(5aS,10aS)‐Octahydro‐1H,5H‐dipyrrolo[1,2‐a:1′,2Prime;‐d]pyrazin «DPP» als Hilfsreagenz bei der enantioselektiven 1,2‐Addition von Grignard‐Reagenzien an prochirale Carbonylverbindungen

Zadel, Guido; Breitmaier, Eberhard

doi:10.1002/cber.19941270723

Cited by 22 publications

(13 citation statements)

References 18 publications

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“…The diketopiperazines 1a, [70] 6a, [71] 16, [72] 19, [73] and 20 [74,75] have been already described as well as the diketopiperazine hydroperoxides 1b, [21a] 1c [21a] and 6b.…”

Section: Methodsmentioning

confidence: 99%

A combined quantum mechanical and experimental approach towards chiral diketopiperazine hydroperoxides

Argyrakis

Köppl

Werner

et al. 2010

J of Physical Organic Chem

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To cite this version:Sabine Laschat. A combined quantum mechanical and experimental approach towards chiral diketopiperazine hydroperoxides. Journal of Physical Organic Chemistry, Wiley, 2010, 24 (8) AbstractIn order to improve hydroperoxide formation from heterocyclic compounds relating to the formation rate and to allow a suitable choice of starting materials for autoxidation, theoretical studies on a set of different amino acid-derived diketopiperazines and pyrazinoquinazolines were carried out. To estimate their reactivity towards hydroperoxide formation, bond dissociation enthalpies (BDEs) of tertiary α-C-H bonds as well as reaction enthalpies to the corresponding hydroperoxides were calculated at the B3LYP/TZVP and RMP2/aug-cc-pVTZ level of theory. The EvansPolanyi relation was then used to correlate substrate reactivity with calculated BDEs.Thermal and zero point vibrational energy corrections were determined in the classical harmonic oscillator-rigid rotor-particle in a box model. While for the investigated set of diketopiperazines BDEs of 318.8-327.0 kJ mol -1 were found, BDEs for pyrazinoquinazolines spread between 248.4-368.4 kJ mol -1 at the B3LYP/TZVP level of theory. A selected subset of heterocycles was converted to the corresponding hydroperoxides and the diketopiperazines were obtained in up to 39 % yield after 5-7 days, whereas the pyrazinoquinazolines hydroperoxides were isolated in up to 67 % yield after 24 hours. Thus, replacing an amido moiety in an N-aryl-imino moiety when using pyrazinoquinazolines instead of diketopiperazines leads indeed to an improved captodative stabilization of the radical intermediate. Furthermore the theoretical calculations allowed a distinctive forecast of the preferred regioisomeric hydroperoxide.

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“…The diketopiperazines 1a, [70] 6a, [71] 16, [72] 19, [73] and 20 [74,75] have been already described as well as the diketopiperazine hydroperoxides 1b, [21a] 1c [21a] and 6b.…”

Section: Methodsmentioning

confidence: 99%

A combined quantum mechanical and experimental approach towards chiral diketopiperazine hydroperoxides

Argyrakis

Köppl

Werner

et al. 2010

J of Physical Organic Chem

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“…Following Breitmaier and Zadel's procedure, [8] dimerization of -proline methyl ester and then reduction of the corresponding cyclic dipeptide gave (5aS,10aS)-(+)-octahydro-1H,5H-dipyrrolo[1,2-a:1Ј,2Ј-d]pyrazine (1) (Scheme 1). Scheme 1.…”

Section: Synthesis Of Catalystsmentioning

confidence: 99%

“…Thus, the following compounds were synthesized (Scheme 5) and employed as the catalyst in combination with -proline in the coupling of o-nitrobenzaldehyde and MVK: Compound 4a with the terminal hydroxy group masked as a silyl ether (8), with both hydroxy groups protected (9), and with the secondary alcohol selectively acetylated 10. The results are listed in Table 8 Table 8.…”

Section: Preliminary Mechanistic Surveymentioning

confidence: 99%

“…[8] Iron filings (25.20 g, 450 mmol) were added to a solution of N-(2-nitrobenzoyl)--proline methyl ester (12.51 g, 45 mmol) in glacial acetic acid (200 mL) at room temperature. The reaction mixture was heated at 110°C until total consumption of the starting material (monitored by TLC, 4-6 h).…”

Section: (5as10as)-(+)-octahydro-1h5h-dipyrrolo[12-a:1ј2ј-d]pyrazmentioning

confidence: 99%

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Chiral Tertiary Amine/L‐Proline Cocatalyzed Enantioselective Morita–Baylis–Hillman (MBH) Reaction

et al. 2007

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Four types of chiral amines have been synthesized starting from readily available chiral sources. These chiral amines in combination with L-proline have been found to be efficient cocatalysts for the asymmetric Morita-Baylis-Hillman (MBH) reaction between methyl vinyl ketone (MVK) and aromatic aldehydes. The corresponding adducts were formed in reasonable chemical yields and with good enantioselectivities (up to 83 % ee). Moreover, parallel cocatalytic reactions with the two enantiomers of chiral amine 4 and L-proline revealed

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“…thermal cycloamidation [23] or vaporous condensation [24] of sublimated amino acids under reduced pressure in the presence of silica. The yields of diketopiperazines prepared in this manner are comparable, but the substrate scope is limited to the thermal stability of the used α-amino acids and the stereoselectivity is not consistent.…”

Section: Introductionmentioning

confidence: 99%

Microwave‐Assisted Stereoselective One‐Pot Synthesis of Symmetrical and Unsymmetrical 2,5‐Diketopiperazines from Unprotected Amino Acids

2008

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The facile condensation of unprotected amino acids by a phosphite‐promoted one‐step coupling reaction is a highly efficient synthesis to generate stereoselective and optically pure symmetrical and unsymmetrical functionalized diketopiperazines. The use of microwaves enhanced by small amounts of ionic liquid is accompanied by significant improvement in reaction times and yields. Simple filtration through a pad of silica provides the pure compounds in very good to excellent yields.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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(5aS,10aS)‐Octahydro‐1H,5H‐dipyrrolo[1,2‐a:1′,2Prime;‐d]pyrazin «DPP» als Hilfsreagenz bei der enantioselektiven 1,2‐Addition von Grignard‐Reagenzien an prochirale Carbonylverbindungen

Cited by 22 publications

References 18 publications

A combined quantum mechanical and experimental approach towards chiral diketopiperazine hydroperoxides

A combined quantum mechanical and experimental approach towards chiral diketopiperazine hydroperoxides

Chiral Tertiary Amine/L‐Proline Cocatalyzed Enantioselective Morita–Baylis–Hillman (MBH) Reaction

Microwave‐Assisted Stereoselective One‐Pot Synthesis of Symmetrical and Unsymmetrical 2,5‐Diketopiperazines from Unprotected Amino Acids

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