ylide. On the other hand, the reactions with 7b and 7c in boiling toluene yielded the corresponding 2‐methylidene derivatives 16, 21a, and 21b. Finally, the reaction of 11 with 7a occurred exclusively at the electron‐poor CC bond, which is conjugated with the CO group. In addition to the spirocyclopropane 23, the C‐methylated 22 was formed as a minor product. The structures of the products (Z)‐8, 9a, 9b, 11, and 23 were established by X‐ray crystallography.

Synthesis and chemical structure of natural rubber adduct with SO 2 and study of the thermal stability

Natural rubber (NR, cis-1,4-polyisoprene) was reacted in solution with SO 2 at room temperature in different solvents (tetrahydrofuran, CHCl 3, CH 2Cl 2 and tetralin). The reaction product consisted of an adduct between NR and SO 2. The chemical structure of the adduct was studied by FT-IR spectroscopy, by thermogravimetry coupled with FT-IR (TGA–FT-IR), by differential thermal analysis (DTA) and by derivative thermogravimetry (DTG). The maximum SO 2 uptake from NR was 21% as determined by TGA. The TGA of the NR–SO 2 shows that the adduct decomposes in two steps initially releasing SO 2 at lower temperature and then decomposing at higher temperature like common NR. It is proposed that the chemical structure of the NR–SO 2 adduct consists of SO 2 molecules added to the double bonds of the isoprene units forming a sulfone derivative with three-membered rings known as thiirane-1,1-dioxide. On heating the thiirane ring decomposes releasing SO 2 in an extrusion reaction giving back the NR macromolecule. The possible potential applications of the NR–SO 2 adduct which is cheap and easy to prepare are outlined.

Novel 3,4-Diazabenzotropone Compounds (2,3-Benzodiazepin-5-ones): Synthesis, Unique Reactivity, and Biological Evaluation

Efficient synthesis of 3,4-diazabenzo[b]tropone was first achieved utilizing 4pi-8pi sequential electrocyclic reactions of functionalized benzocyclobutenone derivatives. These compounds are highly electron deficient and readily form amine adducts at ambient temperature. Furthermore, gentle heating resulted in quantitative nitrogen extrusion to produce indenone derivatives. These diazabenzotropones were found to exhibit potent apoptosis-inducing activity against human lymphoma cells. Thus, novel amine-catalyzed nitrogen extrusion reactions and interesting bioactivities were found to be characteristic of these novel diazabenzotropone compounds.

ChemInform Abstract: SO2‐Extrusion Reactions of Sulfonylated Nucleosides: A Novel Strategy for the Synthesis of Exocyclic Olefinic Thymidines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

SO2-Extrusion Reactions of Sulfonylated Nucleosides: A Novel Strategy for the Synthesis of Exocyclic Olefinic Thymidines

Analogues of 3′-C-methylidene-2′,3′-dideoxy-5-meth­yluridine have been synthesized from the 3′-deoxy-3′-sulfonylated derivatives of thymidine using sulfur dioxide extrusion reaction.

Shining Light on Dinitrogen Cleavage: Structural Features, Redox Chemistry, and Photochemistry of the Key Intermediate Bridging Dinitrogen Complex

