Triquinanes from Linear Alkylidene Carbenes via Trimethylenemethane Diyls

The intramolecular [2+3] cycloaddition reaction of the trimethylenemethane diyl generated from the intramolecular cyclopropanation reaction of alkylidene carbene produced linearly fused triquinanes regio- and stereoselectively. The current tandem cycloaddition reaction was applied to a 14-step total synthesis of hirsutene from methallyl alcohol

Total Synthesis of Panaginsene with Structural Revision

A facile total synthesis of the reported structure for panaginsene through a trimeth­ylene­methane (TMM) diyl mediated tandem cycloaddition reaction revealed that the spectroscopic data of the synthesized structure did not match with the data of the natural product. The total synthesis of the stereoisomer of the reported structure confirmed that the correct structure of panaginsene was the 11-<i>epi</i> stereoisomer of the originally proposed structure of panaginsene

A Facile Construction of the Quadranoid Skeleton: Application to the Total Synthesis of (±)-Suberosenone

A tandem free radical cyclization−rearrangement sequence was designed and executed to produce tricyclo[4.3.2.01,5]undecane 7 from cyclopentene 6A in a single operation. The total synthesis of suberosenone was accomplished from 7

A Stereoselective Enyne Cross Metathesis

Intermolecular enyne metathesis reaction of alkynes with olefins catalyzed by second-generation Grubbs catalyst (1) proceeded stereoselectively under ethylene atmosphere to produce 1,3-disubstituted butadienes with E stereochemistry

Anhydrous Hydration of Nitriles to Amides using Aldoximes as the Water Source

Anhydrous hydrolysis of nitriles to amides was developed using acetaldoxime as the water source in the presence of Rh catalyst. Conversion of various nitriles to amides was performed under neutral and anhydrous conditions, and the reaction displays excellent compatibility with acid or base labile and hydrolytically labile functional groups

Tandem Cycloaddition Reactions of Allenyl Diazo Compounds Forming Triquinanes via Trimethylenemethane Diyls

A tandem reaction strategy for forming triquinanes from linear allenyl diazo compounds through an intramolecular 1,3-dipolar cycloaddition reaction of an allenyl diazo group that generates a trimethylenemethane (TMM) diyl followed by an intramolecular [2 + 3] TMM diyl cycloaddition reaction has been developed. The new tandem cycloaddition reaction is readily applicable to the synthesis of complex molecules with high versatility and efficiency

One-Pot Three-Component Tandem Metathesis/Diels−Alder Reaction

A tandem enyne, diene-ene metathesis reaction followed by Diels−Alder reaction accomplished a stereoselective three-component reaction protocol with four stereocenters

Angularly Fused Triquinanes from Linear Substrates through Trimethylenemethane Diyl [2 + 3] Cycloaddition Reaction

Angularly fused triquinanes were synthesized from linear dienes and phenyl(propynyl)iodonium salt through trimethylenemethane (TMM) diyl mediated [2 + 3] cycloaddition reaction. TMM diyl intermediates were obtained from alkylidene carbenes generated from reactions of alkynyliodonium salts with nucleophiles

Sulfhydryl-Specific Probe for Monitoring Protein Redox Sensitivity

Reactive oxygen species (ROS) regulate various biological processes by modifying reactive cysteine residues in the proteins participating in the relevant signaling pathways. Identification of ROS target proteins requires specific reagents that identify ROS-sensitive cysteine sulfhydryls that differ from the known alkylating agents, iodoacetamide and <i>N</i>-ethylmaleimide, which react nonspecifically with oxidized cysteines including sulfenic and sulfinic acid. We designed and synthesized a novel reagent, methyl-3-nitro-4-(piperidin-1-ylsulfonyl)­benzoate (NPSB-1), that selectively and specifically reacts with the sulfhydryl of cysteines in model compounds. We validated the specificity of this reagent by allowing it to react with recombinant proteins followed by peptide sequencing with nanoUPLC-ESI-q-TOF tandem mass spectrometry (MS/MS), and mutant studies employed it to identify cellular proteins containing redox-sensitive cysteine residues. We also obtained proteins from cells treated with various concentrations of hydrogen peroxide, labeled them with biotinylated NPSB-1 (NPSB-B), pulled them down with streptavidin beads, and identified them with MS/MS. We grouped these proteins into four families: (1) those having reactive cysteine residues easily oxidized by hydrogen peroxide, (2) those with cysteines reactive only under mild oxidative stress, (3) those with cysteines reactive only after exposure to oxidative stress, and (4) those with cysteines that are reactive regardless of oxidative stress. These results confirm that NPSBs can serve as novel chemical probes for specifically capturing reactive cysteine residues and as powerful tools for measuring their oxidative sensitivity and can help to understand the function of cysteine modifications in ROS-mediated signaling pathways