Santhivardhana Reddy Yetra
@utsouthwestern.edu
Biochemistry Department
UTSouthwstern medical center
RESEARCH INTERESTS
Asymmetric catalysis Transitionmetal catalysis Photochemistry
Scopus Publications
Scopus Publications
Santhivardhana Reddy Yetra, Nathan Schmitt, and Uttam K. Tambar
Royal Society of Chemistry (RSC)
We have developed a chiral amine catalyzed enantioselective α-alkylation of aldehydes with amino acid derived pyridinium salts as alkylating reagents.
Francesco Ferlin, Santhivardhana Reddy Yetra, Svenja Warratz, Luigi Vaccaro, and Lutz Ackermann
Wiley
Dehydrogenative C-H arylations of 1,2,3-triazoles were accomplished with the aid of a reusable palladium catalyst in PEG. The widely applicable oxidative palladium-catalysis enabled the synthesis of fully decorated 1,2,3-triazoles with a broad functional group tolerance and ample substrate scope. The sustainability of the aerobic C-H arylation was reflected by the use of PEG as green reaction medium and demonstrated by recycling studies of the catalyst and the reaction medium.
Santhivardhana Reddy Yetra, Torben Rogge, Svenja Warratz, Julia Struwe, Wentao Peng, Philipp Vana, and Lutz Ackermann
Wiley
Chemoselective C-H arylations were accomplished through micellar catalysis by a versatile single-component ruthenium catalyst. The strategy provided expedient access to C-H-arylated ferrocenes with wide functional-group tolerance and ample scope through weak chelation assistance. The sustainability of the C-H arylation was demonstrated by outstanding atom-economy and recycling studies. Detailed computational studies provided support for a facile C-H activation through thioketone assistance.
Santigopal Mondal, Santhivardhana Reddy Yetra, Subrata Mukherjee, and Akkattu T. Biju
American Chemical Society (ACS)
This Account is aimed at highlighting the recent developments in the N-heterocyclic carbene (NHC)-catalyzed generation of α,β-unsaturated acylazolium intermediates and their subsequent reactivity with (bis)nucleophiles thereby shedding light on the power of this NHC-bound intermediate in organocatalysis. This key intermediate can be generated by the addition of NHCs to α,β-unsaturated aldehyde or acid derivatives. A wide variety of bisnucleophiles can add across the α,β-unsaturated acylazoliums to form various five and six-membered heterocycles and carbocycles. Moreover, suitably substituted nucleophiles can add to this intermediate and result in valuable products following cascade processes. Employing chiral NHCs in the process can result in the enantioselective synthesis of valuable compounds. In 2013, we developed a unified strategy for the enantioselective synthesis of dihydropyranones and dihydropyridinones by the NHC-catalyzed formal [3 + 3] annulation of 2-bromoenals with readily available 1,3-dicarbonyl compounds or primary vinylogous amides. This reaction takes place under mild conditions with low catalyst loading. Interestingly, employing enolizable aldehydes as the bisnucleophiles in this annulation afforded chiral 4,5-disubstituted dihydropyranones in spite of the competing benzoin/Stetter pathways. Moreover, the use of cyclic 1,3-dicarbonyl compounds such as 4-hydroxy coumarin/pyrazolone afforded the coumarin/pyrazole-fused dihydropyranones. In addition, a [3 + 2] annulation for the synthesis of spiro γ-butyrolactones was demonstrated using 3-hydroxy oxindoles as the bisnucleophile. The interception of α,β-unsaturated acylazolium intermediates with malonic ester derivatives having a γ-benzoyl group resulted in the enantioselective synthesis of functionalized cyclopentenes via a cascade process involving a Michael-intramolecular aldol-β-lactonization-decarboxylation sequence. The use of cyclic β-ketoamides as the coupling partner for catalytically generated α,β-unsaturated acylazoliums resulted in the enantioselective synthesis of spiro-glutarimide and the reaction proceeds in a Michael addition-intramolecular amidation pathway. We have recently demonstrated the enantioselective synthesis of tricyclic δ-lactones with three contiguous stereocenters by the reaction of enals with dinitrotoluene derivatives bearing electron-withdrawing groups, under oxidative conditions. This atom-economic cascade reaction proceeds in a Michael/Michael/lactonization sequence tolerating a range of functional groups. This technique was also used for the N-H functionalization of indoles for the enantioselective synthesis of pyrroloquinolines following the aza-Michael/Michael/lactonization sequence. The use of α-arylidene pyrazolinones as the bisnucleophiles for the tandem generation of dienolate/enolates combined with the NHC-catalyzed generation of α,β-unsaturated acylazoliums resulted in the enantioselective synthesis of pyrazolone-fused spirocyclohexadienones. This formal [3 + 3] annulation proceeds via the vinylogous Michael/spiroannulation/dehydrogenation sequence to afford spirocyclic compounds with an all-carbon quaternary stereocenter. It is reasonable to believe that the chemistry of α,β-unsaturated acylazoliums, catalytically generated through NHCs, will continue to flourish and will lead to amazing results. Future challenges in this area include the applications of this key intermediate in the synthesis of biologically active natural products and drugs.
