19.42 Although codeine occurs in low concentration in the opium poppy, mostof the codeine used in medicine is prepared from morphine (the principalcomponent of opium) by the following reaction. Explain why selectivemethylation occurs at only one OH in morphine to give codeine. Codeineis a less potent and less addictive analgesic than morphine.HOHOmorphineN[1] KOH[2] CH₂IwwwwwwHOcodeineN

Approach to solving the question: As we know, KOH is a strong base and abstract the most acidic…

Answered: 19.42 Although codeine occurs in low…

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter16: Aldehydes And Ketones

Section: Chapter Questions

Problem 16.79P

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MeO 22.55 One potential synthesis of the anti-inflammatory and analgesic drug nabumetone is chloromethylation (Problem 22.48) of 2-methoxynaphthalene followed by an acetoacetic ester synthesis (Section 19.6). 5 3 6 CH₂O CI acetoacetic ester synthesis HC 7 MeO MeO 1 8 2-Methoxynaphthalene Nabumetone (a) Account for the regioselectivity of chloromethylation at carbon 6 rather than at carbon 5 or 7. (b) Show steps in the acetoacetic ester synthesis by which the synthesis of nabum- etone is completed.
17.36 Tamoxifen is an estrogen receptor modulator that is used in the treatment of breast cancer. Provide the missing reagents and the structure of compound A in the synthesis of tamoxifen. Page 707 HO (CH3)2N 1. C,H,MgBr 2. H + Compound A (CH3)2N Tamoxifen
16.51 Propose a plausible mechanism for the following transformation: Heat
Reaction of X and phenylacetic acid forms an intermediate Y, which undergoes an intramolecular reaction to yield rofecoxib. Rofecoxib is a nonsteroidal anti-inflammatory agent once marketed under the trade name Vioxx, now withdrawn from the market because of increased risk of heart attacks from long-term use in some patients. Identify Y and draw a stepwise mechanism for its conversion to rofecoxib.
19.57 Because phenol (C6H5OH) is less acidic than a carboxylic acid, it can be deprotonated by NaOH but not by the weaker base NaHCO3. Using this information, write out an extraction sequence that can be used to separate C6H5OH, benzoic acid, and cyclohexanol. Show what compound is present in each layer at each stage of the process, and if it is present in its neutral or ionic form.
18.4 Characteristic Reactions of Anhydrides, Esters, and Amides 4 What product forms when ethyl benzoate is treated with each of the following sets? (a) H₂O, NaOH, heat H(b) H₂O, HCl, heat
Reaction of X and phenylacetic acid forms an intermediate Y, which undergoes an intramolecular reaction to yield rofecoxib. Rofecoxib is a nonsteroidal anti-inammatory agent once marketed under the trade name Vioxx, now withdrawn from the market because of increased risk of heart attacks from long-term use in some patients. Identify Y and draw a stepwise mechanism for its conversion to rofecoxib.
18.26 Predict the products of the following ether cleavage reactions: LOCH CH3 OC(CH3)3 (a) HI CF3CO,H, ? (b) H2O HI HI (c) Н,С— СНОСH,CH, (d) (CH3);CCH,OCH,CH3 H20 H2O
One step in the synthesis of the antihistamine fexofenadine (Section 23.5) involves acid-catalyzed hydration of the triple bond in A. Draw a stepwise mechanism for this reaction and explain why only ketone B is formed.
Acetanilide is less reactive than aniline toward eletrophilic substitution. Explain.
Aziridines are heterocycles that contain an N atom in a three-membered ring. Like epoxides, aziridines are strained and reactive because the 60° bond angles of the three-membered ring deviate greatly from the theoretical tetrahedral bond angle. One step in the synthesis of the drug oseltamivir (trade name Tamiflu, Section 3.2) involves the conversion of amine X to diamine Y, a reaction that occurs by way of an intermediate aziridine. Draw a stepwise mechanism for the conversion of X to Y. Indicate the structure of the aziridine intermediate, and explain the trans stereochemistry of the two amines in Y.
18.31 Aldehydes that have no a hydrogen undergo an intermolecular oxidation-reduction called the Cannizzaro reaction when they are treated with concentrated base. An example is the following reaction of benzaldehyde: ororo H HO™ OH H₂O 2 + (a) When the reaction is carried out in D₂O, the benzyl alcohol that is isolated contains no deuterium bound to carbon. It is CBH-CH₂OD. What does this suggest about the mechanism for the reaction? (b) When (CH3)2CHCHO and Ba(OH)₂/H₂O are heated in a sealed tube, the reaction produces only (CH3)₂CHCH₂OH and [(CH3)₂CHCO₂]2Ba. Provide an explanation for the formation of these products.

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