01515nas a2200157   4500008004100000245006600041210006600107260000800173300001400181490000700195520098700202100002701189700002201216700001801238856010101256       2017                        eng d00aBronsted acid catalyzed enantioselective pericyclic reactions0 aBronsted acid catalyzed enantioselective pericyclic reactions  cJUL  a4023-40380 v733 aPericyclic reactions can be challenging processes to render asymmetric, due to the concerted and non polar nature of the transition states. Several examples have been reported in which a suitable catalyst binds to a heteroatom-containing substituent in the substrate and accelerates the reaction rate. The requirement of coordinating functionalized substrates has limited the generality of such asymmetric transformations. Multifunctional Bronsted acids are promising catalysts that represent a new paradigm in asymmetric pericyclic reactions. These chiral catalysts rely on multiple non-covalent interactions in the transition state for asymmetric induction, which has been utilized to activate more general substrate classes. In this review, we will cover recent advances in Bronsted acid catalyzed pericyclic reactions and discuss the impact of catalyst design on the expansion of substrate scope for highly enantioselective processes. (C) 2017 Elsevier Ltd. All rights reserved.1 aSleet, Christopher, E.1 aTambar, Uttam, K.1 aMaity, Pradip  uhttps://library.ncl.res.in/content/bronsted-acid-catalyzed-enantioselective-pericyclic-reactions01915nas a2200193   4500008004100000022001400041245010900055210006900164260000800233300001600241490000800257520123200265100001801497700002301515700002201538700001801560700001801578856012501596       2022                        eng d  a1520-610600aBlue fluorescence of cyano-tryptophan predicts local electrostatics and hydrogen bonding in biomolecules0 aBlue fluorescence of cyanotryptophan predicts local electrostati  cDEC  a10732-107400 v1263 a<p>
	Cyano-tryptophan is an unnatural fluorescent amino acid that emits in the visible region. Along with the structural similarity with tryptophan, the unique photophysical properties of this fluorophore make it an ideal probe for biophysical research. Herein, combining fluorescence spectroscopy, infrared spectroscopy, and molecular dynamics simulations, we show that the cyano-tryptophan's emission energy quantifies the underlying bond-specific noncovalent interactions in terms of the electric field. We further report the use of fluorophore's emission energy to predict its hydrogen bond characteristics. We demonstrate that combining experiments with molecular dynamics simulations can provide the hydrogen bonding status of the nitrile moiety. In addition, we report a method to differentiate between aqueous and nonaqueous hydrogen-bonding partners. Using a phenomenological approach, we demonstrate that the presence of the cyano-indole moiety is responsible for the distinct correlations between the fluorophore's emission and the electrostatic forces on the nitrile bond. As indole is a privileged scaffold for both native amino acids and nucleobases, cyano-indoles will have many multifaceted applications.</p>
1 aHaldar, Tapas1 aChatterjee, Srijan1 aAlam, Md, Nirshad1 aMaity, Pradip1 aBagchi, Sayan  uhttps://library.ncl.res.in/content/blue-fluorescence-cyano-tryptophan-predicts-local-electrostatics-and-hydrogen-bonding