Probing the "additive effect" in the proline and proline hydroxamic acid catalyzed asymmetric addition of nitroalkanes to cyclic enones

Probing the "additive effect" in the proline and proline hydroxamic acid catalyzed asymmetric addition of nitroalkanes to cyclic enones

The effect of chirality and steric bulk of 2,5‐disubstituted piperazines as additives in the conjugate addition of 2‐nitropropane to cyclohexenone, catalyzed by l‐proline, was investigated. Neither chirality nor steric bulk affects the enantioselectivity of addition, which gives 86–93% ee in the pre...

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Veröffentlicht in:Chirality (New York, N.Y.) N.Y.), 2005, Vol.17 (9), p.540-543
Hauptverfasser: Hanessian, Stephen, Govindan, Subramaniyan, Warrier, Jayakumar S.
Format: Artikel
Sprache:eng
Schlagworte:
Alkanes - chemistry
Catalysis
conjugate addition
Cyclization
Hydroxamic Acids - chemistry
Molecular Structure
Nitro Compounds - chemistry
organocatalysis
piperazine
proline
Proline - chemistry
proline hydroxamic acid
Stereoisomerism
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Zusammenfassung:The effect of chirality and steric bulk of 2,5‐disubstituted piperazines as additives in the conjugate addition of 2‐nitropropane to cyclohexenone, catalyzed by l‐proline, was investigated. Neither chirality nor steric bulk affects the enantioselectivity of addition, which gives 86–93% ee in the presence of achiral and chiral nonracemic 2,5‐disubstituted piperazines. Proline hydroxamic acid is shown for the first time to be an effective organocatalyst in the same Michael reaction. © 2005 Wiley‐Liss, Inc. Chirality 17:540–543, 2005.
ISSN:0899-0042
1520-636X
DOI:10.1002/chir.20201