Oxygen-bonded carbonyls structure

Creation of the synthon from the retron. The user carries out on the retron structure the corresponding changes to elaborate the synthon. For example, if we want to convert, in retrosynthetic direction, an alcohol into a carbonyl (the equivalent to a reduction reaction), an alcohol group has to exist in the retron, and the user must indicate "the formation (retrosynthetic) of a carbon-oxygen bond". 

One salient feature of this model of the active site with a bound substrate is that the carbonyl of the peptide bond that is to be broken is coordinated to Zn2+. This feature implies that the metal ion may serve as an electrophile to polarize the carbon-oxygen bond, thereby rendering the carbon succeptible to nucleophilic attack by water. In the x-ray structure a water molecule is... 

The ligand pseudothiohydantoin (110) forms trans-NiL4X2 (Cl, Br, I, C104) and also a cis-NiL4Br2 which probably contains the ligand bonding via the carbonyl oxygen.527 The structures of the octahedral perovskite Sr2[NiW]Oe, and the monoclinic Sr2-[NiTe]Og have been discussed.528... 

This requires that the carbonyl carbon, the nitrogen, and the two atoms attached to each of them (the a-carbon and the oxygen bonded to the carbonyl carbon and the hydrogen and the other a-carbon bonded to the nitrogen) must all lie in the same plane. The most stable conformation has the bulky a-carbons in a trans relationship about the carbon-nitrogen partial double bond, as shown in the preceding structure. 

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