Synthesis and activity in enhancing long-term potentiation (LTP) of clausenamide stereoisomers

Palladium Catalysis Enabled Sequential C(sp3)-H/C-C Activation: Access to Vinyl γ-Lactams

A Pd(II)-catalyzed tandem reaction of aliphatic amides with vinylcyclopropanes (VCPs) was accomplished by merging C(sp3)-H and C-C activation. The reaction of VCP revealed alkenylation/cyclization, followed by ring opening via C-C cleavage, delivering vinyl γ-lactams with (E)-selectivity. The role of ligands, site-selectivity, functional group diversity, mechanistic insight, and synthetic utilities are important practical features.

Comparative Analysis of Phytochemical Profiles and Antioxidant Activities between Sweet and Sour Wampee (Clausena lansium) Fruits

As a local medicine and food, wampee fruit, with abundant bioactive compounds, is loved by local residents in Southern China. Titratable acid (TA), total sugar (TS), and total phenolic and flavonoid contents were detected, and phytochemical profiles and cellular antioxidant activities were analyzed by the HPLC and CAA (cellular antioxidant activity) assay in five sweet wampee varieties and five sour wampee varieties. Results showed that the average TS/TA ratio of sweet wampee varieties was 29 times higher than sour wampee varieties, while TA content was 19 times lower than sour wampee varieties. There were much lower levels of total phenolics, flavonoids, and antioxidant activities in sweet wampee varieties than those in sour wampee varieties. Eight phytochemicals were detected in sour wampee varieties, including syringin, rutin, benzoic acid, 2-methoxycinnamic acid, kaempferol, hesperetin, nobiletin, and tangeretin, while just four of them were detected in sweet wampee varieties. Syringin was the only one that was detected in all the sour wampee varieties and was not detected in all sweet wampee varieties. Correlation analysis showed significant positive correlations between TA with phenolics, flavonoids, and total and cellular (PBS wash) antioxidant activities, while there were significant negative correlations between TS/TA with phenolic and cellular (no PBS wash) antioxidant activities. This suggested that the content of titratable acid in wampee fruit might have some relationship with the contents of phenolics and flavonoids. Sour wampee varieties should be paid much attention by breeders for their high phytochemical contents and antioxidant activities for cultivating germplasms with high health care efficacy.

Multicomponent Synthesis of Unsaturated γ-Lactam Derivatives. Applications as Antiproliferative Agents through the Bioisosterism Approach: Carbonyl vs. Phosphoryl Group

We report efficient synthetic methodologies for the preparation of 3-amino and 3-hydroxy 3-pyrrolin-2-ones (unsaturated γ-lactams) through a multicomponent reaction of amines, aldehydes and acetylene or pyruvate derivatives. The densely substituted γ-lactam substrates show in vitro cytotoxicity, inhibiting the growth of the carcinoma human tumor cell lines RKO (human colon epithelial carcinoma), SKOV3 (human ovarian carcinoma) and A549 (carcinomic human alveolar basal epithelial cell). In view of the possibilities for the diversity of the substituents that offer a multicomponent, synthetic methodology, an extensive structure–activity profile is presented. In addition, the bioisosteric replacement of the flat ester group by a tetrahedral phosphonate or phosphine oxide moiety in γ-lactam substrates leads to increased growth inhibition activity. Cell morphology analysis and flow cytometry assays indicate that the main pathway by which our compounds induce cytotoxicity is based on the activation of the intracellular apoptotic mechanism.

Direct Transformation of N-Protected α,β-Unsaturated γ-Amino Amides into γ-Lactams through a Base-Mediated Molecular Rearrangement

Here, we are reporting a single-step transformation of N-protected α,β-unsaturated γ-amino amides into 5,5-disubstituted γ-lactams through a base-mediated new molecular rearrangement. In contrast to the known N- to C(O) cyclization of saturated γ-amino acids into corresponding γ-lactams, the new rearrangement involves the cyclization between N-terminal C^γ- to C-terminal amide N. The cyclization process was initiated by the migration of double bond from α,β → β,γ position. The enamine-imine tautomerization of the new β,γ-double bond and subsequent 5-exo-trig cyclization of terminal amide leads to the formation of N-protected 5,5-disubstituted γ-lactam. The structures of various γ-lactams obtained from the rearrangement were studied in single crystals. Overall, the results reported here demonstrate the facile and single-step transformation of N-protected α,β-unsaturated γ-amino amides into γ-lactams and provided an excellent opportunity to construct small-molecule peptidomimetics.

Asymmetric Synthesis of Enantioenriched 6-Hydroxyl Butyrolactams Promoted by N-Heterocyclic Carbene

Herein, an efficient route to synthesize 6-hydroxyl butyrolactams has been successfully developed via an N-heterocyclic carbene-catalyzed formal [3 + 2] annulation of bromoenals with α-amino ketones, followed by reduction. Remarkably, enantioenriched epi-neoclausenamide, which is one of the clausenamide derivatives, could be efficiently prepared by this strategy.

Oxidative cross-dehydrogenative [2 + 3] annulation of α-amino ketones with α-keto esters: concise synthesis of clausenamide analogues

A one-pot oxidative cross-dehydrogenative [2 + 3] annulation of α-amino ketones with α-keto esters at room temperature is reported.

Physiological signature of a novel potentiator of AMPA receptor signalling

We have synthesized a novel small molecule based on the pyrrolidinone–containing core structure of clausenamide, which is a candidate anti–dementia drug. The synthetic route yielded multi–gram quantities of an isomeric racemate mixture in a short number of steps. When tested in hippocampal slices from young adult rats the compound enhanced AMPA receptor–mediated signalling at mossy fibre synapses, and potentiated inward currents evoked by local application of l–glutamate onto CA3 pyramidal neurons. It facilitated the induction of mossy fibre LTP, but the magnitude of potentiation was smaller than that observed in untreated slices. The racemic mixture was separated and it was shown that only the (−) enantiomer was active. Toxicity analysis indicated that cell lines tolerated the compound at concentrations well above those enhancing synaptic transmission. Our results unveil a small molecule whose physiological signature resembles that of a potent nootropic drug.

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A small molecule was developed using a novel approach towards the synthesis of clausenamide, which is thought to have anti–dementia properties.

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When tested in hippocampal slices the compound enhanced AMPA receptor signalling as well as glutamate–evoked currents in CA3 pyramidal neurons.

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It facilitated the induction of mossy fibre LTP.

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Cytotoxicity experiments revealed no deleterious effect to cells at sub–millimolar concentrations.

Synthesis of Highly Substituted 3-Pyrrolin-2-ones from N,N-Disubstituted α-Amino Acids

Highly functionalized 5-membered N-heterocyclic compounds, 4-aryl-3-chloro-5-methoxy-1-methyl-3-pyrrolin-2-ones, have been synthesized in moderate to high yields by the reaction of N,N-dimethylated aromatic α-amino acids with oxalyl chloride, followed by solvolysis with MeOH. The products possess a number of functional groups such as an amide, a mixed amido/alkoxy acetal, a vinyl halide, and an alkene and thus are promising candidates to be used as starting materials for the synthesis of diverse five-membered N-heterocyclic compounds.

Biologically active γ-lactams: synthesis and natural sources

The γ-lactam moiety is present in a large number of natural and non-natural biologically active compounds. The range of biological activities covered by these compounds is very broad. Functionalized γ-lactams are thus of high interest and have great potential in medicinal chemistry. This review provides a description of the title compounds by focusing on their synthesis, natural sources and biological activities.

γ- and δ-Lactams from the Leaves of Clausena lansium

Eight new clausenamides, including three γ-lactams (1-3), four δ-lactams (4-7), and an amide (8), and seven known lactams, including compounds 9-11, which were purified from natural sources for the first time, were characterized from the leaves of Clausena lansium. Their structures were elucidated using spectroscopic methods, and the absolute configurations were determined using electronic circular dichroism and single-crystal X-ray diffraction analyses with Cu Kα radiation. Compound 2 (50 μM) protected 22.24% of cortical neurons against Aβ25-35-induced cell death.

An investigations on the molecular structure, FT-IR, FT-Raman and NMR spectra of 1-(p-tolylsulfonyl) pyrrole by theoretical and experimental approach

Fourier-Transform-Infrared, Fourier-Transform-Raman and Nuclear Magnetic Rezonans spectra of 1-(p-tolylsulfonyl) pyrrole molecule have been recorded. In the powder form, vibrational spectra of 1-(p-tolylsulfonyl) pyrrol molecule were investigated in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. The conformational analysis, geometrical structure, molecular electrostatic potential map, HOMO-LUMO and vibrational spectroscopic properties of the isolated 1-(p-tolylsulfonyl) pyrrole molecule have also been carried out at the Molecular Mechanic and Density Functional Theory approaches. Density Functional Theory results have been associated with Scaled Quantum Mechanics Force Field for fitting between the theoretical and the experimental frequencies.

Maltose, A Natural, Efficient and Economical Catalyst for the One-Pot Synthesis of Highly Substituted Dihydropyrrol-2-Ones

Maltose is a natural, economical and very effective catalyst for promotion of the four-component domino reaction between amines, dialkyl acetylenedicarboxylates and formaldehyde to afford substituted dihydropyrrol-2-ones at room temperature. The advantages of this protocol are good yields, short reaction times, low cost, environmentally friendly, simple work-up and lack of need for column chromatography.

A One-pot Multi-component Synthesis of N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates Catalysed by Oxalic Acid Dihydrate

A simple synthesis of N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates via one-pot multi-component reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in the presence of oxalic acid dihydrate (20 mol%) as catalyst in methanol is described. This homogeneous catalytic procedure offers advantages including mild reaction conditions, good to high yields, short reaction time, simple and readily available starting materials, easy work-up and there is no need for column chromatography.

Approach to the library of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones through a three-component condensation

A convenient procedure for the parallel synthesis of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones through a three-component condensation of active methylene compounds, aldehydes, and amines was developed. It was shown that the use of acetic acid as the reaction medium was suitable for the considerably reactive substrates with no additional functionalities. The substrates with low reactivity and those possessing carboxylic groups or additional basic centers required the use of DMF as the solvent and chlorotrimethylsilane as the reaction promoter was necessary. More than 3000 pyrrolones were synthesized by the developed procedure. To demonstrate the scope of the described approach 114 library representatives were fully characterized.

Synthesis of N-substituted Clausenamide analogues

A practical synthesis of N-substituted Clausenamide analogues, including (-) and (+) CM1, Piracetam analogue 1 and Nefiracetam analogue 2, have been developed.