Ene reactions of acyl nitroso intermediates with alkenes and their halocyclization

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

“…The combination of iron(II) phthalocyanines [ 34 – 35 ] or iron(II)/iron(III) chloride [ 36 – 38 ] and N -phenylhydroxylamine effect allylic amination reactions that are believed to follow a nitroso–ene mechanism. Similar reactions have been reported using copper salts and N -phenylhydroxylamine [ 39 ] or N -Boc-hydroxylamine [ 40 – 41 ], presumably via oxidation of the hydroxylamine to a nitroso species which then undergoes the nitroso–ene reaction.…”

“…Similar results were obtained using FeBPMEN ( 5 , 10 mol %) as catalyst, which yielded small amounts of 9 (8%) and 10 (2%) but not ketone 11 . In their work using copper(I) iodide to catalyse similar reactions, Iwasa et al conducted reactions at much higher concentrations of hydroxylamine and alkene (0.5 mmol BocNHOH and 0.75 mmol alkene in a total reaction volume of 1 mL) [ 40 ]. With this in mind, the FeBPMEN ( 5 ) reaction was repeated at 10-fold higher concentration (i.e., 1:1 BocNHOH/cyclohexene in a total reaction volume of 1 mL).…”

Nitrosocarbonyl release from O-substituted hydroxamic acids with pyrazolone leaving groups

“…[26][27][28] Recently, the aerobic oxidation of hydroxamic acids by metal catalysts under mild conditions has been developed as an efficient strategy for nitrosocarbonyl generation. [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] In general, however, the above methods are not suitable for HNO generation under physiological conditions. Herein, we report a novel class of nitrosocarbonyl donors that upon deprotonation and loss of the leaving group (Scheme 1, HX = pyrazolone) generate nitrosocarbonyl intermediates that can hydrolyze to release HNO under physiological conditions.…”

Developments in Nitrosocarbonyl Chemistry: Mild Oxidation of N-Substituted Hydroxylamines Leads to New Discoveries

“…23 The first reported example for the catalytic nitrosocarbonyl ene reaction was reported by Iwasa and co-workers in 2004. 24 While a number of transition-metal catalysts were used, the highest yields were achieved using copper(I) iodide (…”