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Highly stereoselective additions of certain 2-lithio-1,3-dithianes to cyclohexanones. Solvent effects

โœ Scribed by Eusebio Juaristi; Ernest L. Eliel

Publisher
Elsevier Science
Year
1977
Tongue
French
Weight
242 KB
Volume
18
Category
Article
ISSN
0040-4039

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โœฆ Synopsis

In a series of important papers 192 Nguyen Trong Anh and collaborators have discussed the importance of charge control vs. orbital control3 in reaction of nucleophiles with ambident4 sub-strates. Hard nucleophiles5 react in charge-controlled fashion whereas orbital control tends to prevail for soft nucleophiles.5 Thus the observation 697 that hard bases attack anancomeric8 cyclohexanones predominantly from the axial side (unless steric effects are overwhelming) whereas soft bases lead to preferential equatorial attack has been explained by reasoning' that charge control should be operative mainly in axial approach whereas equatorial approach should be orbitalcontrolled.

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