Tunicates are marine animals that are called "sea squirts" because when they are taken out of water, they tend to contract and expel seawater. Lepadiformine is a cytotoxic agent (toxic to cells) isolated from a marine tunicate. During a recent synthesis of lepadiformine, the investigators observed the formation of an interesting by-product (3) while treating diol 1 with a reagent similar in function to PBr3 (J. Org. Chem. 2012, 77, 3390-3400): Но, R dibromide + PBr3 R ÕH 1 2 3 Modify the given structure to draw a structure for the desired product (2). Но OH Edit Drawing

Tunicates are marine animals that are called "sea squirts" because when they are taken out of water, they tend to contract and expel seawater. Lepadiformine is a cytotoxic agent (toxic to cells) isolated from a marine tunicate. During a recent synthesis of lepadiformine, the investigators observed the formation of an interesting by-product (3) while treating diol 1 with a reagent similar in function to PBr3 (J. Org. Chem. 2012, 77, 3390-3400): Но, R dibromide + PBr3 R ÕH 1 2 3 Modify the given structure to draw a structure for the desired product (2). Но OH Edit Drawing

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter22: Carbonyl Alpha-substitution Reactions

Section22.SE: Something Extra

Problem 63AP: As far back as the 16th century, South American Incas chewed the leaves of the coca bush,...

See similar textbooks

Similar questions

What is the structural requirement for a substance to react with ammoniacal AgNO3? Why would acetylene react with Tollen's reagent but not cyclohexane or cyclohexene?
Some alcohols undergo rearrangement or other unwanted side reactions when they dehydrate in acid. Alcohols may be dehydrated under mildly basic conditions using phosphorus oxychloride (POCl3) in pyridine. The alcohol reacts with phosphorus oxychloride much like it reacts with tosyl chloride, displacing a chloride ion from phosphorus to give an alkyl dichlorophosphate ester. The dichlorophosphate group is an outstanding leaving group. Pyridine reacts as a base with the dichlorophosphate ester to give an E2 elimination. Propose a mechanism for the dehydration of cyclohexanol by POCl3 in pyridine.
(a) Tsomane and Nyiko were given a task of synthesising methylenecyclohexane 2. After a brief discussion with each other, Tsomane proposed Method A to synthesise 2 from cyclohexanone 1 while Nyiko proposed Method B that started from hydroxymethylcyclohexane 3. Each student believed that their proposed method is better than the other. (Scheme below) (1) Ph Ph 8*8 Ph THF A 1 Santande B H₂SO4 100 °C 3 OH Using curly arrows, provide full mechanistic details accounting how methylenecyclohexane 2 was synthesised according to both Methods A and B.
3. Isoerythrogenic acid, C18H26O2, is an acetylenic fatty acid that turns a vivid blue on exposure to UV light. On Catalytic hydrogenation over a palladium catalyst, five molar equivalents of hydrogen are absorbed, and stearic acid, CH3(CH2)16CO2H, is produced. Ozonolysis of isoerythrogenic acid yields the following products: formaldehyde, CH2O, malonic acid, HO2CCH2CO2H, adipic acid, HO2C(CH2)4CO2H, and the aldehyde carboxylic acid, OHC(CH2)6CO2H. Provide a structure for isoerythrogenic acid.
(a) Tsomane and Nyiko were given a task of synthesising methylenecyclohexane 2. After a brief discussion with each other, Tsomane proposed Method A to synthesise 2 from cyclohexanone 1 while Nyiko proposed Method B that started from hydroxymethylcyclohexane 3. Each student believed that their proposed method is better than the other. (Scheme below) (1) 1 Ph THF A Ph Ph B H₂SO4 100 °C 3 OH What is the name of the reaction that is followed by reaction Method A?
Grignard reagent is a versatile tool in synthetic organic chemistry. Using bromocyclopentane as a starting material, show how a Grignard reagent, X, is synthesized. Reaction of X with water produces compound Y while treatment in carbon dioxide followed by hydrolysis forms compound Z. 3-methyl-2butanone reacts with X and hydrolyses to yield compound AA. Draw the structural formulae of compounds Y, Z and AA and write the chemical equations respectively.
8. An optically active alcohol, A, C,H10O reacts with concentrated H2SO4 at 180 °C to form compound B which can exist as cis-trans isomers. Compond A reacts with hot acidified KMNO4 to produce compound C which can reacts dinitrophenylhydrazine but does not react with Tollen's reagent. The reaction between C and Grignard reagent D yields compound E upon hydrolysis. The with 2,4 structural formula for E is as follows: OH H3C-CH2-C-CH3 H3C-C-CH3 Determine the structure A, B, C and D with appropriate reason.
CH3 Ph3P-CHCH3 H3C 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. Ph3P-CHCH3 H3C The ylide is formed by reaction of triphenylphosphine, a good nucleophile, with a primary alkyl halide in an S 2 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 :0: CH3 Com 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…
A chemist wanted to synthesize the anesthetic 2-ethoxy-2-methylpropane. He used ethoxide ion and 2-chloro-2-methylpropane for his synthesis and ended up with no ether. What was the product of his synthesis? What reagents should he have used?
22. Explain why the following compound cannot be converted to a Grignard reagent. How would you resolve this problem? O & Br O A dimer would form; treat C=0 with diol in acid Mg would react with C=0; treat C=0 with diol in acid A dimer would form; treat Br with diol in acid O Mg would react with C=0; treat Br with diol in acid MgBr
In an experiment, triphenylmethanol is prepared using the Grignard reaction. The Grignard reaction involves preparation and reaction of a very nucleophilic organo-magnesium compound. The Grignard reagent is very reactive and is easily destroyed by reaction with atmospheric water, oxygen, or carbon dioxide. The Grignard reagent must be prepared under strict anhydrous conditions (dry glassware, dry solvent). The volative solvent, diethyl ether, helps to prevent oxygen or carbon dioxide from entering the reaction vessel. Reaction of bromobenzene with magnesium in ether produces phenylmagnesium bromide. This Grignard reagent then reacts with methyl benzoate to produce the corresponding alkoxide. Reaction of the alkoxide with aqueous acid then produces the alcohol. Why is it unwise to begin addition of the solution of carbonyl compound to the Grignard reagent before the latter has cooled to room temperature?
In an experiment, triphenylmethanol is prepared using the Grignard reaction. The Grignard reaction involves preparation and reaction of a very nucleophilic organo-magnesium compound. The Grignard reagent is very reactive and is easily destroyed by reaction with atmospheric water, oxygen, or carbon dioxide. The Grignard reagent must be prepared under strict anhydrous conditions (dry glassware, dry solvent). The volative solvent, diethyl ether, helps to prevent oxygen or carbon dioxide from entering the reaction vessel. Reaction of bromobenzene with magnesium in ether produces phenylmagnesium bromide. This Grignard reagent then reacts with methyl benzoate to produce the corresponding alkoxide. Reaction of the alkoxide with aqueous acid then produces the alcohol. Why does pressure develop when the separatory funnel containing aqueous sulfuric acid and the ethereal solution of organic products is shaken?