Dolbier HW Solutions 393

Dolbier HW Solutions 393 - 487 ENOLS AND ENOLATES...

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Cyclization of the resulting keto aldehyde is an intramolecular aldol condensation. Base is required. ( d ) The f rst step in this synthesis is the hydration of the alkene function to an alcohol. Notice that this hydration must take place with a regioselectivity opposite to that of Markovnikov s rule and therefore requires a hydroboration oxidation sequence. Conversion of the secondary alcohol function to a carbonyl group can be achieved with any of a number of oxidizing agents. Cyclization of the dione to the f nal product is a base-catalyzed intramolecular aldol conden- sation and was accomplished in 71% yield by treatment of the dione with a 2% solution of sodium hydroxide in aqueous ethanol. 18.30 Intramolecular aldol condensations occur best when a f ve- or six-membered ring is formed. Carbon carbon bond formation therefore involves the aldehyde and the methyl group attached to
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This note was uploaded on 09/28/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.

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