Cyano (CN) groups are equivalent to carbonyl as well as amino- and hydroxymethyl groups. Therefore, their catalytic introduction under metal catalysis is an important issue in synthetic organic chemistry. Ni-catalyzed hydrocyanation is one of the most well-investigated, powerful tools for installing a CN group. However, it is still difficult to control chemo- and regioselectivity. In this review, the author uses allenes to enable regio-, stereo-, and face-selective transformations to natural product synthesis and axial chirality transfer.

An ultra-performance liquid chromatography (UPLC) method was developed and validated for the quantification of linezolid, PNU-142300, and PNU-142586 in human plasma. After protein precipitation using acetonitrile, the protein-free supernatant was separated using reverse-phase chromatography using an ACQUITY UPLC HSS T3 column and monitored at 254 nm. p-Toluic acid was used as the internal standard. No interference peak was observed at the retention times of linezolid, PNU-142300, PNU-142586, and p-toluic acid from blank plasma. The calibration curve of linezolid was linear from 0.2 to 50.0 µg/mL (coefficient of determination (r²) > 0.9999) and those of PNU-142300 and PNU-142586 were linear from 0.2 to 20.0 µg/mL (r² > 0.9996 and > 0.9998, respectively). The intra- and inter-assay accuracy (%) and precision (relative standard deviation (RSD) %) of the three components were confirmed to meet the criteria of the U.S. Food and Drug Administration guidelines. Tests confirmed the stability of linezolid, PNU-142300, and PNU-142586 in plasma during three freeze-thaw cycles and long-term storage of frozen plasma for up to 30 d; in extracts they were stable in the UPLC autosampler for over 48 h at 4°C. Furthermore, plasma concentrations of linezolid, PNU-142300 and PNU-142586 in patients treated with linezolid could be measured using the UPLC method developed in this study. This assay would be a powerful tool for therapeutic drug monitoring and clinical pharmacokinetic/pharmacodynamic (PK/PD) analyses in the optimization of linezolid treatment.

Crystallization by pH adjustment, as a type of reaction crystallization, is a solid–liquid separation method widely used in the area of pharmaceutical and pharmaceutical intermediate manufacturing. On the other hand, 3-alkenyl cephem compound is a typical zwitterionic pharmaceutical intermediate that possesses both an amino group and a carboxylic acid group. Such structure affords three main pH regions in solution and results in difficulties using crystallization by pH adjustment for isolation. As a consequence, 3-alkenyl cephem compound is usually crystallized at the point away from the solubility curve, causing unrestricted nucleation and flocculation behavior for the deposited particles which is difficult to filtrate. In this study, the pK_a of 3-alkenyl cephem compound was intensively investigated to inhibit the nucleation. An optimal pH level point was also sought to make monodisperse particles. In particular, during crystallization by pH-modulation operation, the key point was identified to be the number of primary particles aggregated in the secondary particles. It was revealed that the increment number of primary particles led to the generation of larger monodisperse particles. This investigation, combined with solid–liquid equilibrium, enabled the acquisition of target species with good operability for filtration process. This present investigation becomes the prosperity in the zwitterion compound production that it has hardships to crystallize and filtrate.

Surugamides are a group of non-ribosomal peptides isolated from marine-derived Streptomyces. Surugamide A (1) and its closely related derivatives, surugamides B–E (2–5), are D-amino acid containing cyclic octapeptides with cathepsin B inhibitory activity. The D-isoleucine (Ile), the nonproteinogenic amino acid residue embedded in 1, is less common in natural peptides because a rare C_β-epimerization is required for its biosynthesis. Taking advantage of the synthetic route of 2 previously established by our group, we synthesized the cyclic octapeptide 1 containing D-Ile by solid phase peptide synthesis. The structure of 1 actually contains D-allo-Ile in place of D-Ile, which was corroborated by chemical syntheses and chromatographic comparisons.