Solid-state Spectroscopic and Structural Investigation of <Emphasis Type="Italic">cis</Emphasis>-(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>Au(<Emphasis Type="Italic">O</Emphasis>,<Emphasis Type="Italic">O</Emphasis>′-acac)

Abstract  The structure of cis-(CH₃)₂Au(O,O′-acac) was investigated by single-crystal X-ray diffraction. It crystallizes in the orthorhombic space group Cmca with unit cell dimensions a = 6.7831(13) ?, b = 15.080(3) ?, c = 18.073(3) ? and α = β = γ = 90°. The molecule is planar but lacks a C₂ axis in the solid-state, with two Au–C bond lengths that differ by 0.078(21) ? due to crystal packing effects. The inequivalence of the crystallographic carbon positions is evident in the solid-state ¹³C CP-MAS NMR spectrum, which was recorded at low temperature due to the thermal sensitivity of the compound during magic-angle spinning. Head-to-tail stacking, which creates short intermolecular paths, was reproduced computationally in a dimer model. Graphical Abstract   Solid-state Spectroscopic and Structural Investigation of cis -(CH ₃ ) _Au 2 ( O , O ′-acac) Miyako Hisamoto • Swarup Chattopadhyay • Juergen Eckert • Guang Wu • Susannah L. Scott In the solid state, cis-(CH₃)₂Au(O,O′-acac) has no C₂ axis, two different Au–C bond lengths (1.960, 2.038 ?; Δd = 0.078(21) ?) and a close Au–C…C–Au contact; these features give rise to additional features in the ¹³C CP-MAS NMR spectrum.     

Data Structures for Extension Violations in a Query Range

Design Rule Checking (DRC) in VLSI design involves checking if a given VLSI layout satisfies a given set of rules and reporting the violations if any. We propose data structures for reporting violations of the minimum extension rule in a query window of interest.     

Enhancement of synchronized chaotic state in a delay-coupled complex neuronal network

Nonlinear Dynamics - Synchronized firing of neurons is considered as one of the crucial characteristics for signal transmission and neuronal coding. In this article, spatiotemporal synchronization...     

Unicyclic graphs with bicyclic inverses

A graph is nonsingular if its adjacency matrix A(G) is nonsingular. The inverse of a nonsingular graph G is a graph whose adjacency matrix is similar to A(G)^?1 via a particular type of similarity. Let H denote the class of connected bipartite graphs with unique perfect matchings. Tifenbach and Kirkland (2009) characterized the unicyclic graphs in H which possess unicyclic inverses. We present a characterization of unicyclic graphs in H which possess bicyclic inverses.     

Protecting group directed cyclization: asymmetric synthesis of both cis- and trans-dihydrexidine from a common precursor

Protection group of amino- and tethered o-arene functionality of 1,4-aryl-2-amino-1-butanol derived from l-serine dictates the cyclization mode under acidic conditions leading to reverse diastereoselectivity. N-Boc and acetal protected amino alcohol undergo cascade cyclization providing exclusively cis-dihydrexidine via reduction, where formation of C-ring (isoquinoline unit) prior to Friedel–Crafts cyclization control the cis-stereochemistry of the B-ring. N-Cbz and O-benzyl protection direct first F–C cyclization yielding the trans-1-aryl-2-aminotetralin and subsequent deprotection-cyclization forming the C-ring afforded dihydrexidine.     

Enantioselective Desymmetrization of Prochiral Cyclohexanones by Organocatalytic Intramolecular Michael Additions to α,β‐Unsaturated Esters

A new catalytic asymmetric desymmetrization reaction for the synthesis of enantioenriched derivatives of 2‐azabicyclo[3.3.1]nonane, a key motif common to many alkaloids, has been developed. Employing a cyclohexanediamine‐derived primary amine organocatalyst, a range of prochiral cyclohexanone derivatives possessing an α,β‐unsaturated ester moiety linked to the 4‐position afforded the bicyclic products, which possess three stereogenic centers, as single diastereoisomers in high enantioselectivity (83–99 % ee) and in good yields (60–90 %). Calculations revealed that stepwise C? C bond formation and proton transfer via a chair‐shaped transition state dictate the exclusive endo selectivity and enabled the development of a highly enantioselective primary amine catalyst.     

Asymmetric synthesis of a dopamine D1 agonist,dihydrexidine from d-serine

A scalable asymmetric synthesis of trans-2-amino-6,7-dimethoxy-1-phenyltetralin 2 and its N-nosyl derivative 12 have been achieved from Garner aldehyde derived from easily available d-serine using a stereoselective PhMgBr addition, Wittig reaction and TFA-mediated Friedel–Crafts cyclization as the key steps. The synthesis of dihydrexidine is accomplished from the N-nosyl-2-amino-1-phenyltetralin 12.