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1.
Purpose. To find out if the physical instability of a lyophilized dosage form is related to molecular mobility below the glass transition temperature. Further, to explore if the stability data generated at temperatures below the glass transition temperature can be used to predict the stability of a lyophilized solid under recommended storage conditions.
Methods. The temperature dependence of relaxation time constant, , was obtained for sucrose and trehalose formulations of the monoclonal antibody (5 mg protein/vial) from enthalpy relaxation studies using differential scanning calorimetry. The non-exponentiality parameter, , in the relaxation behavior was also obtained using dielectric relaxation spectroscopy.
Results. For both sucrose and trehalose formulations, the variation in with temperature could be fitted Vogel-Tammann-Fulcher (VTF) equation. The two formulations exhibited difference sensitivities to temperature. Sucrose formulation was more fragile and exhibited a stronger non-Arrhenius behavior compared to trehalose formulation below glass transition. Both formulations exhibited <2% aggregation at t values <10, where t is the time of storage.
Conclusions. Since the relaxation times for sucrose and trehalose formulations at 5°C are on the order of 108 and 106 hrs, it is likely that both formulations would undergo very little (<2%) aggregation in a practical time scale under refrigerated conditions. 相似文献
2.
Narenderreddy Katta Mamata Ojha Arumugavel Murugan Sagar Arepally Duddu S. Sharada 《RSC advances》2020,10(21):12599
The direct oxidative cleavage of activated alkynes via hydroamination has been described using organic photocatalyst under visible-light irradiation at room temperature. In this reaction, the single electron oxidation of an in situ formed enamine followed by radical coupling with an oxidant finally delivers the oxamate. The key features of this photocatalytic reaction are the mild reaction conditions, metal-free organic dye as a photocatalyst, and TBHP playing a dual role as “O” source and for the regeneration of the photocatalyst.The direct oxidative cleavage of activated alkynes via hydroamination has been described using organic photocatalyst under visible-light irradiation at room temperature. 相似文献
3.
Manickam Bakthadoss Jayakumar Srinivasan Mir Ashiq Hussain Duddu S. Sharada 《RSC advances》2019,9(42):24314
A new one pot assembly of highly functionalized benzo[a]phenazinone fused chromene/bicyclic scaffolds via a domino Knoevenagel intramolecular hetero-Diels–Alder (IMHDA) strategy using a solid state melt reaction (SSMR) of 2-hydroxynaphthalene 1,4-dione, o-phenylenediamine, O-allyl salicylaldehyde/O-vinyl salicylaldehyde derivatives is reported. The formation of five new bonds (two C–C bonds and three C–O bonds), three six-membered rings, and three stereogenic centers in a one-pot manner is very attractive. Ease of reaction with short time, good yields with water as the only byproduct and work up free procedure are some of the excellent features of the present protocol.A new one pot assembly of highly functionalized benzo[a]phenazinone fused chromene/bicyclic scaffolds via a domino Knoevenagel intramolecular hetero-Diels–Alder (IMHDA) strategy using a solid state melt reaction (SSMR) is reported.Multicomponent reactions (MCRs)1 are known to construct complex structures from simple starting materials in a rapid and highly efficient manner where the production of wastes is minimized. Those multicomponent reactions which are carried out in a ‘one-pot’ MC sequential manner provide a high degree of reaction mass efficiency, which is crucial in the development of modern synthetic methodology for drug discovery and pharmaceutical programs.2 Enormous work has been carried out in the field of multicomponent reactions in the past decade where several MCRs have been developed and extensively used in natural product synthesis and drug discovery. The Ugi reaction is a prime example of a four-component reaction that has been found to be a powerful and efficient method for the preparation of α-amino amides both in academia and industry.3 Therefore, the development of new MCRs for the synthesis of biologically active molecules continues to attract considerable attention for their atom- and step economy features.Heterocycles having nitrogen atom are widely available in nature and possess diverse and important biological activities.4 Phenazines are a group of organic compounds known to the mankind since past 150 years and are known to exhibit significant biological activities