20561-10-8Relevant academic research and scientific papers
Formal diels-alder reactions of chalcones and formylcyclopropanes catalyzed by chiral n-heterocyclic carbenes
Lv, Hui,Mo, Junming,Fang, Xinqiang,Chi, Yonggui Robin
supporting information; experimental part, p. 5366 - 5369 (2011/12/03)
Highly enantioselective (formal) hetero-Diels-Alder reactions between chalcones and formylcyclopropanes are disclosed. The challenging N-heterocyclic carbene (NHC)-bounded enolate intermediates from formylcyclopropanes were captured for new C-C bond formi
N-Heterocyclic carbene catalyzed ring expansion of formylcyclopropanes: Synthesis of 3,4-dihydro-α-pyrone derivatives
Li,Dai,You
supporting information; experimental part, p. 1623 - 1625 (2009/09/06)
N-Heterocyclic carbene catalyzed ring expansion of readily accessible 2-acyl-1-formylcyclopropanes was developed. With 5 mol % of triazolium salt 5 and 30 mol % of DBU, ring expansion of various 2-acyl-1-formylcyclopropanes led to 3,4-dihydro-α-pyrones in
The direct preparation of functionalised cyclopropanes from allylic alcohols or α-hydroxyketones using tandem oxidation processes
McAllister, Graeme D.,Oswald, Magalie F.,Paxton, Richard J.,Raw, Steven A.,Taylor, Richard J.K.
, p. 6681 - 6694 (2007/10/03)
New manganese dioxide-mediated tandem oxidation processes (TOPs) have been developed, which facilitate the direct conversion of allylic alcohols and α-hydroxyketones into polysubstituted functionalised cyclopropanes. In the simplest version, the oxidation of an allylic alcohol is carried out in the presence of a stabilised sulfurane, and the intermediate α,β-unsaturated carbonyl compound undergoes in situ cyclopropanation. By using a combination of stabilised phosphorane and sulfurane, the direct conversion of allylic alcohols or α-hydroxyketones into functionalised cyclopropanes is achieved, with in situ cyclopropanation being followed by Wittig olefination, or vice versa. The application of these methods to a formal synthesis of the lignan (±)-picropodophyllone, and to novel analogues of the insecticide allethrin II, is described.
Tandem oxidation processes for the preparation of functionalized cyclopropanes
Oswald, Magalie F.,Raw, Steven A.,Taylor, Richard J. K.
, p. 3997 - 4000 (2007/10/03)
(Chemical Equation Presented) A novel manganese dioxide-mediated tandem oxidation process (TOP) has been developed which allows the direct conversion of allylic alcohols into cyclopropanes, the intermediate aldehydes being trapped in situ with a stabilized sulfur-ylide. This methodology has been applied successfully to a variety of allylic alcohols and to a formal synthesis of the simple, naturally occurring lignan, (±)-picropodophyllone.
Organic-catalyst-mediated cyclopropanation reaction
Papageorgiou, Charles D.,Ley, Steven V.,Gaunt, Matthew J.
, p. 828 - 831 (2007/10/03)
A catalytic ammonium ylide based cyclopropanation process forms trans-disubstituted cyclopropanes in good yield upon reaction with electron-deficient alkenes (see scheme; EWG = electron-withdrawing group). The reaction is also highly enantioselective when
Thermal Ring-Expansion of N-Acyl Cyclopropyl Imines
Wu, Pei-Lin,Wang, Wen-Shan
, p. 622 - 627 (2007/10/02)
The FVT of N-acyl cyclopropyl imines with methyl, phenyl, and acyl substituents at C-1 or C-2 of the cyclopropyl ring has been studied.The parent N-acyl cyclopropyl imine and N-acyl methylcyclopropyl imines gave no ring-expansion products but ring-opened mixtures, decomposed fragments, and polymerization tars after FVT, whereas N-acyl phenylcyclopropyl imines and N-acyl acylcyclopropyl imines generated ring-expansion products, 2-pyrrolines.It demonstrates the first study on the thermal rearrangement of N-acyl cyclopropyl imines.