Santhivardhana Reddy Yetra, Zhigao Shen, Hui Wang, and Lutz Ackermann
Beilstein Institut
Versatile C–H amidations of synthetically useful ferrocenes were accomplished by weakly-coordinating thiocarbonyl-assisted cobalt catalysis. Thus, carboxylates enabled ferrocene C–H nitrogenations with dioxazolones, featuring ample substrate scope and robust functional group tolerance. Mechanistic studies provided strong support for a facile organometallic C–H activation manifold.
N. Y. Phani Kumar, Torben Rogge, Santhivardhana Reddy Yetra, Alexander Bechtoldt, Eric Clot, and Lutz Ackermann
Wiley
Computational studies on decarboxylative C-H alkenylations provided key insights into the solvent-robust nature of C-H activation/decarboxylation domino reactions. These properties were exploited for ruthenium(II)-catalyzed C-H alkylations by a decarboxylative process with ample scope under copper-free and silver-free reaction conditions.
Santigopal Mondal, Subrata Mukherjee, Santhivardhana Reddy Yetra, Rajesh G. Gonnade, and Akkattu T. Biju
American Chemical Society (ACS)
Enantioselective synthesis of pyrazolone-fused spirocyclohexenols by the secondary amine-catalyzed cascade reaction of α,β-unsaturated aldehydes with α-arylidene pyrazolinones is reported. This formal [3 + 3] organocascade reaction proceeds through a vinylogous Michael-aldol sequence to furnish the spiroheterocycles with three stereocenters including an all-carbon quaternary center in good yields and selectivities. The catalytic generation of α,β-unsaturated iminium ions from enals and tandem dienolate/enolate formation from pyrazolinones are the key for the success of this spiroannulation reaction.
Subrata Mukherjee, Sumi Joseph, Anup Bhunia, Rajesh G. Gonnade, Santhivardhana Reddy Yetra, and Akkattu T. Biju
Royal Society of Chemistry (RSC)
The NHC-catalyzed enantioselective, oxidative formal [3 + 2] annulation of α,β-unsaturated aldehydes with 3-hydroxy oxindoles is presented.
Sethulekshmy Premaletha, Arghya Ghosh, Sumi Joseph, Santhivardhana Reddy Yetra, and Akkattu T. Biju
Royal Society of Chemistry (RSC)
NHC-catalyzed direct amidation of aldehydes with 2-aminobenzothiazoles allowed the synthesis of N-acyl 2-aminobenzothiazoles proceeding via acyl azolium intermediates.
Santhivardhana Reddy Yetra, Santigopal Mondal, Subrata Mukherjee, Rajesh G. Gonnade, and Akkattu T. Biju
Wiley
The enantioselective synthesis of pyrazolone-fused spirocyclohexadienones was demonstrated by the reaction of α,β-unsaturated aldehydes with α-arylidene pyrazolinones under oxidative N-heterocyclic carbene (NHC)catalysis. This atom-economic and formal [3+3] annulation reaction proceeds through a vinylogous Michael addition/spiroannulation/dehydrogenation cascade to afford spirocyclic compounds with an all-carbon quaternary stereocenter in moderate to good yields and excellent ee values. Key to the success of the reaction is the cooperative NHC-catalyzed generation of chiral α,β-unsaturated acyl azoliums from enals, and base-mediated tandem generation of dienolate/enolate intermediates from pyrazolinones.
Anup Bhunia, Santhivardhana Reddy Yetra, Rajesh G. Gonnade, and Akkattu T. Biju
Royal Society of Chemistry (RSC)
The K3PO4-mediated intramolecular Rauhut-Currier type reaction of chalcones having an enoate moiety leading to the formation of 4H-chromenes in moderate to good yields is demonstrated.
Atanu Patra, Anup Bhunia, Santhivardhana Reddy Yetra, Rajesh G. Gonnade, and Akkattu T. Biju
Royal Society of Chemistry (RSC)
NHC-catalyzed reaction of enals with N-substituted isatilidenes resulting in the diastereoselective synthesis of cyclopentanone-fused spirooxindoles proceeding via the homoenolate equivalent intermediates is reported.