such as antimalarial, fungicidal, trypanocidal, antiplatelet, etc.5 A large number of drug molecules bearing the phenazine scaffold have been designed and evaluated in the recent years. The phenazines motif possess two dentate N atoms with three fused aromatic rings and an electron deficient conjugated system. The presence of the above features in phenazines give them an ability to form hydrogen bonds, ionic bonds, and π–π interactions with relative ease, and their use has also been demonstrated in supramolecular chemistry for molecular recognition (MR), supramolecular self-assembly (MS-A), and organic optic electronics materials.6 Few representative examples of phenazine and its derivatives are shown in the Fig. 1.Open in a separate windowFig. 1Some of naturally occurring phenazine derivatives.Chromenes and their derivatives are privileged scaffolds due to their ubiquitous presence in many natural products and synthetic molecules.7 Chromenes are also an important class of compounds displaying interesting biological activities against prostate cancer (DU-145) and breast cancer (MCF-7).8 Additionally, they have medicinal qualities such as antiviral and antimicrobial activity.9 Chromenes have also found their use in medicine, health-promoting agents, and photochromic materials.10In recent years, the domino-Knoevenagel-hetero-Diels–Alder reaction (DKHDA) which was extensively studied by Tietze''s group constitutes an important process for the preparation of complex compounds having interesting biological properties.11 The Diels–Alder reaction is important since it allows the formation of functionalized rings where there is complete control on regio-, diastereo-, and enantioselectivity. Moreover, the concerted nature of the Diels–Alder reactions allow the selective formation of up to three stereogenic centers in a single reaction step. Majority of the reactions reported on DKHDA have utilized 1,3-dicarbonyl compounds such as dimethyl barbituric acid, Meldrum''s acid and 1,3-indanedione.12 Additionally, other active methylene compounds like 1-phenyl-3-methyl pyrazolone, 4-hydroxy-coumarin, dihydroindole-2-thione, benzoylacetonitrile, 4-hydroxydithiocoumarin have been also used;13 but phenazinones have never been employed in DKHDA reactions. To the best of our knowledge, there are no reports on intramolecular DKHDA reactions using phenazinone as the coupling partner. Due to our interest in the construction of bioactive fused chromenophenazinone derivatives and since this molecule contains a 1,3-dicarbonyl as well as a 1,3-imine moiety, it would be very challenging to control the regioselectivity of the molecule; therefore phenazinone scaffold can act as a model substrate for an intramolecular DKHDA. We envisaged that a series of angular polycyclic chromeno fused phenazinone derivatives could be obtained and it is possible that the final hybrid compounds will result in being more selective and efficient than chromene and phenazinone compounds in biological assays.In this direction, we have decided to develop a new method for the preparation of novel benzo[a]phenazinone fused chromene/bicyclic scaffolds via a domino Knoevenagel intramolecular hetero-Diels–Alder (IMHDA) strategy using a solid state melt reaction (SSMR). As part of our research program for the development of new synthetic methods in heterocyclic chemistry14 and solid state melt reactions,15,16 we would like to report a simple and a general domino three-component reaction of 2-hydroxynaphthalene-1,4-dione, o-phenylenediamine and O-allylated/vinylated salicylaldehyde for the synthesis of pentacyclic benzo[a]phenazinone fused chromene/bicyclic scaffolds under environmentally benign reaction conditions (Scheme 1).Open in a separate windowScheme 1Synthetic approach to benzo[a]phenazinone fused chromenes.We have started this study by melting 2-hydroxynaphthalene-1,4-dione (2), o-phenylenediamine (1), and (E)-methyl 2-((2-formylphenoxy)methyl)-3-phenylacrylate (3) at 180 °C for 1 h in solvent free condition. Unfortunately, we could not obtain any desired product and the formation of a complex mixture was observed. To minimize the formation of the side products, the 2-hydroxynaphthalene-1,4-dione (2) and o-phenylenediamine (1) were first melted at 180 °C for 10 minutes to form the intermediate benzo[a]phenazin-5-ol. Subsequently, (E)-methyl 2-((2-formylphenoxy)methyl)-3-phenylacrylate 3a was added and the mixture was melted under the same temperature for 1 h which afforded the desired hybrid product chromene fused benzo[a]phenazinone 4a (ester moiety in ring junction) in 78% yield as shown in