منابع مشابه
Orbital Energy Control of Cycloaddition Reactivity
A reactivity model for concerted cycloaddition reactions is presented which allows a systematization of substituent effects. The treatment is based on the frontier electron theory of Fukui. The consideration of the energy separations of HOMOs (Highest Occupied Molecular Orbitals) and LUMOs (Lowest Unoccupied Molecular Orbitals) leads to three reactivity types in these cycloadditions. For the Di...
متن کاملEnhancing the reactivity of 1,2-diphospholes in cycloaddition reactions
Two different approaches have been employed to enhance the reactivity of 1-alkyl-1,2-diphospholes - the introduction of electron-withdrawing groups either at the phosphorus atoms or in the para-position of the arene ring. The alkylation of sodium 1,2-diphospha-3,4,5-triphenylcyclopentadienide with alkyl halides Hal-CH2-R (R = CN, COOEt, OMe, CH2OEt) results in corresponding 1-alkyl-3,4,5-triphe...
متن کاملChemical reactivity of dihydropyrazine derivatives. Cycloaddition behavior toward ketenes.
The cycloaddition behavior of dihydropyrazines toward ketenes was investigated using single-crystal X-ray structures of the cycloadducts and density functional theory (DFT) calculation data. The reaction proceeds via a stepwise pathway involving an orientation complex prior to formation of the betaine intermediate. This is followed by electrocyclization to afford the 1 : 1 and 1 : 2 adducts bea...
متن کاملRearrangement from the heteroantiaromatic borole to the heteroaromatic azaborine motif.
Treatment of 9-chloro-9-borafluorene with N,O-bis(trimethylsilyl)hydroxylamine results in 10-trimethylsilyloxy-9-aza-10-boraphenanthrene 6b. NMR spectroscopy shows that the expected antiaromatic 9-(trimethylsilyloxyamino)-9-borafluorene 5b rearranges to the formally aromatic phenanthrene 6b at room temperature.
متن کاملPhotocycloaddition of aromatic and aliphatic aldehydes to isoxazoles: Cycloaddition reactivity and stability studies
The first photocycloadditions of aromatic and aliphatic aldehydes to methylated isoxazoles are reported. The reactions lead solely to the exo-adducts with high regio- and diastereoselectivities. Ring methylation of the isoxazole substrates is crucial for high conversions and product stability. The 6-arylated bicyclic oxetanes 9a-9c were characterized by X-ray structure analyses and showed the h...
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ژورنال
عنوان ژورنال: Chemistry – A European Journal
سال: 2021
ISSN: 0947-6539,1521-3765
DOI: 10.1002/chem.202101290