Reaktionen mit phosphororganischen verbindungen—XXI

An α‐Cyclopropanation of Carbonyl Derivatives by Oxidative Umpolung

“…The α‐functionalization of certain ketones through oxidative umpolung with iodine(III) was pioneered already in the 1960s, has been extensively investigated in the 1980s, and gained further attention in more recent years . It is believed that the reaction involves an enolonium species (compound 8 , Scheme a) .…”

“…Classically promoted by toxic elements such as Hg(II), [9,10] Tl(III), [9,11] Pb(IV), [9,12,13] or Se(IV) [14] more modern variants rely on Bi(V), [15] N-oxides, [16][17][18][19] Mn(III), [20,21] halosuccinimides, [22] sulfoxides, [23] and on iodine(III). [24][25][26][27][28][29] The a-functionalization of certain ketones through oxidative umpolung with iodine(III) was pioneered already in the 1960s, [30,31] has been extensively investigated in the 1980s, [32][33][34][35][36] and gained further attention in more recent years. [37][38][39][40][41] It is believed that the reaction involves an enolonium species (compound 8, Scheme 1 a).…”

Recent discoveries on the structure of iodine(iii) reagents and their use in cross-nucleophile coupling

“…The α-functionalization of ketones (and their derivatives) represents arguably one of the most powerful transformations induced by iodine( iii ) compounds ( Scheme 7 ). 23,24 It was already pioneered in the late 1960's, 96 but Mizukami et al were the first to describe the α-acetoxylation of simple ketones (acetophenones) with PhI(OAc) 2 in 1978. The reaction was generally low yielding and a mixture of acetic acid and acetic anhydride had to be used as the solvent.…”

Reactions of phosphorus ylides with acyl chlorides: pathways and preparative potential

“…Acylphosphoranes 8 can serve as intermediates in the syntheses of other classes of compounds, e.g., ketones, using alkaline hydrolysis, 15,18,70 reductive cleavage in the presence of zinc in acetic acid 18,20,68,71 or other methods. 18,26,69,72 Chlorination of phosphoranes 8 with dichloroiodobenzene followed by hydrolysis of salts 28 results in a-chloro ketones. 26 The ester group is introduced in alkylidenephosphorane molecules using alkyl chloroformates as acylating agents; 66,69,73 subsequent hydrolysis of the resulting phosphoranes 29 gives carboxylic acids.…”