Ruffell, Katie; Smith, Frances R.; Green, Michael T.; Nicolle, Simon M.; Inman, Martyn; Lewis, William; Hayes, Christopher J.; Moody, Christopher J. published their research in Chemistry – A European Journal in 2021. The article was titled 《Diazophosphonates: Effective Surrogates for Diazoalkanes in Pyrazole Synthesis》.Formula: C4H7BrO2 The article contains the following contents:
Diazophosphonates, readily prepared from α-ketophosphonates by oxidation of the corresponding hydrazones in batch or in flow, are useful partners in 1,3-dipolar cycloaddition reactions to alkynes to give N-H pyrazoles, including the first intramol. examples of such a process. The phosphoryl group imbues a number of desirable properties into the diazo 1,3-dipole. The electron-withdrawing nature of the phosphoryl stabilizes the diazo compound making it easier to handle, while the ability of the phosphoryl group to migrate readily in a [1,5]-sigmatropic rearrangement enables its transfer from C to N to aromatize the initial cycloadduct, and hence its facile removal from the final pyrazole product. Overall, the diazophosphonate acts as a surrogate for the much less stable diazoalkane in cycloadditions, with the phosphoryl group playing a vital, but traceless, role. The cycloaddition proceeds more readily with alkynes bearing electron-withdrawing groups, and is regiospecific with asym. alkynes. The potential of diazophosphonates for use in bioorthogonal cycloadditions is demonstrated by their facile addition to strained alkynes. In the experimental materials used by the author, we found 4-Bromobutanoic acid(cas: 2623-87-2Formula: C4H7BrO2)
4-Bromobutanoic acid(cas: 2623-87-2) belongs to carboxylic acids. The chief chemical characteristic of the carboxylic acids is their acidity. They are generally more acidic than other organic compounds containing hydroxyl groups but are generally weaker than the familiar mineral acids (e.g., hydrochloric acid, HCl, sulfuric acid, H2SO4, etc.).Formula: C4H7BrO2
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary