Oxidative demercuration revisited

Hayes, Peter C.; Suthers, Bill D.; Kitching, William

doi:10.1016/s0040-4039(00)01001-7

Cited by 24 publications

(14 citation statements)

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“…Similar relative reactivity, however, has been previously observed in reactions of carbon radicals generated from organomercury hydrides. 19 It would have been difficult to predict the observed relative reactivity using independently determined rate constants reported for the reaction of carbon radicals with TEMPO and O 2 , respectively. 18b,c It is likely the concentration of O 2 at 110 ° C in PhCF 3 is very low, contributing to the result.…”

Section: Resultsmentioning

confidence: 99%

“…m.p. 100-105 °C; [α] 19 D = 66.0 °(c = 1.15, CHCl 3 ); 1 H NMR (500 MHz, CDCl 3 ) δ 7.69 (d, J = 8.0 Hz, 1H), 7.51 (s, 1H), 7.40 (s, 2H), 7.20 (m, 1H), 7.00 (d, J = 5.0 Hz, 2H), 4.25 (m, 1H), 3.99 (dd, J = 9.0 Hz, 3.5 Hz, 1H), 3.93 (dd, J = 8.0 Hz, 6.5 Hz, 1H), 2.72 (d, J = 15.5 Hz, 1H), 2.49 (dd, J = 15.5 Hz, 10.0 Hz, 1H), 1.22-1.38 (m, 6H), 1.18 (s, 18H), 1.14 (s, 3H), 1.10 (s, 3H), 0.96 (s, 3H), 0.85 (s, 3H); 13 C NMR (75 MHz, CDCl 3 ) δ 151.8, 142.3, 136.8, 133.1, 127.2, 126.6, 124.8, 124.4, 121.0, 117.8, 78.8, 60.9, 59.9, 39.5, 35.0, 33.0, 31.6, 31.2, 31.0, 19.9, 19.7, 17.0; IR (neat, thin film) ν 2965, 2870, 1598, 1478, 1461, 1360, 1360, 1314, 1247, 1170, 1024, 788, 758, 705, 622, 600 cm −1 ; HRMS (ESI) calcd for [M+H] + C 32 H 49 O 3 N 2 S 1 : 541.3458, found: 541.3461.…”

Section: Methodsmentioning

confidence: 99%

“…m.p. 40-45 °C; [α] 19 D = 140.6 °(c = 1.35, CHCl 3 ), ee = 91%, determined by HPLC [Regis ( S , S ) Whelk, 5% IPA/hexane, 1.0 mL/min, λ = 254 nm, t(major) = 15.00 min, t(minor) = 13.33 min]. 1 H NMR (500 MHz, CDCl 3 ) δ 7.75 (d, J = 7.5 Hz, 1H), 7.53 (s, 1H), 7.39 (s, 2H), 7.24 (d, J = 6.5 Hz, 1H), 7.03 (m, 2H), 4.23 (m, 1H), 3.68 (d, J = 6.0 Hz, 2H), 2.55 (d, J = 9.5 Hz, 2H), 2.17 (s, 1H), 1.22 (s, 18H); 13 C NMR (75 MHz, CDCl 3 ) δ 152.0, 141.5, 136.2, 132.5, 127.7, 127.0, 125.3, 124.9, 121.1, 118.3, 65.3, 63.5, 35.0, 31.1, 31.0; IR (neat, thin film) ν 3541, 2963, 2869, 1593, 1476, 1461, 1349, 1243, 1171, 1095, 1039, 958, 760 cm −1 ; HRMS (ESI) calcd for [M+Na] + C 23 H 31 O 3 N 1 Na 1 S 1 : 424.1917, found: 424.1925.…”

Section: Methodsmentioning

confidence: 99%

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

2012

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The catalytic asymmetric aminooxygenation of alkenes provides an efficient and straightforward approach to prepare chiral vicinal amino alcohols. We have reported a copper(II)-catalyzed enantioselective intramolecular alkene aminooxygenation, using (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) as the oxygen source, which results in the synthesis of chiral indolines and pyrrolidines. Herein we disclose that kinetics studies indicate the reaction is first order both in substrate and the [Cu(R,R)-Ph-bis(oxazoline)]OTf2 catalyst, and zero order in TEMPO. Furthermore, kinetic isotope effect studies support that the cis aminocupration step, the addition of N-Cu across the alkene, is the rate-limiting step. Subsequent formation of a carbon radical intermediate, and direct carbon radical trapping with TEMPO is the indicated mechanism for the C-O bond formation as suggested by a deuterium labeling experiment. A ligand screen revealed that C(4)-phenyl substitution on the bis(oxazoline) is optimal for high asymmetric induction. The size of the substrate’s N-sulfonyl group also influences the enantioselectivity of the reaction. The preparative scale catalytic aminooxygenation reaction (gram scale) was demonstrated and an unexpected dependence on reaction temperature was uncovered on the larger scale reaction.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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

