B-Damascenone belongs to a family of fragrant natural products called rose ketones that have been used in the perfume industry. In one synthesis of B-damascenone, the reaction of compound 1 with one equivalent of MCPBA afforded two constitutionally isomeric epoxides (compounds 2 and 3), which were then converted into diol 4 upon subsequent treatment with aqueous acid. Identify the structures of epoxides 2 and 3, and propose a mechanism that converts each of them into compound 4 in the presence of H30+. OCH OH OCH, МСВРА H,0" 2 +3 (one equiv.) OH B-Damascenone

B-Damascenone belongs to a family of fragrant natural products called rose ketones that have been used in the perfume industry. In one synthesis of B-damascenone, the reaction of compound 1 with one equivalent of MCPBA afforded two constitutionally isomeric epoxides (compounds 2 and 3), which were then converted into diol 4 upon subsequent treatment with aqueous acid. Identify the structures of epoxides 2 and 3, and propose a mechanism that converts each of them into compound 4 in the presence of H30+. OCH OH OCH, МСВРА H,0" 2 +3 (one equiv.) OH B-Damascenone

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

Chapter21: Benzene And The Concept Of Aromaticity

Section: Chapter Questions

Problem 21.64P: Following is a synthesis for toremifene, a nonsteroidal estrogen antagonist whose structure is...

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Q4 B-Damascenone belongs to a family of fragrant natural products called rose ketones that have been used in the perfume industry. In one synthesis of B-damascenone, the reaction of compound 1 with one equivalent of MCPBA afforded two constitutionally isomeric epoxides (compounds 2 and 3), which were then converted into diol 4 upon treatment with aqueous acid. Identify the structures of epoxides 2 and 3, and propose a mechanism that converts each of them into compound 4 in the presence of H,O*. (Note: It is reasonable to presume that a protonated epoxide can open by itself, without the involvement of a nucleophile, if doing so will give a resonance-stabilized allylic carbocation intermediate.)? OCH, OH OCH3 H,O 2+3 MCPBA (one equiv.) 4 OH B-Damascenone
(c) Treating lactone B with two equivalents of phenylmagnesium bromide, followed by hydrolysis in aqueous acid, gives a compound with the molecular formula C18H22O2, as shown below. Propose a structural formula for this compound. 1. PhMgBr (2 eq.) 2. H'/H>O C18H2202 bj 1o 14 10I f6 40 & 3 4 00 (8)
Draw a structural formula for the product formed by treating butanal with each reagent. (a) LiA1H4LiA1H4 followed by H2OH2O (b) NaBH4NaBH4 in CH3OH/H2O (c) H2/Pt (d) Ag(NH3)2+in NH3/H2O (e) H2CrO4, heat (f) HOCH2CH2OH,HCl
In an aqueous solution containing sodium bicarbonate, aniline reacts quickly withbromine to give 2,4,6-tribromoaniline. Nitration of aniline requires very strong conditions,however, and the yields (mostly m-nitroaniline) are poor.(a) What conditions are used for nitration, and what form of aniline is present under theseconditions?
Identify products A and B from the given 1H NMR data. Treatment of acetone [(CH3)2C=O] with dilute aqueous base forms B. Compound B exhibits four singlets in its 1H NMR spectrum at 1.3 (6 H), 2.2 (3 H), 2.5 (2 H), and 3.8 (1H) ppm. What is the structure of B?
When acetonitrile is treated with concentrated sulfuric acid and tert-butanol, followed by water, a product is formed whose 'H NMR spectrum exhibits the following three signals: singlet, 1.3 ppm, 9 H; singlet, 2.0 ppm, 3 H; and broad singlet, 8.2 ppm, 1 H. Its IR spectrum exhibits one broad absorption of medium intensity between 3300 and 3500 cm-1, and a narrow, intense absorption near 1650 cm¯1. A key intermediate is shown. Draw the structure of the product, and draw the complete, detailed mechanism for the reaction. CH3 CH3 H2SO4 (conc) H2O ? + H3C H3C H3C-C=Ñ-c `CH3 CH3 HO
An unknown compound A of molecular formula C10H18O reacts with H2SO4 to form two compounds (B and C)of molecular formula C10H16. B and C both react with H2 in the presence of Pd-C to form decalin. Ozonolysis of B forms D, and ozonolysis of C forms a diketone E of molecular formula C10H16O2. Identify the structures of compounds A, B, C, and E.
Several sulfonylureas, a class of compounds containing RSO2NHCONHR, are useful drugs as orally active replacements for injected insulin in patients with adult-onset diabetes. These drugs decrease blood glucose concentrations by stimulating b cells of the pancreas to release insulin and by increasing the sensitivity of insulin receptors in peripheral tissues to insulin stimulation. Tolbutamide is synthesized by the reaction of the sodium salt of p-toluenesulfonamide and ethyl N-butylcarbamate . Propose a mechanism for this step.
As a method for the synthesis of cinnamaldehyde (3-phenyl-2-propenal), a chemist treated 3-phenyl-2-propen-1-ol with K2Cr2O7 in sulfuric acid. The product obtained from the reaction gave a signal at δ5 in its 13C NMR spectrum. Alternatively, when the chemist treated 3-phenyl-2-propen-1-ol with PCC in CH2Cl2, the 13C NMR spectrum of the product displayed a signal at δ193.8. (All other signals in the spectra of both compounds appeared at similar chemical shifts.) (a) Which reaction produced cinnamaldehyde? (b) What was the other product?
Devise a synthesis of the ketone hexan-3-one, CH3CH2COCH2CH2CH3, from CH3CH2Br as the only organic starting material; that is, all the carbon atoms in hexan-3-one must come from CH3CH2Br. You may use any other neededreagents.
Complete the statements by providing the reagents necessary to complete each step of the synthesis. Ketone reacted with CO₂H and then yielded a derivative, which was treated with 1) (i) C6H5MgBr (ii) H3O+ 2) (i) DIBAL-H (ii). H3O+ 3) Sia2BH,H202, NaOH 4) CH2N2 (diazamethane) CO₂C2H5 5) PCC (an oxidant) 6) H2SO4, H2O, heat 7) HgSO4/ H2SO4 8) C₂H5OH, H3O*, heat TABLE OF REAGENTS to form an unsaturated carboxylic acid, treatment with to yield unsaturated aldehyde as the final product. CHO MacBook Air 9) C6H5 CH2 P(C6H5)3; NaOH 10) PCC (an oxidant) 11) NaCN, H₂SO4 12) PhCH2CHO, H3O*
Discovery of the antibiotic sulphanilamide led to rapid development of a large number of structurally related sulphonamides. Some of these were useful leads to compounds with other medicinal properties. Amongst these, sulfasalazine was active in the treatment of ulcerative colitis, a potentially fatal disease of the colon. As a medicinal chemist, you are about to carry out the synthesis of sulfasalazine, starting from aniline. Give the chemical names and draw the chemical structures of the reagents you will need to use for the all the steps marked (a)-(d). Aniline HO₂C HO (a) N=N- ACHN Ac represents CH3CO Sulfasalazine SO,NH S0,C1 N (b) (d) H₂N- SO,NH (c) N [Oro] SO,NH N Step (a) in question 5 above results in the para product only. Explain why this occurs.