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:
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
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.
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-
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.
Figure . Biologically active natural products.
We herein report a novel approach to hexahydropyrano[3,4-c]chromene derivatives by means of
Scheme . Preparation of the trans-fused hexahydropyrano[3,4-c]chromene derivatives
AnaloguesynthesisofcalyxinI and J:
(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
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-
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)
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)