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Quiz 2

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  • 1. Give the best answer for the following multiple choice and labeling questions.

    a) Which of the following will not react with a grignard reagent?

    A) butyraldehyde

    B) butan-2-one

    C) 2-butanol

    D) 1-butene

    E) 1-butyne

    b) The addition of a grignard reagent to a carbonyl is based on collision of a nucleophile to fill what acceptor orbital?

    A) a s bonding orbital

    B) a s* antibonding orbital

    C) an empty p orbital

    D) a p bonding orbital

    E) a p* antibonding orbital

    c) Which reactions will not give a product as a racemic mixture?

    A) the addition of phenyl grignard to propionaldehyde

    B) epoxidation of an allylic alcohol with a Ti(OiPr)4, tBuOOH, and (–)-diethyl tartrate

    C) the addition of NaOCH3 to cyclohexene oxide

    D) the acid-catalyzed addition of methanol to cyclohexene oxide

    E) an SN1 reaction

    d) Which of the following is not a true statement:

    A) a silyl ether bond can be cleaved by a fluoride source, such as TBAF

    B) LiAlH4 is an oxidizing agent

    C) epoxide formation using mCPBA with an alkene proceeds via a concerted mechanism

    D) H2CrO4 will oxidize a secondary alcohol to a ketone

    E) arene oxides can react with DNA and initiate cancer-causing pathways

    e) In the boxes provided, indicate whether each of the following reactive carbon atoms is considered to be electrophilic (E) or nucleophilic (N). R is used to indicate either H or alkyl.

    2. Draw the resonance contributor for a ketone, showing any curved arrows for its formation. Briefly explain what this resonance indicates about the reactivity of a carbonyl.

    3. Ethylene oxide is the starting material for the synthesis of “Cellosolve”, an important industrial solvent. Provide a curved arrow mechanism for this reaction.

    4. Provide a curved arrow mechanism for the following transformation.

    5. Synthesis

    a) Show how to synthesize the following alcohol where all carbons in the molecule must come from compounds with 3 or fewer carbon atoms. Include all necessary reagents for the synthesis you propose.

    b) Explain why you would need to use a protecting group strategy in a synthesis and give an example of a synthesis that requires the use of a protecting group. Your synthesis must have at least 3 steps to receive full credit.

    6. An aziridinium ion follows a similar reactivity pattern to an epoxide. The following aziridinium ion reacts with NaOCH3 to form compounds A and B. Given what you know about the reactivity patterns of epoxides and the information given below, identify the structures of both compounds A and B (in boxes provided).