The first intermolecular Friedel-Crafts acylation with beta-lactams

The first intermolecular Friedel-Crafts acylation of a variety of aromatic substrates with azetidinones is described. The Friedel-Crafts acylations are performed under very mild conditions, using trifluoromethanesulfonic acid to produce beta-amino aromatic ketones in excellent yields.     

Total synthesis of the natural product (±)-dibromophakellin and analogues

(±)-Dibromophakellin has been synthesized in two steps from a known alkene intermediate. The key step in the synthesis is the NBS olefin activation to facilitate the addition of a guanidine molecule across the double bond.     

Über den Grad der Approximation mit Bernstein-Polynomen

Ohne Zusammenfassung     

Sensitization of cancer cells to DNA damaging agents by imidazolines

Apoptosis, or programmed cell death, is a cellular mechanism used to regulate cell number and eliminate damaged or mutated cells. Concomitant with the initiation of the apoptotic cell signal, chemotherapeutic agents also induce anti-apoptotic factors, such as NF-kappaB, which compromise the overall efficacy of chemotherapeutic anticancer treatment. Here we describe an adjuvant therapy in which a small molecule is used to sensitize cancer cells toward apoptosis induced by chemotherapeutics. Our results indicate that the imidazoline 1d modulates the pro-survival NF-kappaB pathway and selectively sensitizes cancer cells toward DNA damaging agents, thus enhancing the overall efficacy of the treatment. Pretreatment of cancer cells with the noncytotoxic imidazoline 1d (10 nM) resulted in a significant increase in apoptosis and anticancer efficacy of the clinically significant DNA damaging agents camptothecin and cisplatin. Noncancerous cells remained unaffected during this regimen.     

One-pot Friedel-Crafts/Robinson-Gabriel synthesis of oxazoles using oxazolone templates

[reaction: see text] We report herein a one-pot synthesis of 2,4,5-trisubstituted oxazoles via a Friedel-Crafts/Robinson-Gabriel synthesis using a general oxazolone template. Treatment of the oxazolone template with a range of aromatic nucleophiles provided the highly substituted oxazoles in good yields.     

Multiple quantum well structures and high-power lasers of gaas- algaas grown by metalorganic vapor phase epitaxy (MOVPE)1

GaAs/AlGaAs GRIN-SCH type multiple quantum well lasers with four wells of 11 nm GaAs, grown in an MOVPE chimney reactor, exhibit an output power as high as 110 mW/facet (CW, 30°C; 5 μm stripe) and 1.3 W/facet (pulsed, 30°C; 53 μm stripe) until catastrophic optical damage occurs. 2000 hours life tests conducted at 60°C and 15 mW CW show no noticeable degradation for the 5 μm stripe laser with a reflective coating on both facets. Raman spectroscopy on similar multiple quantum well structures with 65 GaAs wells is used to ascertain that the wells have minimum residual aluminum- content.     

The diverse chemistry of oxazol-5-(4H)-ones

The assembly of structurally diverse scaffolds via substrate controlled diversity oriented synthesis (DOS) has proven to be an effective tool in the discovery of novel biologically important compounds. This tutorial review aims to summarize some of the more recent applications of oxazolones as a general template for the stereoselective syntheses of amino acids and heterocyclic scaffolds. A brief introduction covers a short history, nomenclature and general reactivity of oxazolones. The main body of this tutorial review highlights several applications of oxazolones as starting blocks for the diverse and stereoselective synthesis of amino acids, oxazoles, beta-lactams, pyrroles, imidazolines, pyrrolines, and imidazoles.     

Indolo‐Phakellins as β5‐Specific Noncovalent Proteasome Inhibitors

The proteasome represents an invaluable target for the treatment of cancer and autoimmune disorders. The application of proteasome inhibitors, however, remains limited to blood cancers because their reactive headgroups and peptidic scaffolds convey unfavorable pharmacodynamic properties. Thus, the discovery of more drug‐like lead structures is indispensable. In this study, we present the first structure of the proteasome in complex with an indolo‐phakellin that exhibits a unique noncovalent binding mode unparalleled by all hitherto reported inhibitors. The natural product inspired pentacyclic alkaloid binds solely and specificially into the spacious S3 subpocket of the proteasomal β5 substrate binding channel, gaining major stabilization through halogen bonding with the protein backbone. The presented compound provides an ideal scaffold for the structure‐based design of subunit‐specific nonpeptidic proteasome‐blockers.     

One-pot synthesis of 2-imidazolines via the ring expansion of imidoyl chlorides with aziridines

We herein report a simple and convenient one-pot synthesis of highly substituted 2-imidazolines in a regiocontrolled and stereospecific matter through the ring expansion reaction of an imidoyl chloride with an aziridine, analogous to the Heine reaction.