Cheng, You-Song; Chan, Shih-Hsien; Rao, Gunda Ananda; Gurubrahamam, Ramani; Chen, Kwunmin published an article in 2021. The article was titled 《Enantioselective Aza-Friedel-Crafts Reaction of Heteroarenes with in situ Generated Isoxazolium Ions via Chiral Phosphoric Acid Catalysis》, and you may find the article in Advanced Synthesis & Catalysis.Application In Synthesis of N-tert-Butoxycarbonylhydroxylamine The information in the text is summarized as follows:
An asym. organocatalytic aza-Friedel-Crafts reaction was developed to give the enantioenriched isoxazolines I [R = Et, i-Pr, Bn, etc.; R1 = Boc, Cbz; Ar = Ph, 4-BrC6H4, 2-thienyl, etc.; Ar1 = indol-3-yl, pyrrol-2-yl, 5-methyl-pyrrol-2-yl, etc.] bearing a quaternary-substituted stereogenic center in good-to-excellent yields and enantioselectivity (50-99%, 55->99% ee). This protocol involved the in situ generated isoxazolium ions in the presence of a chiral phosphoric acid followed by the heteroarene addition through asym. counteranion-directed catalysis. In the part of experimental materials, we found many familiar compounds, such as N-tert-Butoxycarbonylhydroxylamine(cas: 36016-38-3Application In Synthesis of N-tert-Butoxycarbonylhydroxylamine)
N-tert-Butoxycarbonylhydroxylamine(cas: 36016-38-3) belongs to anime. Primary amines having a tertiary alkyl group (R3CNH2) are difficult to prepare with most methods but are made industrially by the Ritter reaction. In this method a tertiary alcohol reacts with hydrogen cyanide (HCN) in the presence of a concentrated strong acid; a formamide, RNH―CHO, is formed first, which then undergoes hydrolysis.Application In Synthesis of N-tert-Butoxycarbonylhydroxylamine
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