Spatial isomers

The number of spatial isomers increases with increasing number of asymmetric carbon centres with the addition of each new asymmetric centre, the number of isomers doubles. The trihydroxy glutaric acid molecule has three identical asymmetric carbon atoms. 

Spatial isomers are also found in several nitrite-anion complex compounds [117] in an angle, as in 98, and trans-planar 99 ... 

Forasmuch as neither of initial compounds was separated into spatial isomers (though the affinity to enrichment of a mixture of trans-isomers was observed), synthesized polymers possessed atactic structure. 

Supramolecular stabilization means stabilization of certain chemical species, their different forms, and assemblies in a particular supramolecular environment. Supramolecular stabilization is responsible for the existence of "energetically unfavorable" conformations, different spatial isomers, unexpected oligomers, "unstable" molecules. highly reactive radicals, elements in unusual oxidation states, certain ionic species, and so on, in supramolecular phases. Such species decompose, change, or equilibrate with alternative forms once they are brought out of their "stabilizing" environment. The best-known chemical reaction based strictly on supramolecular stabilization is the so-called "blue reaction." where iodine reversibly polymerizes in the presence of starch. 

GC analyses employing chiral stationary phases can be used to separate all kinds of spatial isomers containing any type of chiral atom. The only prerequisite is that the solutes are either intrinsically volatile or derivatives can be formed that are adequately volatile. 

Spatial isomers have been identihed in the more stable t-butyl derivative (6.689). Ring expansion occurs on heating this compound with sulphur (6.690). 

Thermal black Carbopack C Carbopack F Sterling HT Sterling FT 6-12 Medium boiling compounds, structural and spatial isomers... 

Stereochemistry of Polycyclic Systems. Two aspects of the stereochemistry of polycyclic compounds are of the greatest interest for the total synthesis of steroids, namely the comparative stability of the spatial isomers of these compounds and the influence on them of double carbon-carbon bonds in various positions of the cyclic system. 

From the keto esters A, B, and C (119, 124, 123) were also obtained five spatial isomers of doisynolic acid [233, 235] by the method described previously (Schemes 3 and 11) for the synthesis of bis - and monodehydro-doisynolic acids. The structures assigned to them apparently require additional confirmation, since they are not fully in agreement with the formulas of the initial keto esters given in Scheme 12. 

We used the small organic compound tris-(bromometliyl)benzene (TBMB 1) as a scaffold to anchor peptides containing three cysteine residues (Fig. la). Tire reaction occurs in aqueous solvents at room temperature (20-25 C), and die threefold rotational symmetry of die TBMB molecule ensures die formation of a unique structural and spatial isomer. 

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