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December 2006
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55 Reads
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34 Citations
The Journal of Organic Chemistry
In this paper, we describe the synthesis of conformationally constrained cyclic peptides with biarylamine linkers for peptidomimetics using palladium-catalyzed intramolecular Buchwald-Hartwig C-N coupling. We have prepared a variety of di-, tri-, and tetrapeptides (16-22-membered) in good yields using this reaction.
May 2006
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21 Reads
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19 Citations
Tetrahedron Letters
In this letter, we report a palladium-catalyzed enyne cycloisomerization of linear peptides to generate small cyclic peptides embedded with a conjugated 1,3-diene. The utility of these resulting macrocyclic dienes is demonstrated by carrying out [4+2] cycloadditions with dienophiles to generate constrained cyclic peptides with cyclic linkers.
February 2006
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51 Reads
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89 Citations
Bioorganic & Medicinal Chemistry
2,4-Thiazolidinedione derivatives of 1,3-benzoxazinone were synthesized and evaluated for their PPAR-alpha and -gamma dual activation. DRF-2519, a compound obtained through SAR of TZD derivatives of benzoxazinone, has shown potent dual PPAR activation. In ob/ob mice, it showed better efficacy than the comparator molecules. In fat fed rat model, it showed significant improvement in lipid parameters, which was better than fibrates.
December 2005
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150 Reads
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42 Citations
The Journal of Organic Chemistry
[Reaction: see text]. Small peptides having a 3-bromobenzyl group at the C-termini and n-alkynoyl group at the N-termini undergo a smooth copper-free intramolecular Sonogashira coupling reaction to afford the corresponding cyclic peptides in moderate yields. Scope and limitations of this macrocyclization is demonstrated with di-, tri-, and tetrapeptides.
August 2005
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19 Reads
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15 Citations
Tetrahedron Letters
In this letter, we report that small peptides (di- and tri-) having a 3-bromobenzyl group at the C-termini and an acryloyl group at the N-termini undergo an efficient Bu3SnH–AIBN mediated intramolecular free radical cyclization to afford cyclic peptides in good yields. We also propose that these cyclizations are occurring via a pre-organized acyclic structure dictated by a reverse turn (γ/β-turn).
March 2005
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14 Reads
ACS National Meeting Book of Abstracts
October 2003
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319 Reads
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100 Citations
Bioorganic & Medicinal Chemistry Letters
Coumarin derivatives of different heterocycles (5,7a-i, 10 and 11) were designed based on cyclisation of 2-ethoxy-3-phenylpropanoic acid and 2-benzylmalonic acid as novel lipid-lowering agents and their preliminary in vivo screening indicates 7c has moderate triglyceride-lowering activity.
April 2003
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47 Reads
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39 Citations
Tetrahedron Letters
Tripeptides having a 3-bromobenzyl group at the C-termini and an acryloyl group at the N termini undergo efficient intramolecular Heck reactions to afford the corresponding cyclic peptides in good yields. Synthesis of two such peptides is discussed.
September 2002
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240 Reads
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76 Citations
Bioorganic & Medicinal Chemistry
A series of pyrimidinone derivatives of thiazolidinediones were synthesized. Their biological activity were evaluated in insulin resistant, hyperglycemic and obese db/db mice. In vitro PPARgamma transactivation assay was performed in HEK 293T cells. PMT13 showed the best biological activity in this series. PMT13 (5-[4-[2-[2-ethyl-4-methyl-6-oxo-1,6-dihydro-1-pyrimidinyl]ethoxy]phenylmethyl]thiazolidine-2,4-dione) showed better plasma glucose, triglyceride and insulin-lowering activity in db/db mice than rosiglitazone and pioglitazone. PMT13 showed better PPARgamma transactivation than the standard compounds. Pharmacokinetic study in Wistar rats showed good systemic exposure of PMT13. Twenty-eight day oral toxicity study in Wistar rats did not show any treatment-related adverse effects.
August 2001
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53 Reads
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97 Citations
European Journal of Medicinal Chemistry
We report here the synthesis of a series of 5-[4-[2-[substituted phthalazinones-2(or 4)yl]ethoxy]phenylmethyl]thiazolidine-2,4-diones and 5-[4-[2-[2,3-benzoxazine-4-one-2-yl]ethoxy]phenylmethyl]thiazolidine-2,4-diones and their plasma glucose and plasma triglyceride lowering activity in db/db mice. In vitro PPARgamma transactivation assay was performed in HEK 293T cells. In vitro and in vivo pharmacological studies showed that the phthalazinone analogue has better activity. PHT46 (compound 5a), the best compound in this series, showed better in vitro PPARgamma transactivation potential than troglitazone and pioglitazone. In insulin resistant db/db mice, PHT46 showed better plasma glucose and triglyceride lowering activity than the standard drugs. Pharmacokinetic study in Wistar rats showed good systemic exposure of PHT46. Subchronic toxicity study in Wistar rats did not show any treatment-related adverse effect.
... En completa analogía con los resultados reportados para la reacción catalizada por Pd, 22 una buena regioselectividad en la eliminación del β-hidruro en ausencia del ligando favorece la formación de 24a. Debe decirse que la reacción está limitada a los alquenos trisustituidos. ...
