No abstract

No abstract

A simple, efficient and low-cost methodology for the synthesis of α-aryl-α,βunsaturated esters using paraformaldehyde as a source of carbon was developed. Factors that control reaction yields such as temperature, concentration and reaction time were evaluated. A mechanism is proposed based on experimental structures of the intermediates.

The chemical shifts of protons depend not only on the properties of the solute molecule but also on the medium in which the solute resides. A series of β-lactams with various substitution patterns were synthesized to study aromatic-solvent-induced shifts (ASISs) in chloroform and benzene by using 1H NMR spectroscopy. The results agreed with those obtained by theoretical density functional theory calculations. The protons of the β-lactam ring are the most affected by the ASIS effect, and they tend to overlap due to the anisotropic effect of benzene.

Recent progress of the catalytic promiscuity of enzymes have invigorated the use of biocatalysis in organic chemistry. Explorations of biocatalysis for the synthesis of esters are critical since up to now, existing traditional methods are complicated, which usually require long reaction times, microwaves or even toxic reagents. This paper presents a versatile biocatalytic methodology to obtain benzyl esters through a transesterification reaction of methyl esters with Candida antarctica lipase B (CaLB) and benzyl alcohol in the absence of solvent. In addition, the effect of the nucleophile size and the substituent directly attached to the carbonyl group was studied. The results show that, in some cases, using a vacuum shifts the equilibrium of the reaction towards the products. Based on these results, molecular docking studies were carried out, where specific regions in the CaLB catalytic cavity were analyzed.