Principles, Concepts, and Strategies of Stereoselective Synthesis

The concept of isomerism is a phenomenon in which certain compounds with the same molecular formula exist in different forms, as a result of their different organizations of atoms. Isomers are defined as compounds having the 

Two levels of comparison are used to describe the molecular structure. The first level excludes three-dimensionality and comprises substances having the same set of atoms but differing in how they are connected in the molecule. Constitutional (structural) isomers are isomers that diDer in the sequence in which atoms are connected to one another, so they can contain different functional groups and/or bonding patterns (e.g., branching). The constitution of molecules (number, kind, and connectivity of atoms) may be represented by a two-dimensional space. There are five types of constitutional (structural) isomerism chain isomerism, positional isomerism, functional isomerism, metamerism, and tautomeiism. 

Chain (skeletal) isomerism is a type of molecular isomerism in which the components of the skeleton (usually carbon skeleton) are distinctly reordered to create 

Stereoselective Synthesis of Drugs and Natural Products, First Edition. Edited by Vasyl Andrushko and Natalia Andrushko. 2013 John Wiley Sons, Inc. Published 2013 by John Wiley Sons, Inc. 

Conformational isomers differ by rotation about single bonds 

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