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The Preparation of N ‐ tert ‐Butyloxycarbonyl‐(Boc‐)Protected Sulfoximines and Sulfimines by an Iron(II)‐Mediated Nitrene Transfer from BocN 3 to Sulfoxides and Sulfides
Author(s) -
Bach Thorsten,
Körber Christina
Publication year - 1999
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199905)1999:5<1033::aid-ejoc1033>3.0.co;2-1
Subject(s) - nitrene , chemistry , reagent , yield (engineering) , azide , steric effects , nucleophile , medicinal chemistry , sulfoxide , ligand (biochemistry) , reactive intermediate , trimethylindium , sulfur , organic chemistry , catalysis , metalorganic vapour phase epitaxy , biochemistry , materials science , receptor , epitaxy , layer (electronics) , metallurgy
The imidation of sulfides and sulfoxides to the corresponding sulfimides and sulfoximides was carried out with N ‐ tert ‐butyloxycarbonyl azide (BocN 3 ) in the presence of FeCl 2 . Sulfoxides 1 reacted at room temperature in CH 2 Cl 2 to give the corresponding sulfoximides 3 in 40–95% yield. The imidation of the sterically congested substrate tert ‐butyl methyl sulfoxide ( 1f ) proceeded sluggishly (10% yield). The sterospecificity of the reaction was demonstrated with the enantiomerically enriched substrates ( R )‐(+)‐ 1b and ( S )‐(–)‐ 1d which yielded the sulfoximides ( R )‐(+)‐ 3b and ( S )‐(–)‐ 3d with retention of configuration. Mechanistically, an intermediate (nitrene)Fe IV complex is postulated as the reactive nitrene transfer reagent which is formed from FeCl 2 and BocN 3 . The more nucleophilic sulfides 2 reacted more readily in the imidation than sulfoxides. Their conversion to the corresponding sulfimides 4 was conducted with BocN 3 and a substoichiometric amount of FeCl 2 (0.25 equiv.). Yields ranged between 44 and 92%. In an alternative reaction mode, BocN 3 was utilized at 0°C in the presence of FeCl 2 and acetyl acetone. The sulfimidation, which did not otherwise occur at this temperature, was accelerated by the ligand (36–90% yield).