During a study of the regioselectivity of the Suzuki coupling of dihalopyrrole esters, the first instance of a reversal of regioselectivity based upon a change in reaction solvent has been observed. It is believed that this change in regioselectivity is due to a change in solvation of the pyrrole ester, since a change in chemical shift values is observed for the C3 and C5 protons upon going fro...

Triazolinylidenes promote γ-selective C-carboxylation (up to 99 : 1 regioselectivity) in the O- to C-carboxyl transfer of furanyl carbonates in contrast to DMAP that promotes preferential α-C-carboxylation with moderate regiocontrol (typically 60 : 40 regioselectivity). The generality of this process is described and a simple mechanistic and kinetic model postulated to account for the observed ...

The regioselective ring opening of styrene oxide using elemental iodine and bromine in the presence of disulfides as new catalysts was studied. The conductivity titration and UV spectroscopy were used to study the interaction of iodine with these catalysts. The results indicate that disulfide 11 is efficient in polyiodide formation, and can catalyze this reaction in excellent yield and high reg...

N-Ethylmaleimide and maleic anhydride add to the interior face of one anthracene wall with unusual 1,4-regioselectivity, whereas singlet oxygen adds to both anthracene walls with 9,10-regioselectivity.

Conventional frontier molecular orbital theory is not able to satisfactorily explain the regioselectivity outcome of the nitrilimine-alkene cycloaddition. We considered that conceptual density functional theory (DFT) could be an effective theoretical framework to rationalize the regioselectivity of the title reaction. Several nitrilimine-alkene cycloadditions were analyzed, for which we could f...

The regioselectivity and the photochemical efficiency were investigated in the Paternò-Büchi reaction of 1,3-dimethylthymine (DMT) and 1,3-dimethyluracil (DMU) with benzophenone (1b) and some 4,4'-disubstituted derivatives (dimethoxy (1a), difluoro (1c), dichloro (1d), dibromo (1e) and dicyano benzophenone (1f)) that gives rise to two regioisomeric oxetanes, 2 and 3. The regioselectivity (the r...

We report the regioselective synthesis of dihydroisoquinolones from aliphatic alkenes and O-pivaloyl benzhydroxamic acids mediated by a Rh(III) precatalyst bearing sterically bulky substituents. While the prototypical Cp* ligand provides product with low selectivity, sterically bulky Cpt affords product with excellent regioselectivity for a range of benzhydroxamic acids and alkenes. Crystallogr...

Product regioselectivity as influenced by molecular recognition is a key aspect of enzyme catalysis. We applied large-scale two-dimensional (2D) umbrella sampling (USP) simulations to characterize acetaminophen (APAP) binding in the active sites of the family of Cytochrome P450 (CYP) enzymes as a case study to show the different regioselectivity exhibited by a single substrate in comparative en...

The protecting group tetraisopropyldisiloxane-1,3-yl has been investigated for simultaneous protection of two hydroxyls on pentopyranosides. Methyl α-D-xylopyranoside is protected in excellent regioselectivity and high yield to form the 2,3-protected xylopyranoside whereas methyl β-D-xylopyranoside gives the 3,4-protected product also with excellent regioselectivity.

The condensation of 5-alkoxycarbonyl-1H-pyrrolediones with cyclic ketazinones was systematically investigated. It was discovered that the regioselectivity of this reaction can be easily swapped between two alternative directions affording derivatives of partially hydrogenated indole or benzofurane. The control of this regioselectivity is efficiently governed by steric effects at the hydrazone m...