Article
Chemistry, Organic
Ganesh More, Pushpa Malekar, Rupali G. Kalshetti, Mahesh H. Shinde, Chepuri Ramana
Summary: This study demonstrates the Ru-catalyzed enantio- and diastereoselective dynamic kinetic resolution of alpha-(benzyloxy/benzoyloxy)acyl-gamma-butyrolactones via transfer hydrogenation. Excellent diastereo- and enantioselectivities were achieved with the in situ prepared (R,R)-Ru-FsDPEN catalyst, leading to the synthesis of important organic molecules with good efficiency.
TETRAHEDRON LETTERS
(2021)
Article
Chemistry, Organic
Pawan S. Dhote, Chepuri Ramana
Summary: The [Au]-catalyzed nitroalkyne cycloisomerization process leading to anthranils may be affected by the trapping of the postulated intermediate alpha-oxo gold carbene with external nucleophiles. This study also provides evidence for the synthesis of highly functionalized indazoles through sequential bond formations.
Article
Chemistry, Organic
Sibadatta Senapati, Nivedya A. Unmesh, Manoj N. Shet, Iram Ahmad, Nandu Ajikumar, Chepuri V. Ramana
Summary: This paper describes a highly diastereoselective total synthesis of several bis-THF C-15 acetogenin natural products, as well as the synthesis of an advanced intermediate reported in the total synthesis of (E/Z)-elatenynes. Key features in the synthesis include epoxide opening, Birch reduction, Sharpless asymmetric dihydroxylation-cycloetherification, S(N)2 halogenation, and a relay cross metathesis.
SYNTHESIS-STUTTGART
(2021)
Article
Chemistry, Multidisciplinary
Pawan S. Dhote, Swapnil V. Halnor, Chepuri V. Ramana
Summary: The article discusses the gold-catalysed intramolecular redox cyclization of o-alkynylnitrobenzens, highlighting its importance and potential for further research in metal catalysis. It also touches upon the idea of generating alpha-oxo gold carbenes via oxygen transfer to alkynes, establishing another significant aspect in gold catalysis.
Article
Chemistry, Organic
Pawan S. Dhote, Kishor A. Pund, Chepuri Ramana
Summary: The known nitrogen-transfer reagent 1,2-benzo[d]isoxazole has been used to trap the postulated α-oxo gold carbene intermediate involved in the [Au]-catalyzed internal redox process of 2-alkynylnitrobenzenes. This process led to the development of a general convergent method for the synthesis of highly functionalized quinazoline 1-oxides.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Applied
Pawan S. Dhote, Chepuri Ramana
Summary: In this study, the possibility of interrupting the gold-catalysed intramolecular cyclization was explored in order to develop simple tools for product diversification. It was found that using 1,2-benzisoxazoles, intermolecular nitrene transfer competed with intramolecular azidoalkyne cyclization resulting in spiro indol-3-ylidene derivatives. However, when anthranil was present, both intra- and intermolecular nitrene transfer processes led to the same product indol-3-ylidene.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Organic
Pawan S. Dhote, Chepuri Ramana
Summary: The hydrazine/phenylhydrazine-mediated reductive dicarbonyl coupling reactions have been successfully carried out under mild conditions, providing polycyclic aromatic compounds and azo-substituted polyaromatic compounds with a broad substrate scope and good functional group compatibility.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2022)
Article
Chemistry, Organic
Mahesh H. Shinde, Chepuri Ramana
Summary: A simple method for synthesizing pyridoindolone scaffolds with a spiroannulated tetrahydrofuran ring is described. The method involves intramolecular gold-catalyzed cycloisomerization and subsequent addition of indole C2 to the in situ generated oxocarbenium cation.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2022)
Article
Chemistry, Organic
Rupali G. Kalshetti, Swapnil V. Halnor, Chepuri V. Ramana
Summary: The Rh-catalyzed cross dehydrogenative coupling (CDC)/alkylation reaction was successfully carried out under ambient conditions, selectively on the pyrazole unit while directed by the pyridine. The scope of these reactions was demonstrated by using simple and conjugated olefins for CDC and various diazo esters and the TIPS-EBX reagent for alkylation. A small molecule library based on the bis-heterocyclic core of GBT440 was developed via C-H functionalization.
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Organic
Manoj N. Shet, Hemanth K. Nechooli, Chepuri V. Ramana
Summary: A simple method was developed for constructing the tetracyclic spiroketal skeleton of Lycibarbarine A and B. By coupling the fragments through epoxide opening with tetrahydroquinoline under solvent-free conditions, followed by oxidation and TBAF-mediated silyl deprotection spiroketalization, the complete tetracyclic core present in these natural products was established.
TETRAHEDRON LETTERS
(2023)
Article
Crystallography
Shaziyaparveen K. Siddiqui, C. V. Ramana, Rajesh G. Gonnade
Summary: The title compound crystallizes in monoclinic space group P2(1)/n with a planar geometry. The crystal structure is consolidated by C-H···O hydrogen bonding and a short C=O···CC (acetylene) contacts. Hirshfeld surface analysis indicates that H···H, C···H/H···C, and H···Br/Br···H interactions play a more important role in consolidating the crystal structure compared to H···O/O···H and C···C contacts.
