@article { ISI:000262312300018, title = {First asymmetric total synthesis of penarolide sulfate A(1)}, journal = {European Journal of Organic Chemistry}, number = {36}, year = {2008}, month = {DEC}, pages = {6213-6224}, publisher = {WILEY-BLACKWELL}, type = {Article}, address = {COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA}, abstract = {

Penarolide sulfate A(1), with three contiguous stereogenic centers on a macrocyclic skeleton, affords promise as an alpha-glucosidase inhibitor. Herein, we describe the first asymmetric total synthesis of this natural product. A stereoselective strategy for rapid assembly of the complete framework of the 30-membered macrocyclic core is delineated herein. Sequential amidation and intramolecular Sonogashira cross-coupling reactions were pivotal to the success of our efforts. ((C) Wiley-VCH Verlag GmbH \& Co. KGaA, 69451 Weinheim, Germany, 2008)

}, keywords = {Asymmetric synthesis, C-C coupling, Dihydroxylation, epoxidation, Macrocycles, Regioselectivity, Total synthesis}, issn = {1434-193X}, doi = {10.1002/ejoc.200800680}, author = {Mohapatra, Debendra K. and Bhattasali, Debabrata and Gujar, Mukund K. and Khan, Mohammad Islam and Shashidhara, K. S.} } @article { ISI:000260587200010, title = {Self-diffusion coefficient of ring polymers in semidilute solution}, journal = {Journal of Polymer Science Part B-Polymer Physics}, volume = {46}, number = {21}, year = {2008}, month = {NOV}, pages = {2370-2379}, publisher = {WILEY-BLACKWELL}, address = {COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA}, abstract = {

In a topologically constraining environment the size of a flexible nonconcatenated ring polymer (macrocycles) and its dynamics are known to differ from that of linear polymers. Hence, the diffusion coefficient of ring polymers can be expected to be different from linear chains. We present here scaling arguments for the concentration and molecular weight dependence of self-diffusion coefficient of ring polymers in semidilute solutions, and show that contrary to expectations these scaling relations are identical to what is known for linear polymers. At higher concentrations excluded volume interactions arising from possibilities of segmental overlap can become effective for large ring polymers. In this regime the diffusion coefficient of large ring polymers shows a relatively weaker dependence on concentration and molecular weight. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2370-2379, 2008

}, keywords = {Diffusion, Macrocycles, Monte Carlo simulation}, issn = {0887-6266}, doi = {10.1002/polb.21569}, author = {Iyer, Balaj V. S. and Shanbhag, Sachin and Juvekar, Vinay A. and Lele, Ashish K.} } @article { ISI:000371239900016, title = {Enantioselective modular total synthesis of macrolides Sch725674 and C-4-epi-Sch725674}, journal = {European Journal of Organic Chemistry}, number = {6}, year = {2016}, month = {FEB}, pages = {1215-1226}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

The convergent total synthesis of Sch725674 has been accomplished by starting from (R)-1,2-epoxyheptane and assembling five modules in a highly stereoselective manner to give the final product in 6.6\% overall yield. The same strategy was extended to the synthesis of its C-4 epimer. Key reactions of the synthetic pathway include a Jacobsen hydrolytic kinetic resolution of an epoxide followed by its regioselective opening through a Yamaguchi-Hirao alkynylation, and ring-closing metathesis reaction to furnish the unique 14-membered ring macrolactone. In addition, the influence of protecting groups on the efficiency of the ring-closing metathesis (RCM) macrocyclization has been studied to maximize its yields.

}, keywords = {Asymmetric synthesis, Hydrolytic kinetic resolution, Macrocycles, Metathesis, Natural products}, issn = {1434-193X}, doi = {10.1002/ejoc.201501531}, author = {Sharma, Brijesh M. and Gontala, Arjun and Kumar, Pradeep} } @article {45713, title = {Engineering molecular topology: A pseudopeptidic macrocyclic figure-eight motif}, journal = {European Journal of Organic Chemistry}, year = {2017}, month = {FEB }, pages = {1120-1124}, type = {Article}, abstract = {

We herein present a rational-design strategy for the synthesis of molecules with figure-eight topology. The design concept is based on the incorporation of turn units in the back-bone of the macrocycle. The molecular structures and the folding are studied by X-ray crystallography and NMR, FT-IR, and CD spectroscopy.

}, keywords = {Macrocycles, noncovalent interactions, Pi interactions, topology, X-ray diffraction}, issn = {1434-193X}, doi = {10.1002/ejoc.201601365}, author = {Sharma, Sakshi and Thorat, Shridhar H. and Gonnade, Rajesh G. and Jasinski, Jerry P. and Butcher, Ray and Haridas, V.} } @article {43878, title = {Mixed-stack charge transfer crystals of pillar[5]quinone and tetrathiafulvalene exhibiting ferroelectric features}, journal = {Chemistry- A European Journal }, volume = {23}, year = {2017}, month = {SEP}, chapter = {12630-12635}, abstract = {