The key intermediate in dinitrogen cleavage by Mo(N[t-Bu]Ar)3, 1 (Ar = 3,5-C6H3Me2), has been characterized by a pair of single crystal X-ray structures. For the first time, the X-ray crystal structure of (mu-N2)[Mo(N[t-Bu]Ar)3]2, 2, and the product of homolytic fragmentation of the NN bond, NMo(N[t-Bu]Ar)3, are reported. The structural features of 2 are compared with previously reported EXAFS data. Moreover, contrasts are drawn between theoretical predictions concerning the structural and magnetic properties of 2 and those reported herein. In particular, it is shown that 2 exists as a triplet (S = 1) at 20 degrees C. Further insight into the bonding across the MoNNMo core of the molecule is obtained by the synthesis and structural characterization of the one- and two-electron oxidized congeners, (mu-N2)[Mo(N[t-Bu]Ar)3]2[B(Ar(F))4], 2[B(Ar(F))4] (Ar(F) = 3,5-C6H3(CF3)2) and (mu-N2)[Mo(N[t-Bu]Ar)3]2[B(Ar(F))4]2, 2[B(Ar(F))4]2, respectively. Bonding in these three molecules is discussed in view of X-ray crystallography, Raman spectroscopy, electronic absorption spectroscopy, and density functional theory. Combining X-ray crystallography data with Raman spectroscopy studies allows the NN bond polarization energy and NN internuclear distance to be correlated in three states of charge across the MoNNMo core. For 2[B(Ar(F))4], bonding is symmetric about the mu-N2 ligand and the NN polarization is Raman active; therefore, 2[B(Ar(F))4] meets the criteria of a Robin-Day class III mixed-valent compound. The redox couples that interrelate 2, 2(+), and 2(2+) are studied by cyclic voltammetry and spectroelectrochemistry. Insights into the electronic structure of 2 led to the discovery of a photochemical reaction that forms NMo(N[t-Bu]Ar)3 and Mo(N[t-Bu]Ar)3 through competing NN bond cleavage and N2 extrusion reaction pathways. The primary quantum yield was determined to be Phi(p) = 0.05, and transient absorption experiments show that the photochemical reaction is complete in less than 10 ns.

ChemInform Abstract: A New Strategy Toward Fused‐Pyridine Heterocyclic Scaffolds: Bischler—Napieralski‐Type Cyclization, Followed by Sulfoxide Extrusion Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Subporphyrins: emerging contracted porphyrins with aromatic 14π-electronic systems and bowl-shaped structures: rational and unexpected synthetic routes

Subporphyrin is a ring-contracted porphyrin congener consisting of three pyrrolic subunits domed in a C3 symmetric bowl arrangement. Subporphyrin had long been elusive until the first synthesis of tribenzosubporphine in 2006. Shortly after, synthetic protocols of subpyriporphyrin, meso-aryl-substituted subporphyrins, and meso-aryl substituted subchlorins were developed. Subporphyrins display interesting properties including distinct aromaticity arising from 14pi-electronic conjugation, green fluorescence, and strong influences of meso-aryl substituents on the electronic network of the macrocycle. Besides the rational synthetic routes, an unexpected route to a specific subporphyrin from a [32]heptaphyrin(1.1.1.1.1.1.1) was discovered via a thermal extrusion reaction upon Cu(II)-B(III) cooperative metallation. In this Perspective, we review recent progress on subporphyrin chemistry and unprecedented ring-splitting reactions of medium size expanded porphyrins that are triggered upon metallation.

Multimetallocenes. A Theoretical Study

Quantum chemical calculations using gradient-corrected density functional theory at the BP86 level in conjunction with TZ2P basis sets have been carried out for the multimetallocenes CpMnCp, where M = Be, Mg, Ca, and Zn with n = 2−5. The equilibrium geometries and energetics with respect to loss of one metal atom are theoretically predicted. The nature of the metal−ligand interactions between the Mn2+ and (Cp-)2 moieties was investigated with energy decomposition analysis (EDA). The calculations predict that the CpMnCp species with n > 2 are thermodynamically unstable with respect to loss of one metal atom except for the beryllium compounds. The beryllocenes exhibit unusual stabilities in the gas phase for the whole series CpBenCp up to n = 5. The calculations suggest that the energy for loss of one metal atom from CpBe2Cp is significantly higher than from CpZn2Cp. The energy for the metal extrusion reaction of CpBe3Cp is much less endothermic than for CpBe2Cp but it is still more endothermic than the rea...

A New Strategy toward Fused-Pyridine Heterocyclic Scaffolds: Bischler−Napieralski-type Cyclization, Followed by Sulfoxide Extrusion Reaction

Method development was completed for a new strategy to obtain fused-pyridine heterocyclic scaffolds. The synthetic route entails a Bischler-Napieralski-type reaction as the key step, followed by a sulfoxide extrusion reaction. The reactions of 3-amino-2-arylthiopyridines or 3-amino-4-arylthiopyridines and carboxylic acids promoted by a Lewis acid such as SnCl4 yielded novel tricyclic pyridobenzothiazepines, which could be readily converted to their corresponding oxidized products via a sequence of sulfur oxidations and eventually to benzonaphthyridines via a sulfoxide extrusion. The synthetic strategy provides an efficient way to access libraries of novel structurally diversified heterocyclic compounds with potential pharmaceutical or biological activities.

