Stereogenic centre/elements

The compound has two chirality centres and three pseudo chirality centres. There is however, only one (achiral) diastereomer of the compound shown in the question. The two isomers can be distinguished from one another solely on the relative position of the chlorine or bromine atoms which lie in a plane which also happens to be the plane of symmetry of the molecule (this is the only symmetry element present, therefore the symmetry point group is Cs). It is possible in this instance to specify the configuration unequivocally using the descriptors E and Z. However, in systematic nomenclature the complete configuration of all the stereogenic centres is specified. Thus the (so-called) Z isomer is (ls,3r,5 ,6r,7S)-l,6-dibromo-3,6-dichloroadamantane and the isomer is (ls,3r,5 ,6s,7S)-l,6-dibromo-3,6-dichloroadamantane, i.e. the two isomers can be distinguished simply by the descriptor used for position 6. 

Chiral atoms are stereogenic, but not all stereogenic centres are chiral atoms. For example, in an alkene abC=Cab the double bond is a stereogenic element. 

One key element of the total synthesis of (-)-dactylolide (-)- developed by McLeod et al. is a [3,3]-sigmatropic Ireland-Claisen rearrangement which allows the selective formation of the stereogenic centre at C-19. 

There are a number of syn SE2 reactions, which are significantly different in nature. The electrophile is typically an aldehyde, which is coordinated at the time of reaction to the electropositive group on the stereogenic centre, characteristically a metal like boron, tin, zinc or a silyl group carrying one or more electronegative elements. These reactions are cyclic in nature, usually use chair-like transition structures, are... 

Most organic molecules incorporate at least one stereogenic element (centre, plane or axis) [26] and may, therefore, exist in more than one stereoisomeric form. These stereoisomers, as far as mechanistic argument is concerned, are distinct species, and the kinetics and... 

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