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1,774 results on '"Tantillo, Dean J."'

201. Lessons in Strain and Stability: Enantioselective Synthesis of (+)-[5]-Ladderanoic Acid.

Author

Hancock, Erin N, Hancock, Erin N, Kuker, Erin L, Tantillo, Dean J, Brown, M Kevin, Hancock, Erin N, Hancock, Erin N, Kuker, Erin L, Tantillo, Dean J, and Brown, M Kevin

Abstract

The synthesis of structurally complex and highly strained natural products provides unique challenges and unexpected opportunities for the development of new reactions and strategies. Herein, the synthesis of (+)-[5]-ladderanoic acid is reported. En route to the target, unusual and unexpected strain release driven transformations were uncovered. This occurrence required a drastic revision of the synthetic design that ultimately led to the development of a novel stepwise cyclobutane assembly by an allylboration/Zweifel olefination sequence.

Published
2020

202. Exploiting the Potential of Meroterpenoid Cyclases to Expand the Chemical Space of Fungal Meroterpenoids.

Author

Mitsuhashi, Takaaki, Mitsuhashi, Takaaki, Barra, Lena, Powers, Zachary, Kojasoy, Volga, Cheng, Andrea, Yang, Feng, Taniguchi, Yoshimasa, Kikuchi, Takashi, Fujita, Makoto, Tantillo, Dean J, Porco, John A, Abe, Ikuro, Mitsuhashi, Takaaki, Mitsuhashi, Takaaki, Barra, Lena, Powers, Zachary, Kojasoy, Volga, Cheng, Andrea, Yang, Feng, Taniguchi, Yoshimasa, Kikuchi, Takashi, Fujita, Makoto, Tantillo, Dean J, Porco, John A, and Abe, Ikuro

Abstract

Fungal meroterpenoids are a diverse group of hybrid natural products with impressive structural complexity and high potential as drug candidates. In this work, we evaluate the promiscuity of the early structure diversity-generating step in fungal meroterpenoid biosynthetic pathways: the multibond-forming polyene cyclizations catalyzed by the yet poorly understood family of fungal meroterpenoid cyclases. In total, 12 unnatural meroterpenoids were accessed chemoenzymatically using synthetic substrates. Their complex structures were determined by 2D NMR studies as well as crystalline-sponge-based X-ray diffraction analyses. The results obtained revealed a high degree of enzyme promiscuity and experimental results which together with quantum chemical calculations provided a deeper insight into the catalytic activity of this new family of non-canonical, terpene cyclases. The knowledge obtained paves the way to design and engineer artificial pathways towards second generation meroterpenoids with valuable bioactivities based on combinatorial biosynthetic strategies.

Published
2020

203. Potential for Ladderane (Bio)synthesis from Oligo-Cyclopropane Precursors.

Author

Chen, Shu-Sen, Chen, Shu-Sen, Tantillo, Dean J, Chen, Shu-Sen, Chen, Shu-Sen, and Tantillo, Dean J

Abstract

Quantum chemical calculations were used to determine the energetic viability of several mechanisms for formation of ladderanes from oligocyclopropanes. Pathways involving radical cations, diradicals, and carbocations were considered, and a hybrid of carbocation and radical cation pathways was predicted to have the lowest overall barrier.

Published
2020

204. Development of potent inhibitors of the human microsomal epoxide hydrolase.

Author

Barnych, Bogdan, Barnych, Bogdan, Singh, Nalin, Negrel, Sophie, Zhang, Yue, Magis, Damien, Roux, Capucine, Hua, Xiude, Ding, Zhewen, Morisseau, Christophe, Tantillo, Dean J, Siegel, Justin B, Hammock, Bruce D, Barnych, Bogdan, Barnych, Bogdan, Singh, Nalin, Negrel, Sophie, Zhang, Yue, Magis, Damien, Roux, Capucine, Hua, Xiude, Ding, Zhewen, Morisseau, Christophe, Tantillo, Dean J, Siegel, Justin B, and Hammock, Bruce D

Abstract

Microsomal epoxide hydrolase (mEH) hydrolyzes a wide range of epoxide containing molecules. Although involved in the metabolism of xenobiotics, recent studies associate mEH with the onset and development of certain disease conditions. This phenomenon is partially attributed to the significant role mEH plays in hydrolyzing endogenous lipid mediators, suggesting more complex and extensive physiological functions. In order to obtain pharmacological tools to further study the biology and therapeutic potential of this enzyme target, we describe the development of highly potent 2-alkylthio acetamide inhibitors of the human mEH with IC50 values in the low nanomolar range. These are around 2 orders of magnitude more potent than previously obtained primary amine, amide and urea-based mEH inhibitors. Experimental assay results and rationalization of binding through docking calculations of inhibitors to a mEH homology model indicate that an amide connected to an alkyl side chain and a benzyl-thio function as key pharmacophore units.

