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There are many more pairs of diastereomers, because each of these configurations is a diastereomer with respect to every other configuration excluding its own enantiomer (for example, R,R,R is a diastereomer of R,R,S; R,S,R; and R,S,S). For n = 4, there are sixteen stereoisomers, or
For example, the image below shows the addition of ethylmagnesium bromide to ethyl sorbate 1 using a copper catalyst with a reversed josiphos (R,S)-(–)-3 ligand. [35] This reaction produced the 1,6-addition product 2 in 0% yield, the 1,6-addition product 3 in approximately 99% yield, and the 1,4-addition product 4 in less than 2%
Stereochemistry, a subdiscipline of chemistry, studies the spatial arrangement of atoms that form the structure of molecules and their manipulation. [1] The study of stereochemistry focuses on the relationships between stereoisomers, which are defined as having the same molecular formula and sequence of bonded atoms (constitution) but differing in the geometric positioning of the atoms in space.
Enantioselective synthesis, also called asymmetric synthesis, [1] is a form of chemical synthesis.It is defined by IUPAC as "a chemical reaction (or reaction sequence) in which one or more new elements of chirality are formed in a substrate molecule and which produces the stereoisomeric (enantiomeric or diastereomeric) products in unequal amounts."
Two kinds of stereoisomers. In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space.
Absolute configuration showing the determination of the R and S descriptors. In chemistry, absolute configuration refers to the spatial arrangement of atoms within a molecular entity (or group) that is chiral, and its resultant stereochemical description. [1]
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The Cram's rule of asymmetric induction named after Donald J. Cram states In certain non-catalytic reactions that diastereomer will predominate, which could be formed by the approach of the entering group from the least hindered side when the rotational conformation of the C-C bond is such that the double bond is flanked by the two least bulky groups attached to the adjacent asymmetric center. [3]