Nandita Biswas

Bio: Nandita Biswas is an academic researcher from Indian Institute of Technology Guwahati. The author has contributed to research in topics: Borrowing hydrogen & Ruthenium. The author has an hindex of 2, co-authored 4 publications receiving 30 citations.

Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source.

Abstract: Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp3)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.

Acceptorless dehydrogenative construction of C[double bond, length as m-dash]N and C[double bond, length as m-dash]C bonds through catalytic aza-Wittig and Wittig reactions in the presence of an air-stable ruthenium pincer complex.

Abstract: The construction of C[double bond, length as m-dash]N bonds was achieved by the dehydrogenative coupling of alcohol and azide via aza-Wittig type reaction. The reaction is catalyzed by an acridine-derived ruthenium pincer complex and does not use any oxidant. The present protocol offers a wide substrate scope, including aliphatic, aryl or heteroaryl alcohol/azides. This expeditious protocol was successfully applied to construct a C[double bond, length as m-dash]C bond directly from alcohol via dehydrogenative Wittig reaction. Furthermore, the synthesis of structurally important pyrrolo[1,4]benzodiazepine derivatives was also achieved by this methodology.

Synthesis of 1,8-Dioxo-decahydroacridine Derivatives via Ru-Catalyzed Acceptorless Dehydrogenative Multicomponent Reaction.

Abstract: A Ru-catalyzed acceptorless dehydrogenative multicomponent reaction has been developed. This reaction offers a cost-effective and simple operational strategy to synthesize biologically active 1,8-dioxodecahydroacridine derivatives. The protocol provides a wide range of substrate scope and various functional groups are also well tolerated under the reaction condition. To shed light on the mechanistic and kinetic study, some controlled experiments and deuterium labeling experiments were executed. A time-dependent product distribution experiment is also presented and the reaction scale-up is performed to highlight the practical utility of this strategy.

Tandem transformations and multicomponent reactions utilizing alcohols following dehydrogenation strategy

Abstract: The construction of new C-C, C-N and C-O bonds by replacing hazardous and waste generating chemicals with alcohols as the greener and sustainable reagents is one of the emerging areas of research. In consequence, the borrowing hydrogen and acceptorless dehydrogenative coupling principles have received significant momentum to synthesize various alkylated molecules and N-heterocycles. In the tandem transformations and multi-component reactions, simple substrates are directly converted to new functionalities or complex molecular systems using a single reaction set-up. In this review, the progress of tandem transformation of nitro, nitrile and azide functionalities as well as multi-component reactions utilizing alcohols is summarised. These transformations lead to the atom-economical synthesis of a wide range of alkylated imines, amines, amides and N-heterocycles such as pyrrole, pyridine, pyrimidine, quinoxaline, etc.

Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source.

Abstract: Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp3)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.

Recent advances in sustainable organic transformations using methanol: expanding the scope of hydrogen-borrowing catalysis

Abstract: The present review focuses on recent progress achieved from 2017 to March 2021 using methanol as a C1-alkylating agent. A series of novel metal-catalyzed hydrogen-borrowing processes has been developed using methanol. Most importantly, the non-precious-metal-catalyzed activation and functionalization of methanol are discussed in detail, including mechanistic investigations. The design of interesting pincer complexes for the conceptual activation of methanol, which holds great potential, is covered. Furthermore, the methylation of nitroarenes or alkanes and the upgrading of methanol to higher-order alcohols, including Guerbet-type transformations and β-alkylations using molecularly defined catalysts, are discussed. Recently reported C, N, and O methylations will be covered, including ketone alkylations (α or β), N-formylations, amidations, and sulfonylations, as well as other interesting areas. The exciting applications of industrially important heterogeneous catalysts and their application in methanol activation are covered. The synthesis of various important drugs having a “–CH3” motif and late-stage methylation, including the incorporation of the medicinally useful “–CD3” motif, are interesting additions to the present discussions. Photo- and electro-catalytic transformations using methanol will also be discussed. The limited number of review articles covering this subject area has limited its understanding; therefore, we believe that this updated review article is necessary to focus the attention of researchers in this direction.