4168-01-8Relevant articles and documents
Die Acylierung von Acetylenen mit β,γ-ungesaettigten Saeurechloriden. Eine neue Synthese von 5-substituierten 2-Cyclopentenonen
Karpf, Martin
, p. 73 - 85 (1984)
The acylation of acetylenes with α,α-disubstituted, β,γ-unsaturated acid chlorides under Friedel-Crafts-type conditions leads to 5-substituted 2-cyclopentenones.Phenols are formed with β,γ-unsaturated acid chlorides bearing at least one α-H-atom.These transformations are explained by the intramolecular cyclization of the initially formed vinyl cation, which, in the cases of α,α-disubstituted acid chlorides, is formed by ring contraction.The reaction leading to 2-cyclopentenones is applied to the syntesis of some spirodeca-2,6-dienones.
A Light/Ketone/Copper System for Carboxylation of Allylic C-H Bonds of Alkenes with CO2
Ishida, Naoki,Masuda, Yusuke,Uemoto, Sho,Murakami, Masahiro
supporting information, p. 6524 - 6527 (2016/05/02)
A photo-induced carboxylation reaction of allylic C-H bonds of simple alkenes with CO2 is prompted by means of a ketone and a copper complex. The unique carboxylation reaction proceeds through a sequence of an endergonic photoreaction of ketones with alkenes forming homoallyl alcohol intermediates and a thermal copper-catalyzed allyl transfer reaction from the homoallyl alcohols to CO2 through C-C bond cleavage. An allylic C-H bond of simple alkenes is carboxylated with CO2 in the presence of a substoichiometric amount of a ketone and a catalytic amount of a copper complex under UV irradiation (see scheme).
Metal-free oxyaminations of alkenes using hydroxamic acids
Schmidt, Valerie A.,Alexanian, Erik J.
, p. 11402 - 11405 (2011/09/16)
A radical-mediated approach to metal-free alkene oxyamination is described. This method capitalizes on the unique reactivity of the amidoxyl radical in alkene additions to furnish a general difunctionalization using simple diisopropyl azodicarboxylate (DIAD) as a radical trap. This protocol capitalizes on the intramolecular nature of the process, providing single regioisomers in all cases. Difunctionalizations of cyclic alkenes provide trans oxyamination products inaccessible using current methods with high levels of stereoselectivity, complementing cis-selective oxyamination processes.
Restricted stereochemistry of solvation of allylic lithium compounds: Structural and dynamic consequences
Fraenkel, Gideon,Duncan, Joseph H.,Wang, Jinhai
, p. 432 - 443 (2007/10/03)
Several 1-sila allylic lithium compounds have been prepared with potential ligands for Li substituted at the 2-position. They are [2-[[cis-2,5-bis(methoxymethyl)-1-pyrrolidinyl]methyl]-1-(trimethylsilyl)allyl] lithium (22), [2-[[cis-2,5-bis(methoxymethyl)-1-pyrrolidinyl]methyl]-1-(dimethylethylsilyl) allyl]lithium(23), [2-[[bis-(2-methoxyethyl)amino]methyl]-1-(dimethylethylsilyl)allyl]lithium (24), [2-[[bis(2-methoxyethyl)amino]methyl]-1-(tert-butyldimethylsilyl)allyl]lithium (25), and [2-[2-[bis(2-methoxyethyl)amino]-1,1-dimethylethyl](ethyl-dimethylsilyl)] allyllithium (26). Using diethyl ether or THF solutions all these compounds exhibited one bond 13C, 7Li spin coupling of ～8 Hz, a 1:1:1:1 13C NMR pattern indicating monomeric structures; all show ligand resonances to be magnetically nonequivalent and reveal C1, C3 13C NMR shifts of about 40 and 75 δ which lie between those for model delocalized 1 and localized species 2. These compounds are concluded to be examples of the heretofore missing folded, internally tridentately coordinated partially delocalized structures with small detectable C, Li covalence. The exception is 25 which, in diethyl ether, consists of a rapidly interconverting equilibrium mixture of localized and delocalized more solvated forms, the former prevailing at 300 K and progressively converting mainly to the latter by 180 K. NMR line shape analysis of the diastereotopic gem methylsilyl 13C resonances as well as that due to the ligand carbons shows that all these line shape changes are due to the dynamics of inversion at lithium-bound carbon and that other ligand reorientation processes are slower than carbanide inversion; for inversion, ΔH? is found to be 6-9 kcal?mol-1, respectively. Averaging with increasing temperature of the 13C, 7Li spin coupling in 24 provides the dynamics of bimolecular carbon lithium bond exchange with ΔH? of 12 kcal?mol-1. Mechanisms are proposed on the basis of the data. We ascribe restricted stereochemistry of ligand lithium coordination to be responsible for these unusual internally coordinated structures.