Published
2020

205. Structure and Computational Basis for Backbone Rearrangement in Marine Oxasqualenoids

Author

Interreg, Ministerio de Ciencia e Innovación (España), Consejo Nacional de Ciencia y Tecnología (México), National Science Foundation (US), Fundación CajaCanarias, Cen-Pacheco, Francisco, Santiago-Benítez, Adrián J., Tsui, Ka Yi, Tantillo, Dean J., Fernández, José J., Hernández Daranas, Antonio, Interreg, Ministerio de Ciencia e Innovación (España), Consejo Nacional de Ciencia y Tecnología (México), National Science Foundation (US), Fundación CajaCanarias, Cen-Pacheco, Francisco, Santiago-Benítez, Adrián J., Tsui, Ka Yi, Tantillo, Dean J., Fernández, José J., and Hernández Daranas, Antonio

Abstract

Six novel oxasqualenoids (polyether triterpenes) were isolated from the red alga Laurencia viridis. Laurokanols A–E (1–5) comprise an unreported tricyclic core with a [6,6]-spiroketal system. Yucatecone (6) shows a biogenetically intriguing epimerization at C14. Quantum mechanical calculations were used to corroborate their structures and to explain key steps involved in the biogenetic mechanisms proposed for the formation of oxasqualenoids.

Published
2020

207. Hiscotropic rearrangements: Hybrids of electrocyclic and sigmatropic reactions

Author

Nouri, Dustin H. and Tantillo, Dean J.

Subjects
Cations -- Research, Cyclopropane compounds -- Research, Biological sciences, Chemistry
Abstract

An unusual reaction manifold for cyclopropylcarbinyl cations, uncovered using B3LYP and MP2 calculations, is described. The potential energies of these surfaces are often complicated, in some cases flat plateaus and bifurcations with turquoselectivity occurring in some cases due to favorable orbital interactions between the breaking C-C and C-H bonds.

Published
2006

208. Theoretical studies on farnesyl cation cyclization: Pathways to pentalenene

Author

Gutta, Pradeep and Tantillo, Dean J.

Subjects
Quantum chemistry -- Research, Ring formation (Chemistry) -- Research, Chemistry
Abstract

Studies are conducted using quantum chemical computations, on possible polycyclization pathways of the farnesyl cation leading to the complex sesquiterpene pentalenene. Direct deprotonation of intermediates on these pathways leads to sesquiterpene byproducts, such as humulene, protoludene and asterscadiene, supporting the idea that a key function of pentalenene synthase is to regulate the timing and location of proton removal.

Published
2006

209. Nonclassical carbocations as C-H hydrogen bond donors

Author

Bojin, Mihaela D. and Tantillo, Dean J.

Subjects
Carbon compounds -- Electric properties, Hydrogen -- Electric properties, Amines -- Electric properties, Chemical reactions -- Research, Chemicals, plastics and rubber industries
Abstract

Nonclassical cations are found to be competent C-H hydrogen bond donors. Interaction between nonclassical cations and amines are energetically favourable and their interaction energies are in the range of those for more traditional hydrogen bonds.

Published
2006

210. Multicenter bonding in carbocations with tetracoordibate protons

Author

Ponec, Robert, Bultinck, Patrick, Gutta, Pradeep, and Tantillo, Dean J.

Subjects
Protons -- Research, Carbon compounds -- Electric properties, Chemicals, plastics and rubber industries
Abstract

The nature of the bonding in a set of nonclassical carbocations with tetracoordinated protons inserted between two C=C pi bonds is investigated using the new computational methodology of generalized population analysis. The substitution of carbon by boron has reduced the strength of multicenter bonding revealing that the generalized population analysis is a useful tool for characterizing multicenter bonding in nonclassical structures.

Published
2006

216. The cationic cascade route to longifolene

Author

Ho, Gregory A., Nouri, Dustin H., and Tantillo, Dean J.

Subjects
Ring formation (Chemistry) -- Research, Olefins -- Atomic properties, Biological sciences, Chemistry
Abstract

The allyl-alkenyl-norbornenyl polycyclization, which is energetically viable, is used for forming the longifolene core. It is found out that the cation-alkene interaction is actually enhanced by the presence of the alkyl tether.

Published
2005

217. Remote substituent effects upon the rearrangements of housane cation radicals

Author

Gerken, James B., Wang, Selina C., Preciado, Alejandro B., Park, Young Sam, Little, R. Daniel, Nishiguchi, Gisele, and Tantillo, Dean J.

Subjects
Radicals (Chemistry) -- Research, Cations -- Research, Chemistry, Organic -- Research, Biological sciences, Chemistry
Abstract

The rearrangement of a series of housane-derived cation radicals is investigated. The results indicate that it is possible to influence the direction of migration in housane-derived cation radical rearrangements even when the regiochemical control unit is not directly appended to the migration terminus.

