Radical Carbodiazenylation – A Convenient and Effective Method to Achieve Carboamination of Non‐Activated Olefins

Abstract

The regioselective addition of aryl and aryldiazenyl substituents to olefinic substrates can be described as carbodiazenylation. In this report we present our final results relating to this unique type of radical functionalization reaction, which has now been developed into a convenient, versatile and highly effective synthetic method. Starting from an investigation into rate constants for the addition of aryl radicals to monosubstituted, non-activated olefins, this key step is shown to be both fast and selective in mixtures of dimethyl sulfoxide and water. The by-products obtained in earlier reactions reveal that the main complication of carbodiazenyl-

Mechanistic Analysis and Optimization of the Copper-Catalyzed Enantioselective Intramolecular Alkene Aminooxygenation

“…Based on these observations we concluded that the reaction most likely proceeds via direct capture of an sp 2 -hybridized carbon radical intermediate with TEMPO 18-21 (Scheme 1). The complete retention of the geometry of the isolated alkene indicates that the N-C bond formation is not reversible after C-Cu homolysis in this reaction.…”

“…m.p. 140-145 °C; [α] 21 D = −64.1 °(c = 2.0, CHCl 3 ); 1 H NMR (500 MHz, CDCl 3 ) δ 7.70 (s, 2H), 4.24 (dd, J = 12.5 Hz, 3.0 Hz, 1H), 3.84 (t, J = 8.0 Hz, 1H), 3.67 (s, 3H), 3.63 (m, 1H), 3.12 (AB quartet, J = 10.5 Hz, Δν = 20.6 Hz, 2H), 1.74 (m, 2H), 1.50-1.58 (m, 6H), 1.43 (s, 18H), 1.15 (s, 3H), 1.06 (s, 6H), 1.04 (s, 3H), 0.41 (s, 3H); 13 C NMR (75 MHz, CDCl 3 ) δ 163.2, 144.8, 131.6, 125.9, 79.9, 64.6, 61.5, 59.7, 58.1, 44.5, 39.6, 37.4, 36.0, 33.2, 31.7, 26.4, 25.7, 20.0, 17.1; IR (neat, thin film) ν 2955, 2874, 1471, 1453, 1405, 1349, 1253, 1225, 1165, 1125, 1042, 1008, 967, 920, 885, 812, 757, 710, 632, 595 cm −1 ; HRMS (ESI) calcd for [M+H] + C 31 H 55 O 4 N 2 S 1 : 551.3877, found: 551.3887.…”

Catalytic Enantioselective Alkene Aminohalogenation/Cyclization Involving Atom Transfer

“…An initial screen of several halogen sources (NBS, CBr 4 , NIS, I 2 , and 2,4,4,6-tetrabromocyclohexa-2,5-dienone) revealed that significant background aminohalogenation occurred under the reaction conditions in the absence of the [Cu( R , R )-Ph-box](OTf) 2 catalyst. Fortunately, however, we did find that 2-iodopropane [14] did not produce any aminoiodination product ( 4a ) under these reaction conditions in the absence of catalyst (Table 1, entry 1). When the reaction was carried out in the presence of the chiral catalyst (20 mol%) under these reaction conditions 2-iodomethylindoline 4a was obtained in 84% yield and with 70% enantiomeric excess (Table 1, entry 2).…”

Modern Developments in Aryl Radical Chemistry

“…Second, a nucleophilic alkyl radical 50 arises from the addition step, which is effectively trapped by electrophilic salt 48 to give azo compound 51. As a result of several improvements, the methodology is now applicable for a wide range of polar to non-polar alkenes with almost no restrictions on the substitution pattern of the diazonium salt [101,102]. Moderate diastereoselectivities have been obtained in first attempts with chiral auxiliaries [103].…”