Premium
Iron‐Catalysed Remote C(sp 3 )−H Azidation of O ‐Acyl Oximes and N ‐Acyloxy Imidates Enabled by 1,5‐Hydrogen Atom Transfer of Iminyl and Imidate Radicals: Synthesis of γ‐Azido Ketones and β‐Azido Alcohols
Author(s) -
TorresOchoa Rubén O.,
Leclair Alexandre,
Wang Qian,
Zhu Jieping
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901079
Subject(s) - chemistry , hydrolysis , catalysis , azide , hydrogen atom , trimethylsilyl azide , redox , trimethylsilyl , medicinal chemistry , nitrogen atom , carbon fibers , nitrogen , carbon atom , hydrogen , organic chemistry , group (periodic table) , ring (chemistry) , materials science , composite number , composite material
In the presence of a catalytic amount of iron(III) acetylacetonate [Fe(acac) 3 ], the reaction of structurally diverse ketoxime esters with trimethylsilyl azide (TMSN 3 ) afforded γ‐azido ketones in good to excellent yields. This unprecedented distal γ‐C(sp 3 )−H bond azidation reaction went through a sequence of reductive generation of an iminyl radical, 1,5‐hydrogen atom transfer (1,5‐HAT) and iron‐mediated redox azido transfer to the translocated carbon radical. TMSN 3 served not only as a nitrogen source to functionalise the unactivated C(sp 3 )−H bond, but also as a reductant to generate the catalytically active Fe II species in situ. Based on the same principle, a novel β‐C(sp 3 )−H functionalisation of alcohols via N ‐acyloxy imidates was subsequently realised, leading, after hydrolysis of the resulting ester, to β‐azido alcohols, which are important building blocks in organic and medicinal chemistry.