A Modular Olefination of Aldehydes with Thiols as Coupling Partners.

Olefins range amongst the most important motifs in organic chemistry. Hence, the development of novel olefin syntheses has remained a constant field of research in synthetic chemistry to date. Herein, we report the development of a modular olefination that converts aldehydes into olefins with thiols as reaction partners. The simple, transition metal-free protocol proceeds via an unsymmetrical bissulfone intermediate which is converted into the respective alkene in a Ramberg-Bäcklund-type process. Differently substituted olefins can be synthesized from readily available starting materials in typically good yields and stereoselectivities using basic laboratory chemicals exclusively. Complementary reaction conditions differing in the choice of solvent favor the E/Z-products respectively under kinetic control rendering this protocol an interesting economical addition to the family of olefin syntheses.

Direct Synthesis of Unsymmetrical Dithioacetals.

Sabine Bognar and Manuel van Gemmeren from the WWU Münster have been invited to contribute the cover of this issue. The image depicts a volcano to symbolize the general theme of sulfur chemistry, whereas the piles of rubble reflect the selectivity of the reaction. Read the full text of the article at 10.1002/chem.202004835.

Direct Synthesis of Unsymmetrical Dithioacetals.

Dithioacetals are a frequently used motif in synthetic organic chemistry and have recently seen increasing attention as structural motif in promising antiviral agents against plant pathogens. Most existing reports, however, only discuss symmetrical dithioacetals. Examples of mixed dithioacetals are scarce and no general method for the selective synthesis of these compounds exists. Herein, a synthetically simple general one-step protocol was developed for the synthesis of a broad range of unsymmetrical dithioacetals consisting of one aromatic and one aliphatic thiol moiety from the corresponding aldehyde/thiol mixture. The mixed S,S-acetals were obtained in high yields, and a great variety of functional groups was tolerated. Kinetic control enabled an excellent selectivity in regard to the unsymmetrical dithioacetal.

The Direct Conversion of α-Hydroxyketones to Alkynes.

Alkynes are highly important functional groups in organic chemistry, both as part of target structures and as versatile synthetic intermediates. In this study, a protocol for the direct conversion of α-hydroxyketones to alkynes is reported. In combination with the variety of synthetic methods that generate the required starting materials by forming the central C-C bond, it enables a highly versatile fragment coupling approach toward alkynes. A broad scope for this novel transformation is shown alongside mechanistic insights. Furthermore, the utility of our protocol is demonstrated through its application in concert with varied α-hydroxyketone syntheses, giving access to a broad spectrum of alkynes.

Multiplexed antibody detection from blood sera by immobilization of in vitro expressed antigens and label-free readout via imaging reflectometric interferometry (iRIf).

The detection of antibodies from blood sera is crucial for diagnostic purposes. Miniaturized protein assays in combination with microfluidic setups hold great potential by enabling automated handling and multiplexed analyses. Yet, the separate expression, purification, and storage of many individual proteins are time consuming and limit applicability. In vitro cell-free expression has been proposed as an alternative procedure for the generation of protein assays. We report the successful in vitro expression of different model proteins from DNA templates with an optimized expression mix. His10-tagged proteins were specifically captured and immobilized on a Ni-NTA coated sensor surface directly from the in vitro expression mix. Finally, the specific binding of antibodies from rabbit-derived blood sera to the immobilized proteins was monitored by imaging reflectometric interferometry (iRIf). Antibodies in the blood sera could be identified by binding to the respective epitopes with minimal cross reactivity. The results show the potential of in vitro expression and label-free detection for binding assays in general and diagnostic purposes in specific.

Palladium-Catalyzed Synthesis of 2-Cyanoindoles from 2-gem-Dihalovinylanilines.

An efficient Pd(0)-catalyzed synthesis of 2-cyanoindoles from 2-gem-dihalovinylanilines is reported. Few methods have aimed to synthesize these scaffolds, which are found in many natural products and have high bioactivity. This protocol features a robust catalyst system utilizing Zn(TFA)2 to prolong the catalytic activity. Additionally, the amount of cyanide in the reaction phase is minimized by taking advantage of the solubility of Zn(CN)2 in a two-solvent mixture.