Enantioselective Synthesis of Sulfinamidines via Asymmetric Nitrogen Transfer from N-H Oxaziridines to Sulfenamides.

Sulfinamidines are promising aza-S chiral building blocks in asymmetric synthesis and drug discovery. However, no report has documented their enantioselective synthesis. Here we present an enantioselective synthesis of sulfinamidines via electrophilic amination of sulfenamides using an enantiopure N-H oxaziridine.

A Sulfur Monoxide Surrogate Designed for the Synthesis of Sulfoxides and Sulfinamides.

Sulfur monoxide (SO) is a highly reactive species that cannot be isolated in bulk. However, SO can play a pivotal role as a fundamental building block in organic synthesis. Reported herein is the design and application of a sulfinylhydrazine reagent as an easily prepared sulfur monoxide surrogate.

One-Pot, Three-Component Assembly of Sulfides Using a Sulfoxide Reagent as a Sulfur Dication Equivalent.

We report a one-pot, three-component synthesis of sulfides by exploiting a sulfoxide reagent as a formal sulfur dication equivalent. Our protocol consists of three simple chemical operations involving two Grignard reagents and trimethylsilyl chloride (TMSCl) to sequentially form sulfenate anions, sulfenate esters, and sulfides. We demonstrate a wide range of Grignard reagents to be coupled, thereby allowing the modular, thiol-free synthesis of sulfides including dialkenyl and alkenyl-alkynyl sulfides.

A Sulfoxide Reagent for One-Pot, Three-Component Syntheses of Sulfoxides and Sulfinamides.

Sulfoxides and sulfinamides represent versatile sulfur functional groups found in ligands, chiral auxiliaries, and bioactive molecules. Canonical two-component syntheses, however, rely on substrates with a preinstalled C-S bond and impede efficient and modular access to these sulfur motifs. Herein is presented the application of an easily prepared, bench-stable sulfoxide reagent for one-pot, three-component syntheses of sulfoxides and sulfinamides.

An integrated console for capsule-based, automated organic synthesis.

The current laboratory practices of organic synthesis are labor intensive, impose safety and environmental hazards, and hamper the implementation of artificial intelligence guided drug discovery. Using a combination of reagent design, hardware engineering, and a simple operating system we provide an instrument capable of executing complex organic reactions with prepacked capsules. The machine conducts coupling reactions and delivers the purified products with minimal user involvement.

Breaking the Symmetry of a Compound by Isotopic Substitution: Synthesis and Stereochemical Assignment of Monodeuterated -Perhydroazulene.

We report the synthesis and absolute configuration of monodeuterated -perhydroazulene (-), which is a rare example of an isotopically chiral hydrocarbon whose synthesis and stereochemical analysis are known to be particularly difficult. The synthesis features nickel-boride-catalyzed deuteration that allowed formation of the diastereomerically pure -fused bicyclic system in -. The vibrational circular dichroism results are in excellent agreement with the computed spectrum at ωB97XD/aug-cc-pVTZ, allowing unambiguous assignment of the absolute configuration of -.

Absolute Configuration of -Perhydroazulene.

We present the absolute configuration (AC) determination of an alkane, -perhydroazulene (), that displays the naturally very common trans fused [5,7] ring system. We outline the first synthesis yielding enantiopure and the application of optical rotatory dispersion (ORD) and vibrational circular dichroism (VCD) techniques. The spectroscopic results are in excellent agreement with the computed ORD at B3LYP/6-311++G(2d,2p) and the computed VCD spectrum at B3LYP/6-311++G(d,p), providing an assignment of the AC as (,)-(+)-.

Synthesis and Conformational Analysis of Parent Perhydroazulenes Reveal an Energetically Preferred cis Ring Fusion.

Perhydroazulenes are common structural motifs in various terpene natural products. Herein, we present the synthesis of parent - and -perhydroazulenes. Conformational analysis performed with density functional theory (DFT, e.

Iterative Assembly of Polycyclic Saturated Heterocycles from Monomeric Building Blocks.

Polycyclic saturated heterocycles with predictable shapes and structures are assembled by iterative couplings of bifunctional stannyl amine protocol (SnAP) reagents and a single morpholine-forming assembly reaction. Combinations of just a few monomers enable the programmable construction of rotationally restricted, nonplanar heterocyclic arrays with discrete sizes and molecular shapes. The three-dimensional structures of these constrained scaffolds can be quickly and reliably predicted by DFT calculations and the target structures immediately decompiled into the constituent building blocks and assembly sequences.

Synthesis and stabilities of peptide-based [1]rotaxanes: molecular grafting onto lasso peptide scaffolds.

The chemical synthesis of peptide-based [1]rotaxanes (lasso peptides) was achieved by [2]rotaxane formation followed by two chemoselective ligation reactions. Our approach enabled incorporation of various peptide sequences into a common rotaxane structure. The synthetic lasso peptides were characterized by NMR, chromatography, and partial degradation by proteases.

Critical evaluation and rate constants of chemoselective ligation reactions for stoichiometric conjugations in water.

Chemoselective ligation reactions have contributed immensely to the development of organic synthesis and chemical biology. However, the ligation of stoichiometric amounts of large molecules for applications such as protein-protein conjugates is still challenging. Conjugation reactions need to be fast enough to proceed under dilute conditions and chemoselective in the presence of unprotected functional groups; the starting materials and products must be stable under the reaction conditions.

Contribution of the mannan backbone of cryptococcal glucuronoxylomannan and a glycolytic enzyme of Staphylococcus aureus to contact-mediated killing of Cryptococcus neoformans.

The fungal pathogen Cryptococcus neoformans is killed by the bacterium Staphylococcus aureus, and the killing is inhibited by soluble capsular polysaccharides. To investigate the mechanism of killing, cells in coculture were examined by scanning and transmission electron microscopy. S.

Killing of cryptococcus neoformans by Staphylococcus aureus: the role of cryptococcal capsular polysaccharide in the fungal-bacteria interaction.

Microbes compete for the environmental niche which is their host. To investigate the effects of a pathogenic bacterium on invasion and colonization by a pathogenic yeast, Cryptococcus neoformans was co-cultured with Staphylococcus aureus. We found that the number of colony forming units of C.