Synthesis and Evaluation of Efavirenz (SustivaTM) Analogues as HIV-1 Reverse Transcriptase Inhibitors: Replacement of the Cyclopropylacetylene Side Chain

Convenient synthesis of N-alkyl-3,1-benzoxazin-2-ones from carbamate protected anthranil aldehydes and ketones via one-step alkylation/alkoxy rearrangement

A practical and step-economical protocol was developed to prepare N-alkyl-3,1-benzoxazin-2-one derivatives from anthranil aldehydes and ketones via one-step alkylation/alkoxy rearrangement, where three new chemical bonds and one ring were constructed in a single step. Control studies revealed a stepwise mechanism and that the alkoxy rearrangement was an intermolecular process.

Iridium-Catalyzed Intramolecular Asymmetric Allylation of Vinyl Benzoxazinones for the Synthesis of Chiral 4H-3,1-Benzoxazines via Kinetic Resolution

Chiral benzoxazinones and 4H-3,1-benzoxazines as important motifs are widely found in abundant pharmaceuticals and biological molecules. We herein successfully developed the first kinetic resolution (KR) process of racemic benzoxazinones through Ir-catalyzed asymmetric intramolecular allylation, furnishing a wide range of chiral benzoxazinones and 4H-3,1-benzoxazines with excellent results via outstanding KR performances (with the s factor up to 170). This protocol exhibited broad substrate scope generality and good functional group tolerance, and the chiral 4H-3,1-benzoxazine products could be readily transformed to other useful optically active heterocycles.

Construction of Diverse N-Heterocycles by Formal (3 + 3) Cycloaddition of Naphthol/Thionaphthol/Naphthylamine and 1,3,5-Triazinanes

Here, we report a facile and metal-free method for the construction of dihydrooxazine derivatives via a formal (3 + 3) annulation reaction of naphthols and 1,3,5-triazinanes. The 1,3,5-triazinanes were utilized as a formal three-atom synthon (C-N-C) for cycloaddition. In addition, dihydrothiazine and tetrahydrobenzoquinazoline derivatives could also be produced in good yields by this strategy under catalyst-free and additive-free conditions.

One-pot synthesis of naphtho[1,2-e][1,3]oxazines in the presence of FNAOSiPAMP*/CuII as an almond shell based nanocatalyst

In the present research work, a novel catalyst based on natural material, namely, Fe₃O₄@nano-almondshell@OSi(CH₂)₃/NHCH₂pyridine/Cu^II abbreviated (FNAOSiPAMP/Cu^II) was designed and prepared. The properties of the catalyst was identified by Fourier-transform infrared spectroscopy (FT-IR), Thermogravimetry ananlysis (TG), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), and Mapping. Furthermore, the evaluation of catalytic activity was done in the course of naphtho-1,3-oxazines synthesis. Solvent-free conditions, simplicity of operation, easy work-up and use of an eco-friendly catalyst are some of advantages of this protocol.

α-C–H functionalization of tertiary amines catalyzed/promoted by molecular iodine/derivatives

A recent review on the α-C–H functionalization of tertiary amines using low-cost and benign I₂ or its derivatives.

Gum arabic-OPO3H2 as a new natural-based green catalyst for the one-pot pseudo-four-component synthesis of naphtho[1,2-e][1,3]oxazines

Gum arabic-OPO₃H₂ (GA-OPO₃H₂) as a unique natural-based green catalyst was synthesized by the reaction of phosphorus pentoxide with gum arabic. The structure and properties of the catalyst were studied via several analysis methods such as FT-IR, MAPPING, EDS, SEM, XRD, and TGA. The efficiency of the above-mentioned catalyst was investigated for the synthesis of naphtho-1,3-oxazines via a pseudo-four-component reaction of primary amines, formaldehyde, and 2-naphthol under the solvent-free grinding condition at room temperature using an electrical mortar-heater. The obtained results indicated that GA-OPO₃H₂ is a highly efficient green catalyst for the synthesis of naphtho[1,2-e][1,3]oxazines with high yields, simple workup, and benign reaction condition.

Gum arabic-OPO₃H₂ (GA-OPO₃H₂) as a unique natural-based green catalyst was synthesized by the reaction of phosphorus pentoxide with gum arabic.

Recent advances in intramolecular C–O/C–N/C–S bond formationviaC–H functionalization

This review presents the construction of C–X bonds (X = O/N/S) by using intramolecular C–H functionalization for the synthesis of heterocyclic compounds.

