144688-83-5Relevant articles and documents
Catalytic Synthesis of N-Heterocycles via Direct C(sp3)-H Amination Using an Air-Stable Iron(III) Species with a Redox-Active Ligand
Bagh, Bidraha,Broere, Dani?l L. J.,Sinha, Vivek,Kuijpers, Petrus F.,Van Leest, Nicolaas P.,De Bruin, Bas,Demeshko, Serhiy,Siegler, Maxime A.,Van Der Vlugt, Jarl Ivar
supporting information, p. 5117 - 5124 (2017/05/04)
Coordination of FeCl3 to the redox-active pyridine-aminophenol ligand NNOH2 in the presence of base and under aerobic conditions generates FeCl2(NNOISQ) (1), featuring high-spin FeIII and an NNOISQ radical ligand. The complex has an overall S = 2 spin state, as deduced from experimental and computational data. The ligand-centered radical couples antiferromagnetically with the Fe center. Readily available, well-defined, and air-stable 1 catalyzes the challenging intramolecular direct C(sp3)-H amination of unactivated organic azides to generate a range of saturated N-heterocycles with the highest turnover number (TON) (1 mol% of 1, 12 h, TON = 62; 0.1 mol% of 1, 7 days, TON = 620) reported to date. The catalyst is easily recycled without noticeable loss of catalytic activity. A detailed kinetic study for C(sp3)-H amination of 1-azido-4-phenylbutane (S1) revealed zero order in the azide substrate and first order in both the catalyst and Boc2O. A cationic iron complex, generated from the neutral precatalyst upon reaction with Boc2O, is proposed as the catalytically active species.
Diamine-free lithiation-trapping of N-Boc heterocycles using s-BuLi in THF
Barker, Graeme,Obrien, Peter,Campos, Kevin R.
supporting information; experimental part, p. 4176 - 4179 (2010/11/16)
A diamine-free protocol for the s-BuLi-mediated lithiation-trapping of N-Boc heterocycles has been developed. In the optimized procedure, lithiation is accomplished using s-BuLi in THF at -30 °C for only 5 or 10 min. Subsequent electrophilic trapping or transmetalation-Negishi coupling delivered a range of functionalized pyrrolidines, imidazolidines, and piperazines in 43-83% yield.
Reactivity and Enantioselectivity in the Reactions of Scalemic Stereogenic α-(N-Carbamoyl)alkylcuprates
Dieter, R. Karl,Oba, Gabriel,Chandupatla, Kishan R.,Topping, Chris M.,Lu, Kai,Watson, Rhett T.
, p. 3076 - 3086 (2007/10/03)
Stereogenic 2-(N-carbamoyl)pyrrolidinylcuprates prepared from scalemic (i.e., enantioenriched) N-Boc-2-lithiopyrrolidine and THF soluble CuCN·2LiCl react with vinyl iodides, vinyl triflates, β-iodo-α,β-enoates, propargyl mesylates, and allyl bromide to afford the substitution products with excellent enantioselectivity. Excellent enantiomeric ratios are obtained in the conjugate addition reactions with methyl vinyl ketone while low enantiomeric ratios can be achieved with acrylate esters using HMPA/TMSCl activation. Enantiomeric ratios vary with substrate substitution patterns and the observed enantioselectivities appear to be more a function of cuprate-electrophile reactivities than of the reaction type (e.g., substitution, conjugate addition). Low enantiomeric ratios are obtained with the α-(N-carbamoyl)benzylcuprates. The lithium-copper transmetalation and cuprate vinylation reactions proceed with retention of configuration.
