Publications by authors named "Sourabh Biswas"

This study presents a greener approach to the visible-light-induced micellar-catalyzed diastereoselective iodosulfonylation of cyclopropenes in a water medium. Remarkably, this process operates without a photocatalyst. Instead, it utilizes an electron-donor-acceptor complex formed between sulfonyl chloride and sodium iodide.

View Article and Find Full Text PDF

We have developed a tandem method essential for synthesizing sulfone-containing organic molecules, which has wide-ranging applications in agrochemicals, medicinal chemistry, and polymer science. This method involves a two-step process: an iodo-sulfonylated intermediate is formed initially, followed by elimination to regenerate the double bond, ultimately yielding sulfone-containing cyclopropenes. Control studies have confirmed the intermediacy of iodo-sulfonylated cyclopropane within the reaction sequence.

View Article and Find Full Text PDF

In this study, we have developed an effective and general strategy for synthesizing various 4-[(trifluoromethyl)thio]-2,3-dihydrofuran derivatives with high regioselectivity from easily prepared cyclopropyl ketone under mild reaction conditions. By the combination of photoredox, copper, and Lewis acid catalysis into a triple catalytic system, this methodology facilitates the selective cleavage of the carbon-carbon bonds and the formation of new carbon-oxygen and carbon-sulfur bonds. In addition, to enhance the synthetic feasibility of this protocol, we demonstrate its broad applicability across a wide range of substrates and its scalability for large-scale synthesis.

View Article and Find Full Text PDF

A highly adaptable method has been developed for the alkenylation of a broad spectrum of inert alkanes, employing milder reaction conditions. Tetrabutylammonium decatungstate (TBADT) serves as a photocatalyst for hydrogen atom transfer (HAT), instigating the formation of transient alkyl radicals through C(sp)-H functionalization. These radicals exhibit regioselective addition to cyclopropenes, followed by the subsequent activation of C-C bonds, forming the corresponding vinylated derivatives.

View Article and Find Full Text PDF

Rapid urbanization is a major cause of habitat and biodiversity loss and human-animal conflict. While urbanization is inevitable, we need to develop a good understanding of the urban ecosystem and the urban-adapted species, in order to ensure sustainable cities for our future. Scavengers play a major role in urban ecosystems, and often, urban adaptation involves a shift towards scavenging behaviour in wild animals.

View Article and Find Full Text PDF

Generating alkyl radicals from the sulfonyl radicals remains challenging in synthetic chemistry. Here, we report an efficient photocatalyzed strategy using alkyl sodium sulfinates as both sulfonylating and alkylating reagents by controlling the reaction temperature. This methodology provides a versatile protocol for synthesizing diastereoselective sulfonylated cyclopropanes and poly-substituted styrene derivatives.

View Article and Find Full Text PDF
Article Synopsis
  • The synthesis of tetra-substituted pyrazoles is achieved through a new method involving organo-photocatalyzed decarboxylative intramolecular cyclization using 1,2-diaza-1,3-dienes and α-ketoacids.
  • This method is notable for being metal-free and oxidant-free, which results in shorter reaction times and milder conditions.
  • The technique enhances the ability to create different pyrazole derivatives, broadening possibilities for future research and applications in various scientific areas.
View Article and Find Full Text PDF
Article Synopsis
  • A new strategy for hydroacylation of cyclopropene allows for creating various 2-acylcyclopropane compounds under mild conditions.
  • This method exhibits high tolerance for different functional groups and enables the production of acylated cyclopropanes in a controlled, diastereoselective way, utilizing photoinduced decarboxylation.
  • The regioselective addition of acyl radicals to the least substituted carbon enhances the method's potential for developing natural products.
View Article and Find Full Text PDF

Selective synthesis of three different bioactive heterocycles; isoxazolines, 5-hydroxy-2-isoxazolines and isoxazoles from the same starting material using TEMPO (2,2,6,6-Tetramethylpiperidin-1-oxyl) as a radical initiator is reported. Selectivity was achieved using different oxidants with TEMPO. The reaction goes through a 1,5-HAT (hydrogen atom transfer) process resulting in products with good yields.

View Article and Find Full Text PDF

Vascular endothelial growth factor A (VEGFA), which plays a key role in angiogenesis, is composed of many isoforms. Distinct VEGFA isoforms are generated by alternative splicing of VEGFA mRNA and named as VEGF, where represents the number of amino acids present in the final protein sequence. These isoforms have opponent pro- and antiangiogenic effects.

View Article and Find Full Text PDF

In this paper, the composition, structure, morphology and kinetics of evolution during isothermal oxidation of FeCrMoYCB metallic glass powder in the supercooled region are investigated by an integrated ex-situ and in-situ characterization and modelling approach. Raman and X-ray diffraction spectra established that oxidation yielded a hierarchical structure across decreasing length scales. At larger scale, FeO grows as a uniform shell over the powder core.

View Article and Find Full Text PDF