Akkattu Biju, Santhivardhana Yetra, and Atanu Patra
Georg Thieme Verlag KG
Recent developments in the N-heterocyclic carbene (NHC)-catalyzed umpolung of aldehydes followed by their interception with activated carbon–carbon double bonds, namely the Stetter reaction, are presented. Advances in the inter- and intramolecular versions of this reaction, enantioselective transformations as well as the use of unactivated olefins in this type of reaction are discussed. 1 Introduction 2 Proposed Mechanism of the Stetter Reaction 3 Intramolecular Stetter Reactions 4 Intermolecular Stetter Reactions 5 Hydroacylation Reactions 6 Applications in Total Synthesis 7 Conclusion
Santhivardhana Reddy Yetra, Santigopal Mondal, Eringathodi Suresh, and Akkattu T. Biju
American Chemical Society (ACS)
The N-heterocyclic carbene (NHC)-organocatalyzed enantioselective annulation reaction of pyrazolones with α,β-unsaturated aldehydes proceeding via the chiral α,β-unsaturated acyl azolium intermediates under oxidative conditions is presented. The reaction afforded dihydropyranone-fused pyrazoles in moderate to good yields and good er values under operationally simple and base-free conditions.
Santigopal Mondal, Santhivardhana Reddy Yetra, Atanu Patra, Sunita S. Kunte, Rajesh G. Gonnade, and Akkattu T. Biju
Royal Society of Chemistry (RSC)
Highly enantioselective NHC-organocatalyzed synthesis of functionalized cyclopentenes by the reaction of modified enals with malonic ester derivatives having a γ-benzoyl group is reported.
Santhivardhana Reddy Yetra, Tony Roy, Anup Bhunia, Digvijay Porwal, and Akkattu T. Biju
American Chemical Society (ACS)
N-Heterocyclic carbene (NHC) catalyzed lactonization and lactamization of 2-bromoenals with heterocyclic C-H acids proceeding via the α,β-unsaturated acyl azolium intermediates is reported. The reaction furnished coumarin- or quinolinone-fused lactone/lactam derivatives. In addition, results of the enantioselective version of this reaction using chiral NHC are presented.
Santhivardhana Reddy Yetra, Trinadh Kaicharla, Sunita S. Kunte, Rajesh G. Gonnade, and Akkattu T. Biju
American Chemical Society (ACS)
N-Heterocyclic carbene (NHC)-catalyzed highly enantioselective lactonization of modified enals with enolizable aldehydes, proceeding via the α,β-unsaturated acylazolium intermediates, is reported. The reaction results in the asymmetric synthesis of synthetically important 4,5-disubstituted dihydropyranones.
Santhivardhana Reddy Yetra, Anup Bhunia, Atanu Patra, Manoj V. Mane, Kumar Vanka, and Akkattu T. Biju
Wiley
The N-heterocyclic carbene (NHC)-cata- lyzed generation of chiral a,b-unsaturated acylazoli- ums from 2-bromoenals followed by their intercep- tion with 1,3-dicarbonyl compounds or enamines, the formal (3+3) annulation reaction, is reported. The re- action results in the enantioselective synthesis of syn- thetically and medicinally important dihydropyran- A and dihydropyridinones, and tolerates a wide range of functional groups. It is noteworthy that the reaction takes place under mild reaction conditions utilizing relatively low catalyst loadings. In addition, based on DFT calculations, a mechanistic scenario involving the attack of the nucleophile from below the plane of the a,b-unsaturated acylazoliums, and the mode of enantioinduction is presented.
Trinadh Kaicharla, Santhivardhana Reddy Yetra, Tony Roy, and Akkattu T. Biju
Royal Society of Chemistry (RSC)
A facile, atom-economic and environmentally-benign protocol for the synthesis of biologically important oxindole derivatives in high yields has been demonstrated by employing isatins as carbonyl compound surrogates in a Passerini reaction carried out under solvent-free conditions. Moreover, electron-deficient phenols can also be used as the acid component in this reaction. In addition, the synthetic utility of the present methodology was examined by the one-pot synthesis of oxindoles with a free –OH group at the benzylic position.
Anup Bhunia, Santhivardhana Reddy Yetra, Sachin Suresh Bhojgude, and Akkattu T. Biju
American Chemical Society (ACS)
The N-heterocyclic carbene-catalyzed intermolecular Stetter reaction of aldehydes with α,β-unsaturated sulfones allows the atom-economic and selective formation of γ-keto sulfones in good yields. Key to the success of this unique transition-metal-free carbon-carbon bond-forming reaction is the right choice of the NHC precursor and base. The reaction tolerates a broad range of different aldehydes.
Anup Bhunia, Santhivardhana Reddy Yetra, and Akkattu T. Biju
Royal Society of Chemistry (RSC)
This tutorial review is aimed at highlighting recent developments in transition-metal-free carbon-carbon and carbon-heteroatom bond-forming reactions utilizing a versatile class of reactive intermediates, viz., arynes, which hold the potential for numerous applications in organic synthesis. Key to the success of the resurgence of interest in the rich chemistry of arynes is primarily the mild condition for their generation by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)aryl triflates. Consequently, arynes have been employed for the construction of multisubstituted arenes with structural diversity and complexity. The versatile transition-metal-free applications of arynes include cycloaddition reactions, insertion reactions and multicomponent reactions. In addition, arynes have found applications in natural product synthesis. Herein, we present a concise account of the major developments that occurred in this field during the past eight years.