@article {49053, title = {Base controlled rongalite-mediated reductive aldol/cyclization and dimerization of isatylidene malononitriles/cyanoacetates}, journal = {Organic and biomolecular chemistry}, volume = {22}, year = {2024}, month = {FEB}, pages = {1727-1732}, type = {Article}, abstract = {

In this study, we developed a novel methodology involving a base-controlled, rongalite-mediated reductive/aldol reaction, followed by cyclization of isatylidene malononitriles/cyanoacetates, resulting in the synthesis of spiro[2,3-dihydrofuran-3,3 {\textquoteleft}-oxindole]. Additionally, we have disclosed a rongalite-mediated dimerization process for isatylidene malononitriles, yielding dispiro[cyclopent-3 {\textquoteleft}-ene]bisoxindole. The utilization of rongalite in this reaction serves a dual purpose, acting both as a reducing agent and a C1 synthon. The developed approach has several advantages like a simple reaction setup, a wide substrate scope, requiring less time, using water as a green solvent, no metal or catalyst is required and products can be easily isolated via filtration with excellent yields under mild reaction conditions. A novel methodology was developed for the synthesis of spiro[2,3-dihydrofuran-3,3 {\textquoteleft}-oxindole] and dispiro[cyclopent-3 {\textquoteleft}-ene]bisoxindole under mild reaction conditions using inexpensive reagents.

}, issn = {1477-0520}, doi = {10.1039/d3ob01794j}, author = {Chaudhari, Suryakant S. and Nichinde, Chandrakant B. and Patil, Baliram R. and Girase, Amardipsing S. and Rama Krishna, Gamidi and Kinage, Anil K.} } @article {49505, title = {Efficient synthesis of 3,3'-Spirooxindole γ-Butyrolactone via Rongalite-mediated domino reductive aldol and spiro-lactonization reactions}, journal = {ChemistrySelect}, volume = {10}, year = {2025}, month = {FEB}, pages = {e202405996}, type = {Article}, abstract = {

In this study, we develop a novel methodology involving rongalite-mediated domino reductive/aldol reaction, followed by spiro-lactonization of 2-oxoindolin-3-ylidene acetates/malonates in presence of base to synthesis of 3,3 {\textquoteleft}-spirooxindole gamma-butyrolactone. The detail study, such as effect of solvent, effect of different base and substrate has been carried out. Scale up of this methodology is also done. Sodium hydroxymethanesulfinate dihydrate (rongalite) concurrently has a dual role in this context; it acts as a reducing agent as well as C1 synthon. This approach offers several advantages, such as being metal- and catalyst-free, involving a simple reaction protocol, having a wide substrate scope, using water as a green solvent, and providing good to excellent yields of the products under mild reaction conditions.

}, keywords = {(+/-) Coixspirolactam A \& [3, 3 {\textquoteleft}-spirooxindole gamma-butyrolactone], Domino reductive/aldol/spiro-lactonization, Good step economy, Rongalite as reductant \& C1 synthon, Water as a green solvent}, issn = {2365-6549}, doi = {10.1002/slct.202405996}, author = {Chaudhari, Suryakant S. and Nichinde, Chandrakant B. and Patil, Baliram R. and Girase, Amardipsing S. and Kinage, Anil K.} } @article {49536, title = {Sequential nitro-michael addition and reductive cyclization cascade reaction for diastereoselective synthesis of multifunctionalized 3,3'-pyrrolidinyl-spirooxindoles}, journal = {European Journal of Organic Chemistry}, volume = {28}, year = {2025}, month = {FEB}, type = {Article}, abstract = {

In this investigation, we elucidated, one-pot two stage efficient synthesis of multifuctionalized spiro[oxindole -3,3 {\textquoteleft}-pyrrolidine]. The methodology proceeds via organocatalyzed nitro-Michael addition reaction between indolylidenecyanoesters and nitroalkanes to formed nitro-Michael adduct which transformed into multifunctionalized 3,3 {\textquoteleft}-pyrrolidinyl-spirooxindoles by metal catalyzed reductive cyclization cascade. DFT investigations were conducted to elucidate the mechanism underlying the preferential reduction of the nitro group, with subsequent attack on the nitrile and ester groups remain inert throughout the reaction process. The approach is operationally simple, easily scalable, exhibits compatibility with readily accessible starting material and catalysts, thereby emphasizing cost-effectiveness.

}, keywords = {3 {\textquoteleft}-pyrrolidinyl spirooxindoles, DFT study for regioselective cyclization, Diastereoselective 3, organocatalysis, Pd/C catalysed partial reductive spirocyclization}, issn = {1434-193X}, doi = {10.1002/ejoc.202401121}, author = {Nichinde, Chandrakant B. and Bhati, Meema and Girase, Amardipsing S. and Patil, Baliram R. and Chaudhari, Suryakant S. and Gamidi, Rama Krishna and Joshi, Kavita and Kinage, Anil K.} }