2012

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“…(1), vide supra] with analogous intramolecular alkene amination reactions that proceed via trans ‐aminometallation18, 31, 32 (outer sphere) and cis ‐aminometallation18, 33–36 (inner sphere) mechanisms led us to postulate that, stereochemically, the copper‐promoted reaction is more similar to reactions that proceed through cis ‐aminometallation mechanisms than to those that proceed through trans ‐aminometallations. We proposed that the resulting organocopper(II) intermediate underwent CCu homolysis29, 37–39 to generate the carbon radical, and direct trapping of the radical with TEMPO40, 41 provided the observed aminooxygenation product (Scheme ). We proposed that the cis ‐pyrrolidine stereochemistry resulted from NC bond formation through either a chair‐ or boatlike transition state, both of which place the sterically demanding α‐ and N‐substituents on opposite sides of the ring 18…”

Section: Introductionmentioning

confidence: 99%

Evidence for Alkene cis‐Aminocupration, an Aminooxygenation Case Study: Kinetics, EPR Spectroscopy, and DFT Calculations

Paderes

Belding

Fanovic

et al. 2012

Chemistry A European J

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Alkene difunctionalization reactions are important in organic synthesis. We have recently shown that copper(II) complexes can promote and catalyze intramolecular alkene aminooxygenation, carboamination, and diamination reactions. In this contribution, we report a combined experimental and theoretical examination of the mechanism of the copper(II)-promoted olefin aminooxygenation reaction. Kinetics experiments revealed a mechanistic pathway involving an equilibrium reaction between a copper(II) carboxylate complex and the γ-alkenyl sulfonamide substrate and a rate-limiting intramolecular cis-addition of N–Cu across the olefin. Kinetic isotope effect studies support that the cis-aminocupration is the rate-determining step. UV/Vis spectra support a role for the base in the break-up of copper(II) carboxylate dimer to monomeric species. Electron paramagnetic resonance (EPR) spectra provide evidence for a kinetically competent N–Cu intermediate with a CuII oxidation state. Due to the highly similar stereochemical and reactivity trends among the CuII-promoted and catalyzed alkene difunctionalization reactions we have developed, the cis-aminocupration mechanism can reasonably be generalized across the reaction class. The methods and findings disclosed in this report should also prove valuable to the mechanism analysis and optimization of other copper(-II) carboxylate promoted reactions, especially those that take place in aprotic organic solvents.

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“…10 Oxidative-demercuration reaction of 17 with NaBH 4 -TEMPO-O 2 furnished the TEMPO adduct 18, 11 which was converted to the diol 19 by treatment of Zn/HOAc. Deprotection of PMP, Boc, and benzyl groups by CAN, 12 3 N HCl, and hydrogenation, respectively, converted 19 to 20.…”

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confidence: 99%

Hg(II) Reagent-Controlled Stereoselective Synthesis of 2,5-cis- and 2,5-trans-Polyhydroxylated Pyrrolidines

Chikkanna

Han²

2004

Synlett

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Stereoselectivity in the intramolecular amidomercuration reaction of 11, which could form 2,5-cis-and 2,5-trans-polyhydroxylated pyrrolidines, was found to be dependent on the nature of the Hg(II) salts used as well as on the stereochemistry and protection state of the hydroxyl group at the allylic carbon. Thus, the amidomercuration reaction of 11 with Hg(CF 3 CO 2 ) 2 led to the predominant formation of the 2,5-cis-polyhydroxylated pyrrolidine 16, while use of Hg(CF 3 SO 3 ) 2 generated the corresponding 2,5trans isomer 17. Isomers 16 and 17 were further elaborated to stereoselectively synthesize 2,5-dideoxy 2,5-imino-D-altritol and 2,5dideoxy 2,5-imino-D-galactitol (for 20 and 21), which are known to be potent D-galactosidase inhibitors.

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Oxidative demercuration revisited

Cited by 24 publications

References 7 publications

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

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

Evidence for Alkene cis‐Aminocupration, an Aminooxygenation Case Study: Kinetics, EPR Spectroscopy, and DFT Calculations

Hg(II) Reagent-Controlled Stereoselective Synthesis of 2,5-cis- and 2,5-trans-Polyhydroxylated Pyrrolidines

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