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Research Summary


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Research Summary

  1. 1. RESEARCH SUMMARY 1. Cu(OTf)2-catalyzed synthesis of 2,3-disubstituted indoles and 2,4,5- trisubstituted pyrroles from α-diazoketones B. V. Subba Reddy,* M. Ramana Reddy, Y. Gopal Rao, J. S. Yadav and B. Sridhar A novel method has been devised for the synthesis of 2,4,5-trisubstituted pyrrole derivatives through the coupling of α-diazoketones with β-enaminoketones and esters using 10 mol % of Cu(OTf)2. A wide range of 2,3-disubstituted indole derivatives were also prepared from α- diazoketones and 2-aminoaryl or alkyl ketones. Finally, we attempted the synthesis of homofascaplysin C through the coupling of alkyl diazoketone with 2-aminoacetophenone. The pentacyclic pyrido[1,2-a:3,4-b]-diindole core is found in various natural products such as fascaplysin and homofascaplysin C which were isolated from Fascaplysinopsis Bergquist sp. and Fijian sponge F. reticulata, respectively. Application in the short synthesis of natural alkaloid Homofascaplysin C: Homofascaplysin C:
  2. 2. Construction of Indole core moiety via our methodology and Fisher-indole synthesis were key steps involved in the synthesis of Homofascaplysin C. (Org. Lett., 2013, 15, 464-467) 2. Acetal initiated Prins bicyclization for the synthesis of furo[3,4-c]furan lignans and pyrano[3,4-c]pyran derivatives B. V. Subba Reddy,* M. Ramana Reddy, B. Sridhar and S. Kiran Kumar Since the biological activities of lignans have been reported, natural furofurans have become synthetic targets for many groups. the two main challenges in the synthesis of furofurans are the control of the stereochemistry at the ring junction and the configuration of the aryl substituents. The aim of this project was to develop simple methodology which generated selectively all the combinations of stereocentres, allowing access to the lignans. Figure. Natural furo[3,4-c]furan lignans methodology development for construction of bicyclic furans: The first synthesis of furofuran analogues have been achieved in single step involving cascade prinscyclization, followed by traping of oxonium ion by hydroxy group.
  3. 3. The principal aim is to synthesise the natural furofuran analogues. we herein developed an acetal initiated Prins cascade reaction for the synthesis of cis-fused hexahydrofuro[3,4-c]furan derivatives. It also provides a direct access to produce a new series of pyrano[3,4-c]pyran derivatives in a single-step process. Scheme . Prins bicyclisation stratagy for synthesis of furo[3,4-c]furan lignans and pyrano[3,4- c]pyran derivatives we applied this protocol to generate allocolchicine analogues. The allocolchicine (A) and N- acetyl colchinol-O-methyl ether (NCME) (B) are seven- membered biaryl derivatives of naturally occurring colchicines, which are potent tubulin inhibitors. (Org. Biomol. Chem. 2014, 12, 4754-4762) 3. Tandem Prins cyclization for the stereoselective synthesis of 4,5-diaryl- hexahydropyrano[3,4-c]chromene skeleton of calyxins I & J. B. V. Subba Reddy,* M. Ramana Reddy, S. Gopal Reddy, B. Sridhar and S. Kiran Kumar Diarylheptanoids were isolated from Alpinia blepharocalyx seeds and are used in the Chinese traditional medicine for the treatment of stomach disorders. 3 The calyxins are a family of diarylheptanoids , they are known to display a broad spectrum of biological activities such as antioxidant, antiinflammatory, antihepatotoxic, anticancer and antiulcer. The principal aim is to synthesise the natural calyxin I & J analogues. we herein developed Prins cascade reaction for the synthesis of calyxin I & J derivatives.
  4. 4. Figure . Biologically active natural products. We herein report a novel approach to hexahydropyrano[3,4-c]chromene derivatives by means of Prins cyclization. Scheme . Preparation of the trans-fused hexahydropyrano[3,4-c]chromene derivatives AnaloguesynthesisofcalyxinI and J:
  5. 5. (Eur. J. org. chem, 2015, Article in Press) DOI: 10.1002/ejoc.201500117. 4. Tandem Prins/Pinacol reaction for the synthesis of oxaspiro[4.5]decan-1-one scaffolds B . V. Subba Reddy,* S. Gopal Reddy, M. Ramana Reddy, Manika Pal Badhra and A. V. S. Sarma A novel BF3.OEt2 catalyzed Pinacol-Terminated Prins Cyclization strategy has been developed for the synthesis of 7,9--substituted-8-oxaspiro[4.5]decan-1-ones in good yields with excellent selectivity. This is the first example of the synthesis of 8-oxaspiro[4.5]decan-1-ones from 1-(4- hydroxybut-1-en-2-yl)cyclobutanol. This straight forward procedure was also applicable to a wide range of aldehydes, such as α,β- unsaturated aldehydes, aromatic aldehydes, and aliphatic aldehydes. Scheme: Synthesis of 7,9- di substituted-8-oxaspiro[4.5]decan-1-one scaffolds (Org. Biomol. Chem. 2014, 12, 7257-7260)
  6. 6. 5. Intramolecular C-O/C-S bond insertion of α-diazoesters for the synthesis of 2-aryl- 4Hbenzo[d][1,3]oxazine and 2-aryl-4H-benzo[d][1,3]thiazine derivatives B. V. Subba Reddy,* R. Anji babu, M. Ramana Reddy, Jagan Mohan Reddy and B. Sridhar. A novel method has been devised for the synthesis of substituted benzo[d][1,3]oxazine-4- carboxylate derivatives through the intramolecular diazo insertion using 10 mol % of Cu(OTf)2. Starting material preparation: synthesis of benzo[d][1,3]oxazine and thiazine 4-carboxylate derivatives (RSC Adv., 2014, 4, 44629-44633) Thank you