666857-71-2Relevant academic research and scientific papers
Demonstrating the Synergy of Synthetic, Mechanistic, and Computational Studies in A Regioselective Aniline Synthesis
Davies, Ian W.,Marcoux, Jean-Francois,Kuethe, Jeffery T.,Lankshear, Michael D.,Taylor, Jeremy D. O.,Tsou, Nancy,Dormer, Peter G.,Hughes, David L.,Houk,Guner, Vildan
, p. 1298 - 1308 (2007/10/03)
Tri- and tetrasubstituted anilines are formed in good to excellent yields by the addition of ketones to vinamidinium salts (up to 98%). The reaction proceeds via the formation of dienone intermediates, which react to form an enamine with the liberated amine. In the case of a nitro, or dimethylaminomethylene substituent, the enamines undergo a facile electrocyclic ring closure to form a cyclohexadiene, which goes on to form anilines with a high degree of selectivity (up to 50:1) with a minor competing pathway proceeding via the enol providing phenols. Competition experiments using isotopic substitution reveal that the rate determining step en route to dienone is enol/enolate addition to the vinamidinium salt, which is characterized by an inverse secondary isotope effect (kH/D 0.7-0.9). Computational studies have been used to provide a framework for understanding the reaction pathway. The original proposal for a [1,5]-H shift was ruled out on the basis of the calculations, which did not locate a thermally accessible transition state. The minimum energy conformation of the enamine is such that a facile electrocyclic ring closure is ensured, which is corroborated by the experimental studies. A framework for understanding the reaction pathway is presented.
Conversion of Benzal Halides to Benzaldehydes in the Presence of Aqueous Dimethylamine
Bankston, Donald
, p. 283 - 289 (2007/10/03)
Aqueous dimethylamine is an efficient reagent for the conversion of a variety of benzal halides to their corresponding benzaldehydes. Studies indicate that aqueous dimethylamine significantly accelerates aldehyde formation from benzal halide precursors, as compared to the use of water alone. Indeed, these reactions are routinely completed in one hour or less, depending upon substrate substitution. Desired products can be isolated in pure form, and in high yield, but silica gel filtration is often necessary to remove baseline contaminants. The method represents a novel, economical approach to acquire pure, substituted benzaldehydes from commercially available, or easily prepared starting materials.
