Chapter 10: Q60P (page 540)

Describes a new method to perform ozonolysis reactions that used pyridine (py) to generate the final aldehydes and ketones in a non-aqueous reaction medium. In a subsequent publication (J. Org. Chem., 2013, 78, 42), Professor Dussault (U. of Nebraska at Lincoln) described a “tandem” process in which two reactions are performed sequentially without having to isolate the intermediate aldehyde or ketone. Show the final product from each sequence. (Hint: The isolated products were from the larger part of the structure. Ignore stereochemistry.)

Short Answer

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Step by step solution

Reagents used to form alcohol

Alkene reacts with ozone in the presence of pyridine to form aldehyde or ketone depending upon the reactant used which then reacts with Grignard reagent and undergoes hydrolysis to form secondary or tertiary alcohol.

Formation of the desired product

a) Ozonolysis of the provided alkene gives formaldehyde which reacts with Grignard reagent (nucleophilic attack) followed by the hydrolysis gives alcohol as the major product.

Formation of product in reaction a

b) Ozonolysis of the provided alkene gives 3-phenyl propanol along with formaldehyde in the product. Nucleophilic attack of the Grignard reagent at the aldehyde group followed by the hydrolysis gives alcohol.

d) Ozonolysis of given alkene gives 4- (tert-butyl) cyclohexanone, Grignard reagent attacks the carbonyl carbon followed by hydrolysis gives the desired product.

e) Ozonolysis of the given alkene gives 6,6 dimethylbicyclo [3.1.1] heptan-2-one. Nucleophilic attack of the Grignard reagent at the carbonyl carbon followed by the hydrolysis gives the desired product.