Absolute Asymmetric Synthesis under Physical Fields:  Facts and Fictions

Asymmetric Autocatalysis and Its Implications for the Origin of Homochirality

“…The subject of absolute asymmetric synthesis has captivated scientists ever since the biological importance of L-amino acids and D-sugars was first recognized (9)(10)(11)(12). We understand that when we go into the laboratory to prepare such molecules, we will arrive at a racemic mixture unless we employ a template; an asymmetric enzyme, reagent or catalyst, a chiral synthon, or some other physical or chemical force, to help direct the reaction toward the desired hand of the product.…”

Stirring competes with chemical induction in chiral selection of soft matter aggregates

“…In particular, one anticipates that achiral substances can be transformed, at most, into a racemic mixture of equally represented enantiomers, or into an enantiopure system with equal probability for the two enantiomers. Apart from the handedness imparted by proto-chiral organizing surfaces 3 , oriented reacting interfaces 4 , and aligning 5 or confining 6 boundaries, the balance above may be broken under the intervention of one within a few physical forces of signed helicity 7,8 , or through the effect of a chiral chemical modifier. In general terms, there is still the pending issue of whether a chiral physical force may be opposed in an effective way to a chiral chemical intervention.…”

An Introduction to Chirality at the Nanoscale

“…The production of an ee in more general situations is often referred to as absolute enantioselection or physical chiral induction. The subject still attracts much interest and controversy [12,13,15,67]. The considerations of Section 1.3.3 above provide a sound foundation for the critical assessment of physical influences capable of inducing ees, however small.…”

“…The ability of a truly chiral influence to induce absolute asymmetric synthesis in a reaction process at equilibrium may be illustrated by a simple symmetry argument applied to the following unimolecular process [12,13,15,67]. Photochemistry with circularly polarized light is especially favorable because it conforms to Jaegers dictum above.…”

“…There has been considerable interest in the possibility that vortex motion in a conical swirl might be exploited to induce absolute enantioselection, but until recently no convincing example has been demonstrated experimentally [67]. Then -several years ago reports appeared of mirror-symmetry breaking in homoassociation of achiral diprotonated porphyrins where helical conformations were generated by stirring in a rotary evaporator with the sense of chirality, detected by circular dichroism, being selected by the sense of stirring [70,71].…”