Tsuda M, Morita T, Fukuhara S, Nakamura H. Synthesis of 4-amino-5-allenylisoxazoles
via gold(I)-catalysed propargyl aza-Claisen rearrangement.
Org Biomol Chem 2021;
19:1358-1364. [PMID:
33475653 DOI:
10.1039/d0ob02544e]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Propargyl aza-Claisen rearrangement of 4-propargylaminoisoxazoles 1 proceeded in the presence of cationic gold(i) catalysts to give 4-amino-5-allenylisoxazoles 2 in good to high yields. The silyl group at the terminal alkyne and a cationic gold(i) catalyst bearing a sterically bulky ligand are essential for the generation of isolable allene intermediates. The N-protection of the generated 4-amino-5-allenylisoxazoles 2 allowed the isolation of 5-allenylisoxazoles 4 that have never been synthesized. N-Propargyl aniline 5 was successfully converted to the corresponding ortho-allenyl aniline 6 under the current reaction conditions.
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