Nitin S. Dange

Sequential Organocatalytic Stetter and Michael-Aldol Condensation Reaction: Asymmetric Synthesis of Fully Substituted Cyclopentenes via a [1 + 2 + 2] Annulation Strategy

A stereoselective synthesis of fully substituted cyclopentenes has been achieved by a sequential organocatalyzed Stetter and Michael-aldol condensation of aromatic aldehydes, nitroalkenes, and α,β-unsaturated aldehydes via the [1 + 2 + 2] annulation strategy with excellent diastereoselectivities and enantioselectivities (up to >99% ee).

Dynamic Kinetic Asymmetric Synthesis of Five Contiguous Stereogenic Centers by Sequential Organocatalytic Stetter and Michael−Aldol Reaction: Enantioselective Synthesis of Fully Substituted Cyclopentanols Bearing a Quaternary Stereocenter

A synthesis of fully substituted cyclopentanes bearing a quaternary carbon center and five contiguous stereogenic centers has been achieved by sequential organocatalyzed Stetter and Michael-Aldol reactions of heteroaromatic aldehydes, nitroalkenes, and α,β-unsaturated aldehydes via the [1 + 2 + 2] annulation strategy with dynamic kinetic asymmetric transformation and excellent enantioselectivities (up to >99% ee).

One-Pot Organocatalytic Enantioselective Domino Double-Michael Reaction and Pictet-Spengler–Lactamization Reaction. A Facile Entry to the “Inside Yohimbane” System with Five Contiguous Stereogenic Centers

An expedited method was developed for the enantioselective synthesis of dodecahydrobenz[a]indolo[3,2-h]quinolizine containing five contiguous stereogenic centers with high enantioselectivities (>99% ee). The methodology comprises a domino organocatalytic double Michael reaction and Pictet-Spengler-lactamization reaction. The structures and absolute configurations of the appropriate products were confirmed by X-ray analysis.

Organocatalytic Michael-Knoevenagel-hetero-Diels-Alder reactions: an efficient asymmetric one-pot strategy to isochromene pyrimidinedione derivatives.

Synthesis of isochromene pyrimidinedione derivatives having five stereocenters has been achieved by a one-pot Michael-Knoevenagel condensation-inverse-electron-demand hetero-Diels-Alder reaction of α, β-unsaturated aldehydes, olefinic nitroalkanes, and 1,3-dimethylbarbituric acid via a one-pot strategy with excellent diastereo- and enantioselectivities (up to 99% ee). The structures and absolute configurations of the products were confirmed by X-ray analysis.

One-Pot Asymmetric Synthesis of Seven-Membered Carbocycles Cyclohepta[b]indoles via a Sequential Organocatalytic Michael/Double Friedel–Crafts Alkylation Reaction

A new method has been developed for the enantioselective synthesis of highly functionalized cyclohepta[b]indoles with high enantioselectivity (up to 96% ee). The process combines an enantioselective organocatalytic Michael addition and a highly efficient double Friedel-Crafts reaction sequence in one pot with good yields and stereoselectivity. The structures and absolute configurations of the products were confirmed by X-ray analysis.

Organocatalytic asymmetric anti-selective Michael reactions of aldehydes and the sequential reduction/lactonization/Pauson-Khand reaction for the enantioselective synthesis of highly functionalized hydropentalenes.

A new method has been developed for the enantioselective synthesis of highly functionalized hydropentalenes bearing up to four stereogenic centers with high stereoselectivity (up to 99% ee). This process combines an enantioselective organocatalytic anti-selective Michael addition with a highly efficient one-pot reduction/lactonization/Pauson-Khand reaction sequence. The structures and absolute configurations of the products were confirmed by X-ray analysis.

One-pot biomimetic total synthesis of yuehchukene via the organocatalytic alkylation–cyclization process of a sterically encumbered α-alkyl enal

A concise synthesis of yuehchukene has been achieved using organocatalytic Friedel–Crafts alkylation of indole to a sterically encumbered α-alkyl enal as the key step. A racemization process during the subsequent cyclization steps of the conjugate adduct to yuehchukene was observed.

Functionalization of Silyldienol Ethers at the γ-Position via 2-Silyloxypentadienyl Cations

This report describes Brønsted acid catalyzed de novo synthesis of silyldienol ethers bearing tetrasubstituted double bonds via an intermediacy of 2-silyloxypentadienyl cations. The reactivity of these novel cationic intermediates could be modulated and harnessed toward direct nucleophilic additions regioselectively at the γ-position to produce highly functionalized silyldienol ethers with tunable control of the resulting double bond geometry.

Regioselective Functionalization of Enamides at the α-Carbon via Unsymmetrical 2-Amidoallyl Cations

A new method to functionalize enamides via an intermediacy of unsymmetrical 2-amidoallyl cations is reported. Generated under mild Brønsted acid catalysis, these reactive species were found to undergo addition with various nucleophiles at the less substituted α-carbon to produce highly substituted enamides in high yields with complete control of regioselectivity.

Visible-Light-Mediated Addition of Phenacyl Bromides onto Cyclopropenes

Visible-light-promoted addition of α-bromoacetophenones onto the cyclopropene π-system in the presence of the fac-Ir(ppy)3 catalyst was shown to afford the corresponding 1(4H)-naphthalenones. The syn-carboarylation of the cyclopropene is followed by a cyclopropane ring opening under the basic conditions, allowing the formation of two C-C bonds and the generation of 1(4H)-naphthalenones bearing an all-carbon benzylic quaternary stereocenter.