α-Bromination of primary nitriles

Stevens, Calvin L.; Holland, W. J.

doi:10.1021/jo50015a007

Cited by 10 publications

(2 citation statements)

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“…The halides 3j, 1, m, v, w (Fluka, purum), 3k, n (Fluka, pract.), 3h (Du Pont), and 3i (Aldrich, 98 %)were used as received. Halide 3u was prepared according to the method of Steuens and Holland [48]. Vitamin B,,, (1; hydroxocob(II1)alamin hydrochloride, OHChl"'.HCI; pyrogen-free Fr.…”

Section: Experimental Partmentioning

confidence: 99%

Influence of the Axial Alkyl Ligand on the Reduction Potential of Alkylcob(III)alamins and Alkylcob(III)yrinates

Zhou

Tinembart

Scheffold

et al. 1990

Helvetica Chimica Acta

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The irreversible-reduction potentials of 26 alkylcob(II1)alamins (RCbl"'; la-z) and 26 alkylcob(I1I)yrinates (RCby'"'; 2a-2) (E, la-z and Ep 2a-2, resp.) have been measured in situ by single-scan voltammetry of hydroxocob(II1)alamin hydrochloride (vitamin BIZb. HCl; 1) or heptamethyl cob(1I)yrinate perchlorate (ClO.,'Cby'"; 2) in presence of the corresponding alkyl halides (RX; 3-2) in DMF. The reduction potentials of alkylcobalt complexes exhibiting half-life times as short as a few seconds become measurable by this technique. Thermodynamic cycles prove that the observed reduction potentials are closely related to the standard reduction potentials E"(R-Co"' + eC%R' + Co'). Electron-withdrawing groups and/or an increased degree of substitution at the Co-bound C-atom in RCbl"' and RCby'"' shift E,(la-z) and E (2a-2) towards positive potentials. Linear correlations have been found between Ep(la-z) (EP(2a-z)) of RCbl" (R'Cby'"') and the pK, of RH (or the Tuft v*-or the Hummeft o--values of R) within each class of R, i.e. MeCbl"' (Me'Cby'"'), primary RCbl"' (RCby'"') and secondary RCbll'P(R'Cby'"L). The correlations allow to distinguish between electronic effects of the Co-bound alkyl residues and their steric interactions with the corrin side chains. The correlations have further been used to visualize the light-induced formal insertion of an olefin into the Co,C-bond of an alkylcobalamin (Scheme 2, la-lu), a key step in the vitamin-B,,-catalized C,C-bond formation.

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Section: Experimental Partmentioning

confidence: 99%

Influence of the Axial Alkyl Ligand on the Reduction Potential of Alkylcob(III)alamins and Alkylcob(III)yrinates

Zhou

Tinembart

Scheffold

et al. 1990

Helvetica Chimica Acta

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“…Diastereoselective Alkylations of C -Metalated Nitriles. The requisite phenethyl-containing nitrile 10 was readily synthesized by alkylating propionitrile ( 13a ) with racemic phenethyl bromide and brominating the resulting nitrile 14a (Scheme ). Conversion of 10 to the corresponding C -magnesiated nitrile 11 featured an in situ alkylation procedure 18b in which a solution of i- PrMgCl was added to a −78 °C THF solution of the bromonitrile 10 and methyl cyanoformate.…”

Section: Resultsmentioning

confidence: 99%

Metalated Nitriles: Internal 1,2-Asymmetric Induction

et al. 2008

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Alkylations of conformationally constrained acyclic nitriles containing vicinal dimethyl groups and an adjacent phenyl group or trisubstituted alkene are exceptionally diastereoselective. Probing the alkylation stereoselectivity with a series of C- and N-metalated nitriles implicates a reactive conformation in which an sp2-hybridized substituent projects over the metalated nitrile to avoid allylic strain. Steric screening thereby directs the electrophilic attack to the face of the metalated nitrile opposite the projecting substituent. Excellent stereoselectively is maintained in a diverse range of alkylations that efficiently install quaternary centers, even with isopropyliodide in which a contiguous array of tertiary-quaternary-tertiary stereocenters is created! Screening the conformational requirements with a series of acyclic nitriles and esters reveals the key structural requirements for high selectivity while providing a robust, predictive model that accounts for comparable ester alkylations affording the opposite diastereomer! The intensive survey of metalated nitrile alkylations identifies the key structural features required for high 1,2-asymmetric induction, addresses the long-standing challenge of asymmetric alkylations with acylic metalated nitriles, and provides a versatile method for installing hindered quaternary centers with excellent stereocontrol.

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Structure and formation of [C₄H₆N]⁺ ions: 1—Ion structures derived from aliphatic nitriles

Sarneel

Heerma

Dijkstra

1981

Org. Mass Spectrom.

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α-Bromination of primary nitriles

Cited by 10 publications

References 3 publications

Influence of the Axial Alkyl Ligand on the Reduction Potential of Alkylcob(III)alamins and Alkylcob(III)yrinates

Influence of the Axial Alkyl Ligand on the Reduction Potential of Alkylcob(III)alamins and Alkylcob(III)yrinates

Metalated Nitriles: Internal 1,2-Asymmetric Induction

Structure and formation of [C₄H₆N]⁺ ions: 1—Ion structures derived from aliphatic nitriles

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α-Bromination of primary nitriles

Cited by 10 publications

References 3 publications

Influence of the Axial Alkyl Ligand on the Reduction Potential of Alkylcob(III)alamins and Alkylcob(III)yrinates

Influence of the Axial Alkyl Ligand on the Reduction Potential of Alkylcob(III)alamins and Alkylcob(III)yrinates

Metalated Nitriles: Internal 1,2-Asymmetric Induction

Structure and formation of [C4H6N]+ ions: 1—Ion structures derived from aliphatic nitriles

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Structure and formation of [C₄H₆N]⁺ ions: 1—Ion structures derived from aliphatic nitriles