Reduction of Aldehydes and Ketones Complete reduction of

Reduction of Aldehydes and Ketones • Complete reduction of a carbonyl group to a methylene (-CH 2 -) 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 1

Reduction of Aldehydes and Ketones 19. 12 Reduction of Carbonyl Groups to Methylene Groups 2

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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 5

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Problems 1) Draw the products for the following reactions: 7

2) Draw the complete mechanism for the following reaction: 8

The Wittig Alkene Synthesis • Method of preparing alkenes from aldehydes and ketones 9

• Regioselective rxn, assuring the location of alkene 10

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 11

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The Wittig Alkene Synthesis • Stereochemistry – Both E and Z products • Retrosynthetically 13

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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? 15