65220-55-5

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• 53940-12-8 (E)-3-phenyl-1-(pyridin-2-yl)-2-propen-1-one 

Relevant academic research and scientific papers

AlCl3-Promoted Conjugate Reduction of α,β-Unsaturated Carbonyl Compounds with 1,3-Dimethyl-2-phenylbenzimidazoline

The reduction of a variety of α,β-unsaturated carbonyl compounds, except for α,β-unsaturated aldehyde, to the corresponding saturated carbonyl compounds was effectively performed by using 1,3-dimethyl-2-phenylbenzimidazoline (DMBI) as a reducing agent with the aid of AlCl3.The reduction is discussed on the basis of the hydride-donating ability of DMBI, together with the role of AlCl3 as an electrophilic activator for the substrates.The catalytic efficiency of Lewis acids was found to be proportional to the efficiency to form a complex with a carbonyl group.The reduction of 2-cinnamoylpyridine with 2-deuterated DMBI revealed that in the reduction product, a deuterium atom was located at the β-position with respect to the carbonyl group.On the other hand, the reduction of the same substrate with DMBI followed by quenching with D2O gave a reduced product which contained a deuterium label at the α-position.These results were interpreted in terms of a mechanism involving an enolate intermediate produced by either a one-step hydride transfer or a sequential transfer of an electron (e) and a hydrogen atom (H.) from the reducing agent to the substrate.

Lewis Acid-prompted Conjugate Reduction of α,β-Unsaturated Carbonyl Compounds by 2-Phenylbenzothiazoline (2-Phenyl-2,3-dihydrobenzothiazole)

Reduction of various α,β-unsaturated ketones (3a-g) and (4a-d) in methanol by the benzothiazoline (1) in the presence of aluminium chloride gives, in all cases, the corresponding saturated ketones (5a-g) and (6a-d)without any of the unsaturated or saturated alcohol.Reduction of α,β-unsaturated esters (7a,b) similarly gives the saturated esters (9a,b), while reaction of cinnamaldehyde (8) with compound (1) does not occur at all.Among the Lewis acids examined, aluminium chloride gives the best results.Reduction of 2'-azachalcone (21) with 2-phenylbenzothiazoline reveals that, in the reduction product, the deuterium atom is located at the β-position with respect to the carbonyl group.The result obtained from the reduction of the same substrate with compound (1) in methanol shows that no incorporation of a hydrogen atom from the solvent takes place and suggests (indirectly) that the introduced hydrogen atom at the α-position of the product comes from the benzothiazoline (1).The reaction of (Z)-1,2-dibenzoyl-1,2-diphenylethylene (30) with compound (1) in the presence of aluminium chloride stereospecifically yields meso-1,2-dibenzoyl-1,2-diphenylethane (31).This shows that the transfer of two hydrogens from compound (1) to the carbon-carbon double bond of the enone proceeds via cis-addition.Experiments with ethyl phenylpropiolate (28) also support cis-reduction for the present conjugate reduction.These results are interpreted in terms of a mechanism involving synchronous transport of a pair of hydrogens from the benzothiazoline (1); i.e a cyclic addition of the two hydrogens either in exact or nearly exact concurrence.