Ferroelectric materials find extensive applications in the fabrication of compact memory devices and ultra-sensitive multifunctional detectors. Face-to-face alternate stacking of electron donors and acceptors effectuate long-range unidirectional ordering of charge-transfer (CT) dipoles, promising tunable ferroelectricity. Herein we report a new TTF-quinone system-an emerald green CT complex consisting pillar[5]quinone (P5Q) and tetrathiafulvalene (TTF). The CT crystals, as determined by single crystal synchrotron X-ray diffraction, adopt a 1:1 mixed-stack arrangement of donor and acceptor with alternating dimers of TTF and 1,4-dioxane encapsulated P5Q. The TTF-P5Q.dioxane crystal possesses a macroscopic polarization axis giving rise to ferroelectricity at room temperature. The CT complex manifests ferroelectric features such as optical polarization rotation, temperature-dependent phase transition and piezoelectric response in single crystals. Ferroelectric behavior observed in P5Q-based CT complex widens the scope for further work on this structurally intriguing and readily accessible cyclic pentaquinone.

}, keywords = {Acceptor, Charge-transfer complexes, Chemistry, Conductors, DDQ, Donor, ferroelectric, Macrocycles, Organic Metals, Pi-interaction, Pillar[5]quinone, salts, Transfer Complexes, Transport}, issn = {0947-6539}, doi = {10.1002/chem.201702577}, author = {Shivakumar, Kilingaru I. and Swathi, Kadaba and Goudappagouda and Das, Tamal C. and Kumar, Ashwani and Makde, Ravindra D. and Vanka, Kumar and Narayan, Kavassery S. and Babu, Sukumaran Santhosh and Sanjayan, Gangadhar J.} } @article {44654, title = {First total synthesis of the proposed structure of pandangolide 1}, journal = {European Journal of Organic Chemistry}, year = {2018}, month = {JUL}, pages = {3352-3364}, abstract = {

The first total synthesis of the proposed structure of pandangolide 1 is reported. The synthesis was carried out using both an organocatalytic approach and a chiral-pool approach. The required stereochemistry at C-3 and C-5 was installed by using an organocatalytic aldol reaction and a stereoselective ketone reduction. The construction of the 12-membered core was achieved by 2-methyl-6-nitrobenzoic anhydride-mediated Shiina lactonization. The structure of target molecule was confirmed unambiguously by single-crystal X-ray analysis, but the optical rotation and NMR spectroscopic data of the synthetic pandangolide 1 were found to be inconsistent with the natural product.

}, keywords = {lactones, Macrocycles, Natural products, structure elucidation, synthesis design, Total synthesis}, issn = {1434-193X}, doi = {10.1002/ejoc.201800675}, author = {Show, Krishanu and Gonnade, Rajesh G. and Kumar, Pradeep} } @article {46324, title = {Access to a stereoisomer library of solomonamide macrocycles}, journal = {Chemistry-An Asian Journal}, year = {2019}, month = {OCT}, type = {Article; Early Access}, abstract = {

In an attempt towards understanding stereo-structure activity relationships (SSARs), we have prepared eight possible stereoisomers of solomonamide macrocycles, in particular, by changing the stereochemical pattern of non-peptide fragment AHMOA. Here, we have demonstrated different ways to construct three contiguous chiral centers present in solomonamide B macrocycle using substrate/reagent-controlled methods. These methods involve Brown crotylation, NHK reaction and Evans aldol addition as key steps to synthesize key non-peptide fragment. Further, these non-peptide fragments were converted to their corresponding macrocycles via ligand-free intramolecular Heck reaction.

}, keywords = {Crotylation, Heck reaction, Inflammation, Macrocycles, Stereochemistry}, issn = {1861-4728}, doi = {10.1002/asia.201901075}, author = {Jachak, Gorakhnath R. and Athawale, Paresh R. and Choudhury, Rahul and Kashinath, K. and Reddy, D. Srinivasa} } @article {48451, title = {Oligothiophene-ring-strapped perylene bisimides: functionalizable coaxial donor-acceptor macrocycles}, journal = {Angewandte Chemie-International Edition}, volume = {62}, year = {2023}, month = {JAN}, type = {Article}, abstract = {

Aesthetic designs from nature enable new knowledge to be gained and, at the same time, inspire scientific models. In this context, multicomponent macrocycles embody the advantage of precisely positioning the structural units to achieve efficient communication between them. However, the construction of a functionalizable macrocycle for ultrafast charge separation and stabilization has not been attempted. Herein, we report the synthesis, crystal structure, and transient absorption of a new functionalizable macrocycle consisting of an oligothiophene-ring-strapped perylene bisimide. Transient absorption results point to a sequential improvement in charge separation and stabilization from the macrocycle to the corresponding linear dimer and 2D polymer due to the unique design. Our macrocycle design with a supportive spatial arrangement of the donor and acceptor units will inspire the development of more complex synthetic systems with exciting electron-transfer and charge-separation features.

}, keywords = {Charge Separation, Donor-Acceptor Systems, Electron Transfer, Macrocycles, Perylene Bisimides}, issn = {1433-7851}, doi = {10.1002/anie.202212934}, author = {Dnyaneshwar Veer, Sairam and Chandrakant Wakchaure, Vivek and Asokan, Kiran and Dixit, Ruchi and Goswami, Tanmay and Saha, Ramchandra and Gonnade, Rajesh and Ghosh, Hirendra N. and Santhosh Babu, Sukumaran} }