Achiral organic compounds

Asymmetric Autocatalysis Triggered by Chiral Organic Crystals Composed of Achiral Organic Compounds... 

In these systems, after the crystal chirality induced the chirality of asymmetric carbon in external organic compound, the subsequent asymmetric autocatalysis gives the greater amount of enantiomerically amplified product. These results clearly demonstrate that the crystal chirality of achiral organic compound is responsible for the enantioselective addition of /-Pr2Zn to pyrimidine-5-carbalde-hyde Ic. 

Enantioselective Synthesis Mediated by Chiral Crystals of an Achiral Organic Compound in Conjunction with Asymmetric Autocatalysis... 

Some achiral organic compounds form chiral crystals, with each crystal exhibiting one of two possible enantiomorphs [9-13]. These chiral crystals composed of an achiral organic compound may serve as an efficient chiral seed in a prebiotic world, therefore, a study of asymmetric autocatalysis using these chiral organic crystals is an interesting subject. 

Chiral organic crystals composed of achiral compounds such as hippuric acid act as the initial source of chirality of asymmetric autocatalysis to produce the highly enantiomerically pure product. In this reaction, chiral organic crystals are utilized as a chiral inducer, not as a reactant. Therefore, these results are the realization of the process in which the crystal chirality of achiral organic compounds induces asymmetry in another organic compound whose chirality was amplified to produce a large amount of enantiomerically pure organic compound, pyrimidyl alkanol in conjunction with asymmetric autocatalysis. 

A number of apparent achiral organic compounds have been obtained as chiral crystals, and the solid-state photoreaction gave many successful absolute asym-... 

There is no special crystallization technique required to prepare chiral crystals from achiral organic compounds. Ordinary crystallization techniques can be employed i.e., a hot saturated solution of a compound in a suitable solvent is slowly cooled, or a saturated solution is slowly evaporated to obtain crystals. Whether the molecule is chiral can be easily differentiated by the measurement of optical rotation in solution using a polarimeter. However, there are great difficulties in measuring the optical rotation of crystalline substances due to the large birefringence [33]. Solid-state circular dichroism (CD) spectral measurements of... 

The host-guest and ionic chiral auxiliary approaches have been most intensively applied for solid-state asymmetric induction. A number of achiral organic compounds could be converted into chiral compounds in high enantioselectivities. However, all the photoreactions in themselves are well-known intramolecular photoreactions photocyclization, [2 + 2] photocyclization, Norrish type II photo-cyclization, di-ir-methane photorearrangement and photoisomerization. New types of asymmetric photoreactions have never been reported. 

Process of crystallization of achiral organic compounds can also generate chirality. Compounds that crystallize in chiral form belong to various classes of organic compounds, including substituted benzene derivatives, polyaryl and polycychc derivahves, heterocyclic compounds, etc. These compounds were reviewed in short in literature [4]. It is evident that chirality of this type occurs only in crystalhne form and disappears upon dissolution. 

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