Anguloselectivity

Preference of a given angulospecific state, to the exclusion of all other angulospecific states, would be characterized by 100% anguloselectivity here, the term angulospecificity, to mean 100% anguloselectivity, is not desirable. 

Angulospecific states refer to partially bonded enhties as in transition states they are not synonymous with conformational states, be it conformations or conformers. Where more than one a bond is formed, the angulospecific state must define the alignment of the elements with respect to each and every a bond that is being formed. We will next discuss the concept of anguloselectivity for (1,1)-, (1,2)- and (2,2)-ligogenic processes. 

It is noted that 3/7 (also 4/8) have identical Newman projections, since the difference consists of a linear ethynyl group. 

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In case 2, the process is also vectoaselective because parallel alignments 127 and 128 are identical. However, in this case the process is anguloselective, because 127a(=128a) and 127b(=128b) are diastereomorphic and, hence, nonisoenergetic entities. 

Figure 14.8. Vectoselectivity and Anguloselectivity in Conformational (1,1 )-Ligogenic Processes...

V. Facioselectivity, Vectoselectivity and Anguloselectivity at Stereotopic Molecular Faces... 

The complete description of processes taking place at stereotopic molecular faces involves three fundamental aspects - facioselectivity, vectoselectivity and anguloselectivity. In order to evaluate the interrationships of the underlying three concepts above, we now consider (1,2)-ligogenic processes for all eleven types of molecular stereofaces. 

We have seen that a given transformation may be anguloselective or nonanguloselective (Figure... 

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