Published
2005

222. Fickle hexadienes. Manipulating the relative energies of chairlike and boatlike transition structures for the Cope rearrangement

Author

Tantillo, Dean J. and Hoffmann, Roald

Subjects
Chemistry, Organic -- Research, Alkadienes -- Physiological aspects, Olefins -- Physiological aspects, Cyclic compounds -- Physiological aspects, Isomerization -- Physiological aspects, Biological sciences, Chemistry
Abstract

Research has been conducted on the hexadienes with the chairlike and boatlike conformations. Results indicate that the pathways connecting chairlike and boatlike transition states allow for strained alkenes' isomerization pathways.

Published
2002

223. Complicated goings-on in the metal-manipulated ring-opening of cyclobutene

Author

Tantillo, Dean J. and Hoffmann, Roald

Subjects
Butane -- Chemical properties, Butane -- Structure, Iron compounds -- Chemical properties, Chemistry
Abstract

Transition metal-mediated pericyclic reactions is done involving an electrocyclic ring, opening step, and in this system, the pathway is predicted to dominate for more elaborate substrates. The possible alternative mechanisms for the parent Fe(CO)4-cyclobutene complex using hybrid HF-DFT calculations are examined.

Published
2001

224. Exploiting the Potential of Meroterpenoid Cyclases to Expand the Chemical Space of Fungal Meroterpenoids

Author

Mitsuhashi, Takaaki, primary, Barra, Lena, additional, Powers, Zachary, additional, Kojasoy, Volga, additional, Cheng, Andrea, additional, Yang, Feng, additional, Taniguchi, Yoshimasa, additional, Kikuchi, Takashi, additional, Fujita, Makoto, additional, Tantillo, Dean J., additional, Porco, John A., additional, and Abe, Ikuro, additional

Published
2020
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228. Development of potent inhibitors of the human microsomal epoxide hydrolase

Author

Barnych, Bogdan, primary, Singh, Nalin, additional, Negrel, Sophie, additional, Zhang, Yue, additional, Magis, Damien, additional, Roux, Capucine, additional, Hua, Xiude, additional, Ding, Zhewen, additional, Morisseau, Christophe, additional, Tantillo, Dean J., additional, Siegel, Justin B., additional, and Hammock, Bruce D., additional

Published
2020
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230. Development of Potent Inhibitors of the Human Microsomal Epoxide Hydrolase

Author

Singh, Nalin, primary, Barnych, Bogdan, additional, Negrel, Sophie, additional, Zhang, Yue, additional, Magis, Damien, additional, Roux, Capucine, additional, Hua, Xiude, additional, Ding, Zhewen, additional, Morisseau, Christophe, additional, Tantillo, Dean J., additional, Siegel, Justin, additional, and Hammock, Bruce D., additional

Published
2020
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245. Origins of regio-stereoselectivity in acid-promoted reactions of alpha-lactams

Author

Tantillo, Dean J. and Houk, K.N.

Subjects
Organic compounds -- Research, Microbial enzymes -- Research, Stereochemistry -- Research, Biological sciences, Chemistry
Abstract

Alpha-lactams or aziridinones and their varieties have been isolated by scientists and were characterized by a bulky substituent on nitrogen (N-tert-butyl, N-adamantyl, or N-trityl), which has been postulated to kinetically stabilize the alpha-lactam structure. Studies have revealed the involvement of cationic intermediates in reactions of weak nucleophiles with alpha-lactams. It has been predicted that the preferential attack of nucleophiles on the O-protonated intermediate will be the most likely pathway for nucleophile incorporation at C-3.

Published
1999

246. Bioinspired synthesis of pentacyclic onocerane triterpenoids† †Electronic supplementary information (ESI) available: Detailed experimental procedures, spectral data, DFT calculation, X-ray crystallographic data for 4 (CIF), 13 (CIF), 10 (CIF), 22 (CIF). CCDC 1529115–1529118. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc03903d

Author

Bartels, Florian, Hong, Young J., Ueda, Daijiro, Weber, Manuela, Sato, Tsutomu, Tantillo, Dean J., and Christmann, Mathias

Subjects
Chemistry
Abstract

The first chemical synthesis of pentacyclic onocerane triterpenoids (+)-cupacinoxepin and (+)-onoceranoxide is described., The first chemical synthesis of pentacyclic onocerane triterpenoids has been achieved. A putative biomimetic tricyclization cascade is employed to forge a fused decalin-/oxepane ring system. The synthetic route proceeds to (+)-cupacinoxepin in seven steps and to (+)-onoceranoxide in eight steps in the longest linear sequence, when starting from geranyl chloride and (+)-sclareolide. The bioinspired epoxypolyene cyclization is supported by computational and enzymatic studies.

Published
2017

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