ACTA CRYSTALLOGRAPHICA SECTION E-CRYSTALLOGRAPHIC COMMUNICATIONS
(2023)
Article
Chemistry, Organic
Swapnil V. V. Halnor, Pawan S. S. Dhote, Chepuri V. V. Ramana
Summary: A new catalytic method has been developed to construct the quinobenzoxazine core by employing gold-catalyzed cyclization of o-azidoacetylenic ketones in the presence of anthranils. The process involves a 6-endo-dig cyclization of o-azidoacetylenic ketone catalyzed by gold, leading to the formation of an alpha-imino gold carbene, which then transfers to anthranil to form the 3-aryl-imino-quinoline-4-one intermediate. This intermediate undergoes 6 pi-electrocyclization and aromatization to form the central quinobenzoxazine core. This transformation provides a new and scalable approach to diverse quinobenzoxazine structures under mild reaction conditions.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Mahesh H. Shinde, Chandrababu N. Kona, Chepuri Ramana
Summary: This study documents the gold catalysed alkynediol spiroketalization for assembling the central spiro-bis-THF fragments of symbiospirols A-C. The chiral pool approach using commercially available d-glucose and l-malic acid was employed to synthesize key building blocks. Additionally, two other possible diastereomers were synthesized to determine the relative stereochemistry of the unassigned THF-center of symbiospirols B/C.
NEW JOURNAL OF CHEMISTRY
(2022)
Review
Chemistry, Organic
Pawan S. Dhote, Pitambar Patel, Kumar Vanka, Chepuri V. Ramana
Summary: The pseudoindoxyl sub-structural motif is a unique subset of the oxygenated indole class of alkaloids, with interesting biological profiles. The challenges and future perspectives of synthesizing pseudoindoxyl compounds will be discussed based on recent developments.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2021)
Article
Chemistry, Organic
Sibadatta Senapati, Chepuri Ramana
Summary: A simple approach for synthesizing the C14-C28 fragment of eribulin has been developed by utilizing one-pot gold-catalyzed alkynol cyclization/Kishi reduction and cross-metathesis/Sharpless asymmetric dihydroxylation-cycloetherification reactions. The use of easily accessible building blocks and catalytic transformations highlights the efficiency of the method in constructing the THF/THP units for eribulin synthesis.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2021)
Article
Chemistry, Organic
Faiza Diaba, Gisela Trenchs
Summary: The first violet light-mediated synthesis of gamma- and delta-lactams from N-alkenyl trichloroacetamides is reported in this paper. The reactions are conducted in tetrahydrofuran or 2-methyltetrahydrofuran as the sole solvent without catalysts or additives, under non-anhydrous conditions in an air atmosphere where the solvent serves as the radical initiator.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2024)
Article
Chemistry, Organic
Feroze Hussain, Sajjad Ahmed, Ashiq Hussain Padder, Qazi Naveed Ahmed
Summary: This study reports a novel and efficient one-pot synthesis method for mixed phosphorotrithioates, which does not require supplementary additives and shows broad applicability.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2024)
Article
Chemistry, Organic
Hyunjin Oh, Ikyon Kim
Summary: A new 1,2,4-triazole-pyrrolo[1,2-a]pyrazine hybrid system, 6-acylpyrrolo[1,2-a][1,2,4]triazolo[5,1-c]pyrazine, was synthesized using a catalyst-free method. This method involved sequential exposure of pyrrole-2-carbonitrile-derived substrates to DMF-DMA and acyl hydrazide, resulting in the formation of acylated pyrazine and 1,2,4-triazole rings, enabling the installation of various substituents at specific positions on the core skeleton.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2024)
Article
Chemistry, Organic
Ming Yan, Si-fan Wang, Yong-po Zhang, Jin-zhong Zhao, Zhuo Tang, Guang-xun Li
Summary: Here we developed an efficient photocatalytic approach for the convenient preparation of sulfinamides. The reaction allows for the gram-scale preparation of sulfinamides and the one-pot synthesis of various sulfonyl amides.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2024)
Article
Chemistry, Organic
Farzaneh Bandehali-Naeini, Zahra Tanbakouchian, Noushin Farajinia-Lehi, Nicolas Mayer, Morteza Shiri, Martin Breugst
Summary: Two tandem catalytic systems were developed for the synthesis of novel 3,4-disubstituted maleimides using the same Ugi adducts. Different maleimide structures can be synthesized using either Pd or Cu catalysis.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2024)
Article
Chemistry, Organic
Tanya Raghava, Anjan Chattopadhyay, Subhadeep Banerjee, Nivedita Sarkar
Summary: Amine substitution of two ortho fluorine atoms of tetrafluoroterephthalonitrile through SNAr chemistry is easily achievable. But further fluorine substitution is only possible under forcing conditions, yielding valuable fluorophores for bioimaging.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2024)
Review
Chemistry, Organic
Anju Chadha, Santosh Kumar Padhi, Selvaraj Stella, Sowmyalakshmi Venkataraman, Thangavelu Saravanan
Summary: Alcohol dehydrogenases are enzymes that use cofactors for oxidation or reduction reactions of alcohols or carbonyl compounds. They are utilized in green chemistry and have applications in the production of pharmaceuticals. Recombinant enzymes have solved the challenge of producing purified enzymes in large quantities. Engineered alcohol dehydrogenases have been used in asymmetric synthesis in industry. Various methods have been established for regenerating expensive cofactors to make the enzymatic process more efficient and economically viable.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2024)