May 2006
Tetrahedron Letters
... 81 Ciclizações com Bu 3 SnH envolvendo ataque de radicais arila a um grupo alquenila vêm sendo amplamente utilizadas para a construção de ciclos de cinco e seis membros fundidos a anéis aromáticos 83 e a partir da década de 90 passaram a ser usadas também para a obtenção de ciclos com mais de seis membros fundidos a anéis benzênicos. 52,65,[84][85][86][87] Reação de bromoalil e bromobutenilcicloexanóis 48 e 49 (Esquema 29), respectivamente, com Bu 3 SnH, conduziu a compostos cíclicos fundidos a anéis aromáticos, por meio de ciclização 9-endo de radicais arila. 84 Por reação de iodobenzenos contendo uma cadeia derivada de aminoácido na posição orto com Bu 3 SnH foram obtidos compostos cíclicos de seis a nove membros, formados pelo modo endo 85 (Esquema 30). ...
August 2005
Tetrahedron Letters
... The helix-turn-helix (HTH) motif is instrumental to many DNA-binding proteins such as transcription factors that are capable of recognizing a particular DNA sequence for regulatory purposes [27]. To develop chemical probes gauging DNA-protein interactions, Iqbal et al. designed cyclic peptides bridged by a meta benzene ring such as 10 ( Figure 2A) [28]. As the final step of their synthesis, acyclic substrate 9 was treated with Pd(OAc) 2 , tri(o-tolyl)phosphine, and diisopropylethylamine in refluxing acetonitrile for 36 h. ...
April 2003
Tetrahedron Letters
... The phthalazin-1(2H)-one scaffold is one valuable diazaheterocyclic scaffold due to its wide pharmacological profile [1] as well as its applications in agrochemicals [2] and functional materials. [3] In particular, the phthalazin-1(2H)-ones bearing substitutions on C4-position display potent medicinal properties as anticancer, [4] antimicrobial, [5] anti-inflammatory, [6] antihypertensive, [7] antidiabetic [8] and neuroprotective [9] agents ( Figure 1). ...
August 2001
European Journal of Medicinal Chemistry
... Antidiabetic activity was explored against PPAR-γ. All the analogues 5-[4-(5-Methoxy-3-methyl-3H-imidazo [4,5-b] pyridin-2-ylmethoxy)benzyl]-thiazolidine-2,4-dione (36) showed significant antidiabetic activity on 3T3-L1 cell lines with 77% yield [41]. (43) showed prominent biological action against PPAR-γ cell lines, particularly on HEK 293T with a high 80% yield [42]. ...
September 2002
Bioorganic & Medicinal Chemistry
... Research has highlighted their potential in various therapeutic areas, including antitumor applications [30], photochemotherapy, anti-HIV activity [31], antibacterial and antifungal properties [32], anti-inflammatory effects [33], and anticoagulant activity through the inhibition of VKOR (vitamin K epoxide reductase) [34]. They also exhibit triglyceride-lowering effects [35] and act as central nervous system stimulants [36]. Hydroxycoumarins, in particular, are noted for their strong antioxidant capabilities, protecting against oxidative stress by neutralizing reactive oxygen species [37]. ...
October 2003
Bioorganic & Medicinal Chemistry Letters
... The chemistry of TZDs has gained prominence in recent years since these compounds have been discovered to have a variety of biological functions, such as antitumour [31], antiproliferative [32], cytotoxic [17], antihyperglycemics [33], antioxidant, anti-inflammatory, antimicrobial [34], neuroprotective, GSK-3 inhibitor [35], PPARγ agonist, dual PPARα/γ activator [36], dual inhibitor of the mitogenactivated protein kinase (Raf/MEK/ ERK) and the PI3K/ Akt signalling pathways, serine/threonine-protein kinases Pim-1 and Pim-2 inhibitor, Raf/MEK/ERK1/2 inhibitor [37]. Although all TZDs are PPAR ligands, genomic PPAR activation can only explain some of the observed anticancer effects. ...
February 2006
Bioorganic & Medicinal Chemistry
... Their incorporation in macrocyclic peptides, dipeptides and tripeptides is notable given their impor-tanceinm edicinal chemistry.T he incorporation of an alkynyl sulfidea dds an element of structuralr igidity to the macrocycles keletons pertinent to medicinal chemistry. [41] 2T herea re ample avenues for diversification through oxidation to incorporate sulfones, halide addition, or via cycloadditiont oa dd valuable fluorescenceq uenchers, amino acid or farnesylated appendages. Functionalization of other terminala lkynes is possible in an orthogonal manner to the alkynediyl sulfides, again provideavariety of options to modifyc yclic peptide frameworks. ...
December 2005
The Journal of Organic Chemistry
... 35 More recent reports by Planas and Feliu extended the scope of this reaction to SPPS. 36 Other Pd-catalyzed cross-couplings such the Sonogashira, 37,38 Heck, [39][40][41][42] Buchwald-Hartwig, 43,44 Stille 45 and Negishi 46 reactions have been also employed in peptide macrocyclization, with the group of Iqbal 38,42,43 providing various relevant examples. We chose to outline these results as they shed light onto the effect of the peptide structure on the ring-closing efficiency. ...
December 2006
The Journal of Organic Chemistry
