Reduction of Aldehydes and Ketones

• Complete reduction of a carbonyl group to a methylene (-CH2-) group is possible by two different methods1) Wolff-Kishner reduction:

• Highly basic conditions• Extension of imine formation

119.12 Reduction of Carbonyl Groups to Methylene Groups

Reduction of Aldehydes and Ketones

219.12 Reduction of Carbonyl Groups to Methylene Groups

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Reduction of Aldehydes and Ketones

2) Clemmensen reduction:

• Acidic conditions• Zinc amalgam + HCl

• The mechanism is uncertain

519.12 Reduction of Carbonyl Groups to Methylene Groups

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Problems

1) Draw the products for the following reactions:

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2) Draw the complete mechanism for the following reaction:

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The Wittig Alkene Synthesis

• Method of preparing alkenes from aldehydes and ketones

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• Regioselective rxn, assuring the location of alkene

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The Wittig Alkene Synthesis

• Preparation of phosphorous ylide

• Ylid (or ylide): compound with opposite charges on adjacent, covalently bound atoms

1119.13 The Wittig Alkene Synthesis

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The Wittig Alkene Synthesis

• Stereochemistry– Both E and Z products

• Retrosynthetically

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Problems

1) Draw the product(s) for the following reaction

2) What carbonyl compound and phosphorus ylide might you use to prepare the following compound?

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