The drug sildenafil, sold under the trade name Viagra, is a potent inhibitor of phos- phodiesterase V (PDE V), an enzyme found in high levels in the corpus cavernosum of the penis. Inhibitors of this enzyme enhance vascular smooth muscle relaxation and are used for treatment of male impotence. Following is an outline for a synthesis of sildenafil. H Me Me EtO N„H4 EtO (1) EtO НО (2) (3) (4) Pr Pr Pr Me Me Me Но H,N H,N (6) EtO (7) O,N H,N Pr Pr Pr Me Me Me H, Н. Н. EtO EtO EtO Pr Pr Pr 0=$=0 0=$=0 Sildenafil (Viagra) ČH3

The drug sildenafil, sold under the trade name Viagra, is a potent inhibitor of phos- phodiesterase V (PDE V), an enzyme found in high levels in the corpus cavernosum of the penis. Inhibitors of this enzyme enhance vascular smooth muscle relaxation and are used for treatment of male impotence. Following is an outline for a synthesis of sildenafil. H Me Me EtO N„H4 EtO (1) EtO НО (2) (3) (4) Pr Pr Pr Me Me Me Но H,N H,N (6) EtO (7) O,N H,N Pr Pr Pr Me Me Me H, Н. Н. EtO EtO EtO Pr Pr Pr 0=$=0 0=$=0 Sildenafil (Viagra) ČH3

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

Chapter19: Enolate Anions And Enamines

Section: Chapter Questions

Problem 19.63P

See similar textbooks

Similar questions

The compound acetophenone has a very similar molar mass to that of benzoic acid and benzamide. However, acetophenone has a much lower m.p. (20 °C) than both such that, by contrast, it is a liquid at room temperature. By considering intermolecular forces and comparing functional group structure, account for this big difference in physical properties.
Compound I (C11H14O2) is insoluble in water, aqueous acid, and aqueous NaHCO3, but dissolves readily in 10% Na2CO3 and 10% NaOH. When these alkaline solutions are acidified with 10% HCl, compound I is recovered unchanged. Given this information and its 1H-NMR spectrum, deduce the structure of compound I.
Amines are converted into alkenes by a two-step process called Hofmann elimination. SN2 reaction of the amine with an excess of CH3I in the first step yields an intermediate that undergoes E2 reaction when treated with silver oxide as base. Pentylamine, for example, yields 1-pentene. Propose a structure for the intermediate, and explain why it readily undergoes elimination.
One step in the urea cycle for ridding the body of ammonia is the conversion of argininosuccinate to the amino acid arginine plus fumarate. Propose a mechanism for the reaction, and show the structure of arginine.
A step in a synthesis of PGE1 (prostaglandin E1, alprostadil) is the reaction of a trisubstituted cyclohexene with bromine to form a bromolactone. Propose a mechanism for formation of this bromolactone and account for the observed stereochemistry of each substituent on the cyclohexane ring. Alprostadil is used as a temporary therapy for infants born with congenital heart defects that restrict pulmonary blood flow. It brings about dilation of the ductus arteriosus, which in turn increases blood flow in the lungs and blood oxygenation.
Following is a synthesis for toremifene, a nonsteroidal estrogen antagonist whose structure is closely related to that of tamoxifen. (a) This synthesis makes use of two blocking groups, the benzyl (Bn) group and the tetrahydropyranyl (THP) group. Draw a structural formula of each group and describe the experimental conditions under which it is attached and removed. (b) Discuss the chemical logic behind the use of each blocking group in this synthesis. (c) Propose a mechanism for the conversion of D to E. (d) Propose a mechanism for the conversion of F to toremifene. (e) Is toremifene chiral? If so, which of the possible stereoisomers are formed in this synthesis?
As far back as the 16th century, South American Incas chewed the leaves of the coca bush, Erythroxylon coca, to combat fatigue. Chemical studies of Erythroxylon coca by Friedrich WĂ¶hler in 1862 resulted in the discovery of cocaine, C17H21NO4, as the active component. Basic hydrolysis of cocaine leads to methanol, benzoic acid, and another compound called ecgonine, C9H15NO3. Oxidation of ecgonine with CrO3 yields a keto acid that readily loses CO2 on heating, giving tropinone. (a) What is a likely structure for the keto acid? (b) What is a likely structure for ecgonine, neglecting stereochemistry? (c) What is a likely structure for cocaine, neglecting stereochemistry?
Show how the synthetic scheme developed in Problem 23.67 can be modified to synthesize this triiodobenzoic acid X-ray contrast agent.
Phenacetin is an analgesic compound having molecular formula C10H13NO2. Once a common component in over-the-counter pain relievers such as APC (aspirin, phenacetin, caffeine), phenacetin is no longer used because of its liver toxicity. Deduce the structure of phenacetin from its 1H NMR and IR spectra.
γ-Butyrolactone (C4H6O2, GBL) is a biologically inactive compound that is converted to the biologically active recreational drug GHB (Section 19.5) by a lactonase enzyme in the body. Since γ-butyrolactone is more fat soluble than GHB, it is more readily absorbed by tissues and thus produces a faster onset of physiological symptoms. γ-Butyrolactone shows an absorption in its IR spectrum at 1770 cm−1 and the following 1H NMR spectral data: 2.28 (multiplet, 2 H), 2.48 (triplet, 2 H), and 4.35 (triplet, 2 H) ppm. What is the structure of γ-butyrolactone?
The following three derivatives of succinimide are anticonvulsants that have found use in the treatment of epilepsy, particularly petit mal seizures. Q. Of these three anticonvulsants, one is considerably more acidic than the other two. Which is the most acidic compound? Estimate its pKa and account for its acidity. How does its acidity compare with that of phenol? with that of acetic acid?
What starting materials are needed to prepare the compound below by intramolecular Michaelreaction?