Easy organic synthesis rule

E. Rule number five the easy organic synthesis (EOS) rule... 

A Rule 1 The minor modifications rule B Rule 2 The biological logic rule C Rule 3 The structural logic rule D Rule 4 The right substituent choice E Rule 5 The easy organic synthesis (EOS) rule... 

Lithium enolates 85 and silyl enol ethers 86 are probably widest in application in modern organic synthesis. The basic rules of selectivity were laid down in chapters 2-4 where many examples were given. We shall simply summarise the position and add some extra versatility from chapters 5-9. These two methods must be taken together because easy interconversion means that a way of making one is a way of making another. In addition, the silyl enol ethers 86 are a source of naked enolates 87 when fluoride is used to remove silicon in the absence of a metal cation. Tetra-alkyl ammonium fluorides such as TBAF (Bu4N+ I ) are usually used. 

From the results reviewed above, one might get the impression that the choice of an organic solvent that optimizes the enantioselectivity of the enzyme in a given resolution reaction is a matter of tedious trial and error, with little guidance from established rules or insights. In practice, however, one has to consider several mitigating circumstances. In many cases of interest, the choice will be limited to a relatively small number of solvents that are either industrially approved or readily available in the laboratory. Since most practical resolutions start from a racemic mixture obtained by chemical synthesis, batch-mode enrichment requiring relatively modest 5-values will be an attractive method. In that case, solubility and easy... 

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