Concept explainers
Interpretation:
The mechanism thataccounts for each step of the given synthesis is to be written.
Concept introduction:
Cyperone derives its name from the Cyperusrotundus, a nut grass found in tropical, subtropical and temperate regions. It can exist in both
Robinson annulation process is an effective process for the ring formation of six-membered polycyclic compounds, such as lipids and steroids. It works with three important steps, which are as follows: conjugate addition of resonance-stabilized carbanion, aldol condensation, and elimination of hydroxyl ion (
Aldol condensation involves the addition of the aldol (
Michael addition is a reaction that involves the conjugate addition of a resonance-stabilized carbanion for the formation of an enolate.
The reaction thatinvolves the removal of an
The reaction thatinvolves the removal of the
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Organic Chemistry
- Ph3P-CHCH3 H₂C H3C Aldehydes and ketones are converted into alkenes by means of a direct nucleophilic addition called the Wittig reaction. In the reaction, a triphenylphosphorine ylide, also called a phosphorane, adds to an aldehyde/ketone to give a four-membered cyclic intermediate called an oxaphosphetane. The oxaphosphetane is not isolated but instead spontaneously decomposes to release triphenylphosphine oxide and an alkene. CH3 00 + The ylide is formed by reaction of triphenylphosphine, a good nucleophile, with a primary alkyl halide in an SN2 reaction, followed by deprotonation of the carbon with a strong base, such as butyllithium. The carbonyl carbon and the carbon originally bonded to the halogen become the two carbons with the double bond in the product alkene X m CH3 The real value of the Wittig reaction lies in its ability to yield an alkene of predictable structure, as the C=C bond is precisely where the C=O bond was in the reactant and no isomers (other than E/Z isomers)…arrow_forwardWhich of the following statements is correct? A) The haloform reaction proceeds under very difficult conditions and the yield is very low. B) The haloform reaction is used only for the identification of compounds containing secondary alcohol groups. C) Methyl ketones or alcohols are oxidized with halogens in acidic solutions to give carboxylic acids and the appropriate haloform product. D) Enolate anions react rapidly with halogens to give alpha-halocarbonyl compounds.arrow_forward2-Ethyl-1-hexanol was needed for the synthesis of the sunscreen octyl p-methylcinnamate. Show how this alcohol could be synthesized (a) by an aldol condensation of butanal and (b) by a malonic ester synthesis starting with diethyl malonate.arrow_forward
- Write four examples of the condensation reactions of carbonyl compounds, starting with benzaldehyde (C6H5CHO), with appropriate reagents and appropriate reactions. Write down the mechanism of one you want in detail.arrow_forwardA problem often encountered in the oxidation of primary alcohols to acids is that esters are sometimes produced as by-products. For example, oxidation of ethanol yields acetic acid and ethyl acetate: Propose a mechanism to account for the formation of ethyl acetate. Take into account the reversible reaction between aldehydes and alcohols:arrow_forwardEnamines normally react with methyl iodide to give two products: one arising from alkylation at nitrogen and the second arising from alkylation at carbon. For example, Heating the mixture of C-alkylation and N-alkylation products gives only the product from C-alkylation. Propose a mechanism for this isomerization.arrow_forward
- Nonconjugated , -unsaturated ketones, such as 3-cyclohexenone, are in an acid-catalyzed equilibrium with their conjugated , -unsaturated isomers. Propose a mechanism for this isomerization.arrow_forwardThe pyrolysis of acetic esters to give an alkene and acetic acid is thought to involve a planar transition state and cyclic redistribution of (4n + 2) electrons. Propose a mechanism for pyrolysis of the following ester.arrow_forwardFollowing 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?arrow_forward
- Show how to bring about each step in this synthesis of the herbicide propranil.arrow_forwardThe compound 3,5,5-trimethyl-2-cyclohexenone can be synthesized using acetone and ethyl acetoacetate as sources of carbon atoms. New carbon-carbon bonds in this synthesis are formed by a combination of aldol reactions and Michael reactions. Show reagents and conditions by which this synthesis might be accomplished.arrow_forwardAldehydes and ketones react with thiols to yield thioacetals just as they react with alcohols to yield acetals. Predict the product of the following reaction, and propose a mechanism:arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage LearningEBK A SMALL SCALE APPROACH TO ORGANIC LChemistryISBN:9781305446021Author:LampmanPublisher:CENGAGE LEARNING - CONSIGNMENT