70090-81-2Relevant academic research and scientific papers
Gold(I)-catalyzed rearrangement of propargyl benzyl ethers: A practical method for the generation and in situ transformation of substituted allenes
Bolte, Benoit,Odabachian, Yann,Gagosz, Fabien
supporting information; experimental part, p. 7294 - 7296 (2010/08/05)
A series of benzyl propargyl ethers react with a gold(I) catalyst to furnish variously substituted allenes via a 1,5-hydride shift/fragmentation sequence. This transformation is rapid and practical. It can be performed under very mild conditions (room temperature or 60 °C) using terminal as well as substituted alkyne substrates bearing a primary, secondary, or tertiary benzyl ether group. The allenes thus formed can be reacted in situ with an internal or external nucleophile, corresponding to an overall reductive substitution process, to produce more functionalized compounds.
Photochemical and Thermal Hydrations of Aromatic Allenes. Evidence for Allyl and Vinyl Cation Intermediates
Rafizadeh, Karim,Yates, Keith
, p. 1500 - 1506 (2007/10/02)
The photohydration of aromatic allenes has been studied in water and in dilute aqueous sulfuric acid (0-25percent H2SO4).It was found that phenylallene (2a) and α-methylphenylallene (2b) undergo photohydration to give the corresponding cinnamyl alcohol derivatives.The proposed mechanism involves protonation of the central carbon of phenylallenes in their singlet excited state (S1).In contrast, (p-nitrophenyl)allene (2g) and (m-nitrophenyl)allene (2h) gave the corresponding (nitrophenyl)acetones.The mechanism for the formation of these ketones is believed to be due to initial protonation of the α- or γ-carbon atom of the (nitrophenyl)allene in the triplet excited state (T1).Phenylallenes with CN, CF3, and F substituents failed to photohydrate.The results of these photohydrations were compared with those of the much slower thermal hydrations in 70-83percent H2SO4.Phenylallenes 2a and 2b cyclized to the corresponding indene derivatives in 70percent H2SO4.Phenylallenes with NO2-substituents (2g-2h) underwent hydration to give the corresponding (nitrophenyl)acetones (expected products) and (nitrophenyl)-1-propanones (unexpected products) in 83percent H2SO4.Similar results were obtained with (m-cyanophenyl)allene.The formation of both types of ketone is discussed in terms of the intermediacy of a common vinyl cation intermediate.
