Reduction of Aldehydes and Ketones
• Complete reduction of a carbonyl group to a
methylene (-CH2-) group is possible by two different
methods
1) Wolff-Kishner reduction:
• Highly basic conditions
• Extension of imine formation
19.12 Reduction of Carbonyl Groups to Methylene Groups
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Reduction of Aldehydes and Ketones
19.12 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
19.12 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
19.13 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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