Rapid Access to Pyrimido[5,4‐c]isoquinolines via a Sulfur Monoxide Extrusion Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Manifestations of the Alder−Rickert Reaction in the Structures of Bicyclo[2.2.2]octadiene and Bicyclo[2.2.2]octene Derivatives

The Alder-Rickert ethylene extrusion reaction manifests in the ground state structures of compounds 9-12 which contain the bicyclo[2.2.2]octadiene moiety and compounds 13, 14, and 17-20 which contain the bicyclo[2.2.2]octene moiety. A significant decrease of the 13C-13C one-bond coupling constants for the C-C bonds, which break in this fragmentation reaction, suggests lengthening, and hence weakening of these bonds. In the unsymmetrical systems these effects are also shown to be associated with strengthening of the CH2-CH2 bond, which is ultimately lost from the molecule as ethylene. Low-temperature crystal structures of compounds 9-12 and 16 provide evidence for similar crystal packing requirements of the CH2-CH2 and CH=CH moieties.

Rapid Access to Pyrimido[5,4-c]isoquinolines via a Sulfur Monoxide Extrusion Reaction

The scope of a sulfur monoxide extrusion reaction of pyrimido[4,5-b][1,4]benzothiazepines leading to pyrimido[5,4-c]isoquinolines was investigated. Thus, selective oxidation followed by nucleophilic displacement of the oxidized side chain sulfur group and subsequent extrusion reaction of sulfur monoxide in the ring, which can be conducted in a two-step sequence or in a one-pot procedure, produced novel pyrimido[5,4-c]isoquinolines, a class of compounds with potential biological and pharmaceutical applications. [reaction: see text].

Kinetics and Mechanism of the Thermolysis of 1,1-Dimethyl-1-germacyclohepta-2,4,6-triene

The thermolysis of 1,1-dimethyl-1-germacyclohepta2,4,6-triene led to the formation of benzene and dimethylgermylene, as expected. The activation energy and thermodynamic data for the germylene extrusion reaction were determined to be E a = 21.2 ± 0.1 kcal/mol, ΔH ‡ = 20.5 ± 0.1 kcal/mol, and ΔS ‡ = -8.1 ± 0.1 cal/(mol K), respectively.

Preparation of flame retardant polyamide 6 composite with melamine cyanurate nanoparticles in situ formed in extrusion process

This paper is focused on in situ preparation of melamine cyanurate (MCA) nanoparticles from reaction of melamine (MEL) and cyanuric acid (CA) and their flame retardant polyamide 6 (PA6) composite in the extrusion process through a novel reactive processing method. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were utilized to characterize the in situ formed MCA nanoparticles and their blends with PA6. Introduction of pentaerythritol (LTP) and water-bound plasticizer dioctyl phthalate (DPT) into the extrusion reaction system greatly inhibits the evaporation of water required for melamine and cyanuric acid reaction at high temperature (higher than 180 °C), laying a foundation for successful in situ preparation of MCA through reactive processing. XRD and FT-IR measurements indicate that under the effect of pentaerythritol, dioctyl phthalate and water, melamine really reacts with cyanuric acid to in situ form MCA in extrusion process. The reaction degree is close to 100%. A very important finding through SEM is that the in situ formed MCA particles, which were found to have aspect ratio of about 7.5, radial size in the range of 70–300 nm (mostly 70–90 nm) and crystallite size of less than 22 nm, are uniformly dispersed in the matrix PA6 at nanoscale. The in situ formed MCA nanoparticles greatly improve the flame retardancy and the mechanical properties of flame-retarded PA6 materials, and the introduced plasticizer dioctyl phthalate also ameliorates the related impact property. The obtained flame-retarded PA6 materials have good comprehensive performance with flame retardancy UL-94 V-0 rating at 1.6 and 3.2 mm thickness, tensile strength 48.0 MPa, elongation at break 106.3% and Izod notched impact strength 8.92 kJ/m 2. Compared with flame-retarded PA6 material with in situ formed MCA, the one prepared through conventional blending of PA6 with commercial MCA product has improved tensile strength but deteriorated impact strength and flame retardancy.