Dieckmann reaction ring size

Condensations Highly atom economical since small molecules of water or alcohol are liberated Atom economy increases as the molecular weights of the combining fragments increases For cyclization reactions such as the Dieckmann condensation and the synthesis of cyclic ethers from straight chain diols the atom economy increases with increasing ring size... 

This interesting reaction is especially useful for the synthesis of medium- and large-ring compounds from dicarboxylic esters, and is effective for ring sizes that cannot be made by the Dieckmann condensation or decarboxylation (Section 18-1 OB). Radical anions formed by addition of sodium to the ester... 

From a synthetic point of view, the titanium-induced mframolecular cyclization of dicarbonyl compounds is especially attractive in that carbocyclic rings of all sizes may be prepared in good yields, competitive with those obtained using the Dieckmann and acyloin cyclization methods. The synthesis of medium- and large-ring cycloalkenes by the McMurry reaction requires high-dilution conditions (< 0.0 IM) to repress intermol-ecular polymerization. ... 

The size of the ring being formed has a great influence on the course of the reaction. When 193 was treated with sodium ethoxide, three isomeric Dieckmann products were possible, 194-196. Reaction of the enolate via path a could generate a three-membered ring but this is energetically less favorable. Attack... 

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