One-pot solvent-free synthesis of 2,3-dihydro-2-substituted-1H-naphtho[1,2-e][1,3]oxazine derivatives using Fe3O4@nano-cellulose/TiCl as a bio-based and recyclable magnetic nano-catalyst

The present study describes an efficient and environmentally benign protocol for the synthesis of 2,3-dihydro-2-substituted-1H-naphtho[1,2-e][1,3]oxazine derivatives. Synthesis is done by one-pot three-component condensation of 2-naphthol, formaldehyde, and primary amines in the presence of Fe₃O₄@nano-cellulose/TiCl as a bio-based magnetic nano-catalyst under solvent-free conditions at room temperature grinding. This green procedure offers the advantages of high yield, short reaction time, environmental friendliness, easy workup, simple magnetic recovery of the catalyst and its reusability up to ten times without significant loss of catalytic activity. The structure of products was approved by FT-IR, ¹H-NMR, ¹³C-NMR spectroscopy.

Synthesis and Fungicidal Activity of 1-(Carbamoylmethyl)-2-aryl-3,1-benzoxazines

A series of new 1-(carbamoylmethyl)-2-aryl-3,1-benzoxazines were prepared in moderate to good yields by BF₃·OEt₂-catalyzed reactions of aromatic aldehydes with 2-(N-substituted carbamoylmethylamino)benzyl alcohols. The structures of the target compounds were confirmed by IR, ¹H-NMR, ¹³C-NMR, and elemental analyses. The fungicidal activities of the target compounds against plant fungi were preliminarily evaluated, and some of them exhibited good activity.

Preparing Mn(iii) salen-type Schiff base complexes using 1,3-oxazines obtained by Mannich condensation: towards removing ortho-hydroxyaldehydes

Synthesis of Mn(iii)-salen type Schiff base complexes from 1,3-oxazines obtained from Mannich condensation. This method eliminates the restrictions on the use ofortho-hydroxyaldehydes.

Medicinal applications of perfluoroalkylated chain-containing compounds

Compounds with polyfluorinated molecular fragments possess unique properties associated with the presence of a large number of fluorine atoms that affect lipophilicity and conformational rigidity of the parent molecule along with other effects. The aim of this review is to provide an overview of synthesized compounds possessing perfluoroalkylated or polyfluorinated chains that have been tested for bioactivity or as potential drug candidates for the treatment of various diseases. As far as the length of the perfluoroalkylated chain is concerned the focus is centered on the compound bearing perfluoroethyl or tetrafluoroethyl as well as longer chains. The perfluoroalkylated compounds discussed are classified according to their biological activity.

Redox-neutral α-oxygenation of amines: reaction development and elucidation of the mechanism

Cyclic secondary amines and 2-hydroxybenzaldehydes or related ketones react to furnish benzo[e][1,3]oxazine structures in generally good yields. This overall redox-neutral amine α-C-H functionalization features a combined reductive N-alkylation/oxidative α-functionalization and is catalyzed by acetic acid. In contrast to previous reports, no external oxidants or metal catalysts are required. Reactions performed under modified conditions lead to an apparent reductive amination and the formation of o-hydroxybenzylamines in a process that involves the oxidation of a second equivalent of amine. A detailed computational study employing density functional theory compares different mechanistic pathways and is used to explain the observed experimental findings. Furthermore, these results also reveal the origin of the catalytic efficiency of acetic acid in these transformations.

Synthesis of meso-substituted dihydro-1,3-oxazinoporphyrins

Novel dihydro-1,3-oxazinoporphyrins and naphtho[e]bis(dihydro-1,3-oxazinoporphyrin) derivatives, in which the porphyrin macrocycle is covalently linked to the dihydro-1,3-oxazine ring system were successfully synthesized from 5-(4-aminophenyl)-10,15,20-triphenylporphyrin in good yields. The structures of the target products were established on the basis of spectral data and elemental analyses.

Looking for an active conformation of the future HIV type-1 non-nucleoside reverse transcriptase inhibitors

HIV type-1 (HIV-1) non-nucleoside reverse transcriptase inhibitors (NNRTIs) are key drugs of highly active antiretroviral therapy (HAART) in the clinical management of AIDS/HIV infection. NNRTI-based HAART regimes effectively suppress viral reproduction, are not cytotoxic and show favourable pharmacokinetic properties. First-generation NNRTIs suffer the rapid selection of viral variants, hampering the binding of inhibitors into the reverse transcriptase (RT) non-nucleoside binding site (NNBS). Efforts to improve these first inhibitors led to the discovery of second-generation NNRTIs that proved to be effective against the drug-resistant mutant HIV-1 strains. The success of such agents launched a new season of NNRTI design and synthesis. This paper reviews the characteristics of second-generation NNRTIs, including etravirine, rilpivirine, RDEA-806, UK-453061, BIRL 355 BS, IDX 899, MK-4965 and HBY 097. In particular, the binding modes of these inhibitors into the NNBS of the HIV-1 RT and the most clinically relevant mutant RTs are analysed and discussed.