358 research outputs found
Gold(I)-Catalyzed Cascade Cyclization of Anilines with Diynes: Controllable Formation of Eight-Membered Ring-Fused Indoles and Propellane-Type Indolines
Heterocycle-fused indoles or indolines are distributed widely in a variety of natural products, bioactive agents, and pharmaceuticals. Herein, we describe the development of gold-catalyzed cascade reactions of anilines with diynes to form eight-membered ring-fused indoles and propellane-type indolines, both of which proceed through an intramolecular 5-endo-dig hydroamination followed by an 8-endo-dig cycloisomerization. Controllable formation of eight-membered ring-fused indoles and propellane-type indolines was achieved through selection of the ligands and/or solvents. Protic solvents such as alcohols or IPr ligand favored the formation of eight-membered ring-fused indoles, whereas the use of Buchwald’s type ligands and/or nonpolar solvents gave propellane-type indoline predominantly. This reaction provides rapid access to two types of fused nitrogen heterocycles from simple aniline derivatives
Chiral symmetry restoration, eigenvalue density of Dirac operator and axial U(1) anomaly at finite temperature
We reconsider constraints on the eigenvalue density of the Dirac operator in
the chiral symmetric phase of 2 flavor QCD at finite temperature. To avoid
possible ultra-violet(UV) divergences, we work on a lattice, employing the
overlap Dirac operator, which ensures the exact "chiral" symmetry at finite
lattice spacings. Studying multi-point correlation functions in various
channels and taking their thermodynamical limit (and then taking the chiral
limit), we obtain stronger constraints than those found in the previous
studies: both the eigenvalue density at the origin and its first and second
derivatives vanish in the chiral limit of 2 flavor QCD. In addition we show
that the axial U(1) anomaly becomes invisible in susceptibilities of scalar and
pseudo scalar mesons, suggesting that the 2nd order chiral phase transition
with the O(4) scaling is not realized in 2 flavor QCD. Possible lattice
artifacts when non-chiral lattice Dirac operator is employed are briefly
discussed.Comment: 39 pages, 1 figure(2 eps files), a version published in PR
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