Design and Synthesis of Novel <i>C</i><sub>2</sub>-Symmetric Chiral Piperazines and an Application to Asymmetric Acylation of σ-Symmetric 1,2-Diols

Nakamura, Daisuke; Kakiuchi, Kiyomi; Koga, and Kenji; Shirai, Ryuichi

doi:10.1021/ol0626387

Cited by 82 publications

(29 citation statements)

References 26 publications

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“…CycloA C H T U N G T R E N N U N G (Pro,Pro) (11) was prepared from the commercial HCl salt of l-proline in the presence of NaHCO 3 in 50% yield. [18] As expected, we found that cycloA C H T U N G T R E N N U N G (Pro,Pro) (11) when in contact with triplet oxygen in DMF did not give rise to the corresponding peroxide 12 (Table 1). The peroxidation of such deriv- …”

Section: Resultssupporting

confidence: 78%

Pyrrole‐Assisted and Easy Oxidation of Cyclic α‐Amino Acid‐ Derived Diketopiperazines under Mild Conditions

et al. 2011

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A new procedure for the aerobic oxidation of a-amino acids acylated by pyrrole-carboxylic acid with triplet dioxygen is introduced. The reaction is general for a variety of pyrrole-amino acid derivatives and represents a very practical and controllable method for the selective preparation of a-hydroperoxy-or a-hydroxy-a-amino acid diketopiperazines with molecular dioxygen. Furthermore, the non-catalyzed direct oxidation of amino acid derivatives at the a-position with molecular dioxygen represents a fundamental question.

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Section: Resultssupporting

confidence: 78%

Pyrrole‐Assisted and Easy Oxidation of Cyclic α‐Amino Acid‐ Derived Diketopiperazines under Mild Conditions

et al. 2011

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“…A new C 2 -symmetric quaternary ammonium salt 2 was conveniently prepared by simple dialkylation of a known diamine 1, which was synthesized from L-proline according to literature procedure [24] (Scheme 1). To investigate the feasibility of this C 2 -symmetric quaternary ammonium salt applying to phase-transfer catalysis, we carried out Michael addition reactions of various active methylene compounds to aromatic a, b-unsaturated ketones under PTC conditions.…”

Section: Resultsmentioning

confidence: 99%

Phase-Transfer Catalyzed Michael Addition Reaction Using a New C2-Symmetric Quaternary Ammonium Salt Derived From l-Proline

Xie

Zhang

2011

Catal Lett

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A new C 2 -symmetric quaternary ammonium salt easily prepared from L-proline, was developed and used as an efficient phase-transfer catalyst (PTC) in Michael addition reaction of various active methylene compounds to aromatic enones. Malonate esters and acetylacetone were reacted smoothly with various a, b-unsaturated ketones in good to excellent yields, the reaction conditions were optimized and the substrate scope was also investigated. Thereby, a practical Michael addition methodology was established under phase-transfer catalytic conditions with many advantages, including easy availability of catalyst, mild reaction conditions, short reaction times, simple workup procedures.

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“…Multiplying Eqns (7), (8), (9), (10), and (11) by a factor of 10 and Eqns (12), (13), (14), and (15) by a factor of five and Eqn (16) by a factor of two, and then summing them with each other results in the overall reaction with the stiochiometry satisfied. In agreement with the above scheme, assuming a steady state approximation for X þ 1 , the rate equation obtained for the uncatalysed process is…”

Section: Hmno 4 ð7þmentioning

confidence: 99%

Kinetics and Mechanism of the Kmn0₄-Oxidative Catalysed Condensation Reaction of L-Proline to a Diketopiperazine: Evidence for Delayed Autocatalytic Behaviour

Davari

Bahrami

Zahedi

et al. 2011

Progress in Reaction Kinetics and Mechanism

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The kinetics and mechanism of the KMnO 4 -oxidative catalysed condensation reaction of L-proline, as a cyclic secondary amino acid, has been investigated spectrophotometrically. Product analysis has revealed, that in contrast to the usual reaction of a-amino acids, which results in an aldehyde species, a valuable diketopiperazine, namely cyclo(L-pro-L-pro), is obtained as the main product, providing a cheap, simple, efficient, and novel method. Conclusive evidence has demonstrated delayed autocatalytic activity involving Mn 2 þ in this reaction, analogous to that shown by chain primary a-amino acids. It has been revealed that such activity can emerge when a certain concentration of Mn 2 þ is built up in the medium, to which we refer as the ''critical concentration''. Moreover, the ''critical concentration'' for the appearance of ''autocatalytic behaviour'' in this oxidative process is affected by the nature of the amino acid used, as reported in previous studies, while the magnitude of the critical concentration depends on the sulfuric acid concentration. In considering ''delayed autocatalytic behaviour'' of Mn 2 þ ions, rate equations satisfying experimental data for both catalytic and noncatalytic routes have been presented. The reaction shows a first-order dependence on permanganate ion concentration, both in the catalytic and non-catalytic pathways, and an apparent first-order dependence on Mn 2 þ ions in the catalytic pathway. The correspondence of the pseudo-order rate constants of the catalytic and non-catalytic pathways to the Arrhenius and Eyring laws verified both the ''critical concentration'' and ''delayed autocatalytic behaviour'' concepts. The activation parameters associated with the reaction pseudo-rate constants k 1 0 and k 2 0 are computed and discussed. Proposed mechanisms for both catalytic and noncatalytic routes include a diacyclperoxide intermediate, which leads to a C 2symmetric chiral product having a diketopiperazine skeleton.

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Design and Synthesis of Novel C₂-Symmetric Chiral Piperazines and an Application to Asymmetric Acylation of σ-Symmetric 1,2-Diols

Cited by 82 publications

References 26 publications

Pyrrole‐Assisted and Easy Oxidation of Cyclic α‐Amino Acid‐ Derived Diketopiperazines under Mild Conditions

Pyrrole‐Assisted and Easy Oxidation of Cyclic α‐Amino Acid‐ Derived Diketopiperazines under Mild Conditions

Phase-Transfer Catalyzed Michael Addition Reaction Using a New C2-Symmetric Quaternary Ammonium Salt Derived From l-Proline

Kinetics and Mechanism of the Kmn0₄-Oxidative Catalysed Condensation Reaction of L-Proline to a Diketopiperazine: Evidence for Delayed Autocatalytic Behaviour

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Design and Synthesis of Novel C2-Symmetric Chiral Piperazines and an Application to Asymmetric Acylation of σ-Symmetric 1,2-Diols

Cited by 82 publications

References 26 publications

Pyrrole‐Assisted and Easy Oxidation of Cyclic α‐Amino Acid‐ Derived Diketopiperazines under Mild Conditions

Pyrrole‐Assisted and Easy Oxidation of Cyclic α‐Amino Acid‐ Derived Diketopiperazines under Mild Conditions

Phase-Transfer Catalyzed Michael Addition Reaction Using a New C2-Symmetric Quaternary Ammonium Salt Derived From l-Proline

Kinetics and Mechanism of the Kmn04-Oxidative Catalysed Condensation Reaction of L-Proline to a Diketopiperazine: Evidence for Delayed Autocatalytic Behaviour

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Design and Synthesis of Novel C₂-Symmetric Chiral Piperazines and an Application to Asymmetric Acylation of σ-Symmetric 1,2-Diols

Kinetics and Mechanism of the Kmn0₄-Oxidative Catalysed Condensation Reaction of L-Proline to a Diketopiperazine: Evidence for Delayed Autocatalytic Behaviour