Direct Synthesis of Allylic Thioethers Under Greener Conditions: A Solvent- and Catalyst-Free Approach

We present herein a new catalyst-free and solvent-free approach for the synthesis of allylic thioethers directly from allylic alcohols and thiols. The methodology allows the synthesis of different allylic thioethers in good to excellent yields under microwave irradiation. Theoretical calculations for the allylic carbocation helped to explain the regioselectivity observed when nonsymmetric substrates are used in the reaction.     

The Inducible Intein-Mediated Self-Cleaving Tag (IIST) System: A Novel Purification and Amidation System for Peptides and Proteins

An efficient self-cleavable purification tag could be a powerful tool for purifying recombinant proteins and peptides without additional proteolytic processes using specific proteases. Thus, the intein-mediated self-cleavage tag was developed and has been commercially available as the IMPACT™ system. However, uncontrolled cleavages of the purification tag by the inteins in the IMPACT™ system have been reported, thereby reducing final yields. Therefore, controlling the protein-splicing activity of inteins has become critical. Here we utilized conditional protein splicing by salt conditions. We developed the inducible intein-mediated self-cleaving tag (IIST) system based on salt-inducible protein splicing of the MCM2 intein from the extremely halophilic archaeon, Halorhabdus utahensis and applied it to small peptides. Moreover, we described a method for the amidation using the same IIST system and demonstrated ¹⁵N-labeling of the C-terminal amide group of a single domain antibody (V_HH).     

Copper-catalyzed one-pot synthesis of imidazo/benzoimidazoquinazolinones by sequential Ullmann-type coupling and intramolecular C-H amidation

A simple, practical, and highly efficient copper-catalyzed one-pot synthesis of imidazo/benzoimidazoquinazolinones has been developed. The procedure is based on a sequential copper-catalyzed Ullmann-type N-arylation and aerobic oxidative intramolecular C-H amidation. This method should provide a new and useful strategy for construction of N-heterocycles.     

Aerobic oxidation of secondary benzylic alcohols and direct oxidative amidation of aryl aldehydes promoted by sodium hydride

We reported herein new reactivities and possible mechanistic implications of a simplest oxidant (NaH/air) uncovered on a broad range of useful transformations, including aerobic alcohol oxidations, allylic alcohol isomerizations and oxidations, cyclopropyl alcohol fragmentations, and direct aryl aldehyde oxidative amidations. These readily implementable transition-metal-free processes feature exceptional material accessibility, operational simplicity, and environmental compatibility, and add new dimensions to its synthetic utilities that are fairly robust yet had not previously been fully realized and systematically explored.     

The synthesis of C-13 functionalized pleuromutilins via C-H amidation and subsequent novel rearrangement product

Multi-gram quantities of C-13 functionalized pleuromutilin intermediates were synthesized under mild conditions via C-H amidation chemistry. The initial work was performed using rhodium catalysis. However, the highest yields were achieved using silver catalysis, resulting in stereoselective oxazolidinone formation. The ring closure was performed in the presence of a C-12 vinyl group, which differentiates it from historical methods involving the saturated pleuromutilin skeleton. A highlight of this vinyl template is a unique tetracyclic rearrangement product that can be generated from its treatment with hydrochloric acid and heat.     

4-Hydroxy-2-quinolones 132. Synthesis, chemical, and biological properties of 1-R-4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acids 2-nitrobenzylidenehydrazides

1-R-4-Hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acids 2-nitrobenzylidenehydrazides are reduced to the corresponding quinoline-3-carboxamides by zinc in glacial acetic acid but in refluxing triethylphosphite they are converted to the symmetrical N,N′-di(4-hydroxy-2-oxo-1,2-dihydro-3-quinolinoyl)hydrazines. A study of the antitubercular activity of the synthetic compounds has been carried out. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1687–1692, November, 2007.     

Catalyst-Free,Direct, High Regio- and Chemoselective Conversion of Epoxides to Vicinal Haloesters Under Mild,Neutral, and Solvent-Free Conditions

Abstract

A catalyst-free, high regio- and chemoselective method is described for the mild conversion of wide varieties of epoxides directly to their corresponding vicinal haloesters using quaternary ammonium halides R₄N⁺X^- (X equals; Cl, Br, I; R = n-butyl, n-pentyl, n-hexyl) in the presence of an aliphatic or aromatic carboxylic anhydride at room temperature under neutral and solvent-free conditions.