Accelerating Effect of DMAP on CuI Catalyzed Buchwald‐Hartwig C‐N Coupling: Mechanistic Insight to the Reaction Pathway

Accessing Promising Passerini Adducts in Anticancer Drug Design

The 3-component Passerini reaction (3CPR), discovered little more than 100 years ago, has been demonstrated in the last few decades to be a valuable tool for accessing structural diversity and complexity, essential topics to consider in drug discovery programs. Focusing on accessing a fine-tuned family of α-acyloxyamide-oxindole hybrids, we underline herein our latest insights regarding the use of this mild reaction approach to obtain promising anticancer agents. Cheap and commercially available isatin was used as starting material. The library of α-acyloxyamide-oxindole hybrids was tested against six human solid-tumor cell lines; among them, non-small cell lung carcinoma, cervical and colon adenocarcinoma, and breast and pancreas cancer. The most potent compound displayed GI50 values in the range of 1.3-21 µM.

CuI/DMAP-Catalyzed Oxidative Alkynylation of 7-Azaindoles: Synthetic Scope and Mechanistic Studies

An efficient and practical method for the N-alkynylation of 7-azaindoles has been established by using CuI/DMAP catalytic system at room temperature and in open air. This simple protocol has been successfully employed in the synthesis of a wide range of N-alkynylated 7-azaindoles with good yields. Also, this approach is well-suited for large-scale N-alkynylation reactions. The designed N-alkynylated 7-azaindoles were further subjected to Cu-/Ir-catalyzed alkyne-azide cycloaddition (CuAAC/IrAAC) or "click" reaction for the rapid synthesis of 1,4-/1,5 disubstituted 1,2,3-triazole decorated 7-azaindoles. A mechanistic study based on density functional theory (DFT) calculations and ultraviolet-visible (UV) spectroscopic studies revealed that the CuI and DMAP combination formed a [CuII (DMAP)2 I2 ] species, which acts as an active catalyst. The DFT method was used to assess the energetic viability of an organometallic in the C-N bond formation pathway originating from the [CuII (DMAP)2 I2 ] complex. We expect that the newly designed Cu/DMAP/alkyne system will offer valuable insights into the field of Cu-catalyzed transformations.

Eco-Friendly Synthesis of Peptides Using Fmoc-Amino Acid Chlorides as Coupling Agent Under Biphasic Condition

BACKGROUND

Agro-waste derived solvent media act as a greener process for the peptide bond formation using N^α-Fmoc-amino acid chloride and amino acid ester salt with in situ neutralization and coupling under biphasic condition. The Fmoc-amino acid chlorides are prepared by the reported procedure of freshly distilled SOCl₂ with dry CH₂Cl₂. The protocol found many added advantages such as neutralization of amino acid ester salt and not required additional base for the neutralization, and directly coupling take place with Fmoc-amino acid chloride gave final product dipeptide ester in good to excellent yields. The protocol occurs with complete stereo chemical integrity of the configuration of substrates. Here, we revisited Schotten-Baumann condition, instead of using inorganic base.

OBJECTIVE

To develop green protocol for the synthesis of peptide bond using Fmoc-amino acid chloride with amino acid esters salt.

METHODS

The final product isolated is analyzed in several spectroscopic and analytical techniques such as FT-IR, ¹H-, ¹³C-NMR, Mass spectrometry and RP-HPLC to check stereo integrity and purity of the product.

CONCLUSION

The present method developed greener using natural agro-waste (lemon fruit shell ash) derived solvent medium for the reaction and not required chemical entity.