38661-86-8Relevant articles and documents
Nazarov cyclization of divinyl ketones bearing an ester group at the β-position: A remarkable effect of α-substitution and alkene geometry on regioselectivity
Sudhakar, Gangarajula,Raghavaiah, Jakka,Mahesh, Gaddam,Singarapu, Kiran Kumar
, p. 2866 - 2872 (2016/03/12)
The Nazarov cyclization of divinyl ketones with an ester at the β-position was examined with particular reference to where the cyclic double bond forms. We observed unprecedented regioselectivity, dictated by the subtle substitution patterns at the α-position and alkene geometry of α,β and mostly, this selectivity is regardless of substitutions at α′- and β′-positions. The major implications of these observations are an aromatic group at the α-position with E-olefin geometry provides a cyclopentenone in which the double bond is not in conjugation with an ester, whereas Z-olefin provides a cyclopentenone in which the double bond is in conjugation with an ester; and divinyl ketones bearing an ester group at the β-position and an alkyl group at the α-position with E-olefin geometry provide a cyclopentenone in which the double bond is in conjugation with the ester.
A stereoselective and practical synthesis of (E)-α,β-unsaturated ketones from aldehydes
Balducci, Evita,Attolino, Emanuele,Taddei, Maurizio
experimental part, p. 311 - 318 (2011/02/28)
α,β-Unsaturated ketones can be prepared by reaction of differently substituted β-keto acids and aldehydes. The reaction is carried out under organocatalysis (β-alanine, 0.5 equiv.) and generates the enones with high E selectivity (>95%). This version of the Verley-Doebner modification of the Knoevenagel reaction is a practical alternative to the classic Horner-Wadsworth-Emmons (HWE) reaction without the formation of high molecular weight byproducts. The process makes use of simple reagents and can be applied to large-scale synthesis under conditions compatible with atom-economy principles. Differently substituted aliphatic, aromatic, or heteroaromatic α,β-unsaturated ketones can be prepared. An example of a hydroformylation/Verley-Doebner Knoevenagel telescoped process is also described. The conditions used in the Knoevenagel reaction to prepare conjugated esters under amino acid organocatalysis can be applied also for the synthesis of α,β unsaturatedketones. β-Keto acids are prepared byhydrogenolysis of the corresponding benzyl ester and react easily with aldehydes to give the α,β-unsaturated ketones without formation of high molecular weight byproducts. Copyright
Formation and Reactions of 1-Phenyl-2-propanone Dianion and Related Systems with Electrophilic Reagents
Trimitsis, G. B.,Hinkley, J. M.,TenBrink, R.,Faburada, A. L.,Anderson, R.,et al.
, p. 2957 - 2962 (2007/10/02)
1-Phenyl-2-propanone, 1,1-diphenyl-2-propanone, and 1-(4-methoxyphenyl)-2-propanone were converted to their dicarbanions 3, 4, and 31, respectively, and their reactions with a number of electrophilic reagents were examined.All three dianions gave a mixture of C-1 and C-3 alkylation products when treated with alkyl halides of higher reactivity, while only C-1 alkylations occurred when alkyl halides of lower reactivity were used.It was also found that the 1,1-diphenyl-2-propanone and the 1-(4-methoxyphenyl)-2-propanone dianions 4 and 31 gave a higher ratio of C-1/C-3 alkylation products than the 1-phenyl-2-propanone dianion 3.When dianion 3 was reacted with p-anisaldehyde and a number of protonating agents, electrophilic attack occurred exclusively at the C-3 position.The trends observed are analyzed, and mechanisms are proposed to account for the results obtained.
