Recent developments in asymmetric catalytic addition to CN bonds

Asymmetric aziridination of N-tert-butanesulfinyl imines with phenyldiazomethane via sulfur ylides

“…We thus turned our attention to the sulfur ylidemediated reaction that involves an in-situ conversion of the diazo compound into the more reactive sulfur ylide, under neutral conditions, in the presence of a transition metal catalyst and a sulfide. Aziridine formation still failed to occur from the reactions of either EDA or TMSD with 1a in the presence of catalytic amounts of Rh 2 (OAc) 4 and tetrahydrothiophene (THT). However, we were pleased to observe that when PDM was reacted with 1a, in dichloromethane at room temperature in the presence of 1 mol% Rh 2 (OAc) 4 and 50 mol% THT, the corresponding aziridines 3a were formed in quantitative yield (entry 1 in Table 1).…”

“…Aziridine formation still failed to occur from the reactions of either EDA or TMSD with 1a in the presence of catalytic amounts of Rh 2 (OAc) 4 and tetrahydrothiophene (THT). However, we were pleased to observe that when PDM was reacted with 1a, in dichloromethane at room temperature in the presence of 1 mol% Rh 2 (OAc) 4 and 50 mol% THT, the corresponding aziridines 3a were formed in quantitative yield (entry 1 in Table 1). Under otherwise identical conditions, lowering the reaction temperature was found to have little effect on the diastereoselectivity and it led to a lower conversion of the imine (entry 2 in Table 1).…”

“…for C 20 H 23 NOS: C,73.81;H,7.12;N,4.30. Found: C,73.42;H,7.07;N,4. 10H),6.79 (d,J = 15.6 Hz,1H),6.37 (dd,J = 15.6 Hz,J = 9.3 Hz,1H),3.83 (d,J = 3.6 Hz,1H),3.23 (d,J = 7.2 Hz, 1H), 1.19 (s, 9H); 1 H NMR (500 MHz,CDCl 3,2H),2H),5H),1H),6.79 (d,J = 15.5 Hz,1H),6.38 (dd,J = 15.5 Hz,J = 9.5 Hz,1H),3.85 (d,J = 3.5 Hz,1H),3.23 (dd,J = 9.5 Hz, J = 3.5 Hz, 1H), 1.19 (s, 9H); 13 C NMR (125 MHz,CDCl 3 ,136.50,135.75,128.58,128.50,127.98,127.73,126.47,126.39,123.51,57.21,…”

“…Among the precursors used in asymmetric aziridine syntheses, imines have served as highly convenient starting materials due to their ease of synthesis (or in situ generation) and their relative reactivity. 4 In one approach beginning with imines, an asymmetric Corey-Chaykovskytype reaction has been developed utilizing achiral sulfur ylides and readily available asymmetric N-sulfinyl imines. [5][6][7] However, this approach generally requires use of strong base to generate the ylide and therefore suffers associated limitations.…”

Retracted: Enantioselective Radical Addition to Ketimines: A Synthetic Route Towards α,α‐Disubstituted α‐Amino Acids

“…[1] However, these reactions are limited because they employ highly basic nucleophiles that often cause side reactions. An alternative approach is the use of radical addition reactions to provide neutral reaction conditions and functional-group compatibility.…”