RESUMEN
Despite the widespread utilizable value of 3-oxazolines, mild and efficient access to such a class of unique structures still remains, to date, a challenge. Herein, we present a [3 + 2] annulation strategy, guided by the retrosynthetic principle of [CO + CCN], that utilizes vinyl azides as the CCN module and aldehydes as the CO module. This approach enables the efficient construction of the 3-oxazoline framework with remarkable features, including operational simplicity, environmental friendliness, and high efficiency. Notably, it solely requires the addition of inexpensive and readily available N-hydroxyphthalimide (NHPI) and air oxygen to obtain the desired product. It also provides a new way to generate the hydroxyl radical, which is produced by the homolysis of peroxycarboxylic acid. In addition, control experiments, X-ray crystallographic analysis, high-resolution mass spectrometry (HRMS), and density functional theory (DFT) calculations afford evidence for the key intermediates (hydroxyl radical, carboxyl radical, imine radical, hydroxyl substituted amide derivatives), further confirming the path for realization of 3-oxazolines.
RESUMEN
The radical relay provides an effective paradigm for intermolecular assembly to achieve functionalization across remote chemical bonds. Herein, we report the first radical relay 1,3-carbocarbonylation of α-carbonyl alkyl bromides across two separate CâC bonds. The reaction is highly chemo- and regioselective, with two C(sp3)-C(sp3) bonds and one CâO bond formed in a single orchestrated operation. In addition, the synthesis method under mild conditions and using inexpensive copper as the catalyst allows facile access to structurally diverse 1,3-carbocarbonylation products. The plausible mechanism is investigated through a series of control experiments, including radical trapping, radical clock experiments, critical intermediate trapping, and 18O labeling experiment.
RESUMEN
The high-efficiency phosphate solubilizing mutants of Penicillium oxalicum YTY were screened by mutagenesis of ion beam combined with UV. We analyzed the changes and correlation of phosphate solubilizing ability, pH, and organic acid for YTY and its mutants, and examined the phosphate solubilizing mechanism of P. oxalicum YTY. The results showed that five high-efficiency mutants, P9-8, P9-9, P15-4, P15-6, and P15-7 were screened, and that the phosphate solubili-zing ability of mutants was increased by more than 60% compared with YTY. In the process of pho-sphorus solubilization, both phosphorus solubilizing ability and rate of mutants were higher than that of YTY, and the mutants pH was significantly lower than YTY. The type and content of organic acids secreted by the mutants showed some variations. All mutants and YTY could secrete lactic acid, acetic acid and oxalic acid, while P9-8 also produced citric acid. The pH and the phosphate solubilizing ability of YTY and its mutants had a significant negative correlation. Phosphate solubilizing ability with organic acid and pH were all significantly correlated for YTY and the mutants, except P15-4. Organic acids and low environmental pH reduced by organic acids were the probable mechanism for P. oxalicum to dissolve phosphorus. Radiation of ion beam combined with UV could change the type and content of organic acids of P. oxalicum YTY, and initiate other H+ releasing pathways to lower pH, and participate phosphorus dissolution. The study provided biological mate-rials and theoretical basis for the research and development of high-efficiency phosphate solubilizing P. oxalicum and understanding the phosphate solubilizing mechanism of P. oxalicum.