Asymmetric catalytic arylation of ethyl glyoxylate using organoboron reagents and Rh(I)-phosphane and phosphane-phosphite catalysts

Herein we report the first application of Rh(I)-phosphane and phosphane-phosphite catalysts in the enantioselective catalytic arylation of ethyl glyoxylate with organoboron reagents, providing access to ethyl mandelate derivatives in high yield (up to 99%) and moderate to very good enantioselectivities (up to 75% ee). Commercial phosphane ligands, such as (R)-MonoPhos and (R)-Phanephos were tested, as well as non-commercial (R, R)-TADDOL-derived phosphane-phosphite ligands. Those ligands containing bulky substituents in the ortho-and para-positions of the chiral phosphite moiety were found to be the most selective

trans-Ethyl­enedi-p-phenyl­ene diacetate

The centrosymmetric title compound, C18H26O4, was prepared in high yield from 4-acetoxy­styrene via Ru-catalysed homo-olefin metathesis. Exclusive formation of the E-configurated isomer was observed. In the crystal, a strong C—H⋯π inter­molecular inter­action links the mol­ecules together

trans-1,2-Bis(3,5-dimethoxy­phen­yl)ethene

The title compound, C18H20O4, was prepared in high yield from 3,5-dimethoxy­styrene via a Ru-catalysed homo-olefin metathesis. Exclusive formation of the E-configurated isomer was observed. Inter­estingly, one symmetric unit contains two mol­ecules adopting an s-syn-anti and and an all-s-anti conformation

(RS)-Tricarbon­yl(η4-1,3-diacet­oxy-5,5-dimethyl­cyclo­hexa-1,3-diene)iron(0)

In the title compound, [Fe(C12H16O4)(CO)3], the diene moiety of the mol­ecule is virtually planar, with a C—C—C—C torsion angle of −1.4 (2)°. The six-membered ring exhibits a boat conformation, with torsion angles of 46.2 (2) and 46.5 (3)° for a double-bond and the two attached Csp 3 atoms. The Fe atom is coordinated to all four of the diene C atoms, with bond lengths between 2.041 (2) and 2.117 (2) Å. The Fe(CO)3 tripod adopts a conformation with one CO ligand eclipsing the Csp 3—Csp 3 single bond

Potassium (1-methoxy­carbonyl-2-methyl­prop-2-en-2-yl­idene)azinate

In the title compound, K+·C6H8NO4 −, the K+ cations have a coordination number of seven and are surrounded by four bidentate azinate anions. The methyl­ene groups of the anions are always directed towards the coordinated potassium cations. The N—C—C—C torsion angle is 101.2 (2)°. The orthogonal non-conjugated nature of the salt confirms the supposed geometry and reactivity of this compound

Synthetic α-Helical Peptides as Potential Inhibitors of the ACE2 SARS-CoV-2 Interaction

During viral cell entry, the spike protein of SARS-CoV-2 binds to the α1-helix motif of human angiotensin-converting enzyme 2 (ACE2). Thus, alpha-helical peptides mimicking this motif may serve as inhibitors of viral cell entry. For this purpose, we employed the rigidified diproline-derived module ProM-5 to induce α-helicity in short peptide sequences inspired by the ACE2 α1-helix. Starting with Ac-QAKTFLDKFNHEAEDLFYQ-NH2 as a relevant section of α1, a series of peptides, N-capped with either Ac-βHAsp-[ProM-5] or Ac-βHAsp-PP, were prepared and their α-helicities were investigated. While ProM-5 clearly showed a pronounced effect, an even increased degree of helicity (up to 63 %) was observed in sequences in which non-binding amino acids were replaced by alanine. The binding affinities of the peptides towards the spike protein, as determined by means of microscale thermophoresis (MST), revealed only a subtle influence of the α-helical content and, noteworthy, led to the identification of an Ac-βHAsp-PP-capped peptide displaying a very strong binding affinity (KD=62 nM)

Nucleophile- or light-induced synthesis of 3-substituted phthalides from 2-formylarylketones

The surprisingly facile conversion (isomerization) of 2-formyl-arylketones into 3-substituted phthalides, as observed for the marine natural product pestalone and its per-O-methylated derivative, was investigated using a series of simple 2-acylbenzaldehydes as substrates. The transformation generally proceeds smoothly in DMSO, either in a Cannizarro-Tishchenko-type reaction under nucleophile catalysis (NaCN) or under photochemical conditions (DMSO, 350 nm). © 2012 American Chemical Society.Fil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Cologne; AlemaniaFil: Augner, Daniel. University of Cologne; AlemaniaFil: Slavov, Nikolay. University of Cologne; AlemaniaFil: Schmalz, Hans Günther. University of Cologne; Alemani