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Elimination Sequence (elimination + sequence)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Stereoselective Preparation of Dienyl Zirconocene Complexes via a Tandem Allylic C,H Bond Activation,Elimination Sequence.

CHEMINFORM, Issue 10 2004
Nicka Chinkov
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

New Approach to the Stereoselective Synthesis of Metalated Dienes via an Isomerization,Elimination Sequence.

CHEMINFORM, Issue 1 2003
Nicka Chinkov
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Rapid and Easy Access to (E)-1,3-Enynes, 1,3-Diynes and Allenes Starting from Propargylic Acetals, Exploiting the Different Reactivity of Lithium and Mixed Lithium,Potassium Organometallic Reagents

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 35 2007
Marco Blangetti
Abstract The treatment of propargylic acetals with various lithium and mixed lithium,potassium Schlosser reagents, has allowed a one-pot synthesis of (E)-1,3-enynes, 1,3-diynes and allenes, depending on the reaction conditions and the selected base. Various reaction conditions were investigated in order to control the selectivity of the reactions and to obtain pure products. The metallation,elimination sequence in the presence of a suitable electrophile has provided a linear route to functionalized (E)-conjugated enynes, diynes and allenes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Synthesis and Structure of a 2,4-Unsubstituted cis/trans -1,3-Disilacyclobutane by Dehydrofluorination of a Highly Hindered Fluorosilane

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2005
Rudolf Pietschnig
Abstract The preparation, molecular structure, and metalation behavior of a sterically highly congested fluorosilane (tBuTipMeSiF) are described. This silane is subjected to dehydrofluorination under thermally mild conditions. A C -unsubstituted transient intermediate , either the silene or the corresponding silenoid , is generated in a metalation/elimination sequence at low temperatures, and this intermediate dimerizes to give the corresponding 1,3-disilacyclobutane exclusively, even in the presence of a trapping agent. The significant steric hindrance in the starting fluorosilane and the final 1,3-disilacyclobutane is corroborated by their crystal structures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Diastereo- and Enantioselective Intramolecular [2+2],Photocycloaddition Reactions of 3-(,,-Alkenyl)- and 3-(,,-Alkenyloxy)-Substituted 5,6-Dihydro-1H -pyridin-2-ones

CHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2010
Dominik Albrecht Dr.
Abstract 3-(,,-Alkenyl)-substituted 5,6-dihydro-1H -pyridin-2-ones 2,4 were prepared as photocycloaddition precursors either by cross-coupling from 3-iodo-5,6-dihydro-1H -pyridin-2-one (8) or,more favorably,from the corresponding ,-(,,-alkenyl)-substituted ,-valerolactams 9,11 by a selenylation/elimination sequence (56,62,% overall yield). 3-(,,-Alkenyloxy)-substituted 5,6-dihydro-1H -pyridin-2-ones 5 and 6 were accessible in 43 and 37,% overall yield from 3-diazopiperidin-2-one (15) by an ,,,-chloroselenylation reaction at the 3-position followed by nucleophilic displacement of a chloride ion with an ,-alkenolate and oxidative elimination of selenoxide. Upon irradiation at ,=254,nm, the precursor compounds underwent a clean intramolecular [2+2] photocycloaddition reaction. Substrates 2 and 5, tethered by a two-atom chain, exclusively delivered the respective crossed products 19 and 20, and substrates 3, 5, and 6, tethered by longer chains, gave the straight products 21,23. The completely regio- and diastereoselective photocycloaddition reactions proceeded in 63,83,% yield. Irradiation in the presence of the chiral templates (,)- 1 and (+)- 31 at ,75,°C in toluene rendered the reactions enantioselective with selectivities varying between 40 and 85,%,ee. Truncated template rac - 31 was prepared as a noranalogue of the well-established template 1 in eight steps and 56,% yield from the Kemp triacid (24). Subsequent resolution delivered the enantiomerically pure templates (,)- 31 and (+)- 31. The outcome of the reactions is compared to the results achieved with 4-substituted 5,6-dihydro-1H -pyridin-2-ones and quinolones. [source]