Dolbier HW Solutions 472

Dolbier HW Solutions 472 - 566 CARBOXYLIC ACID DERIVATIVES:...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 566 CARBOXYLIC ACID DERIVATIVES: NUCLEOPHILIC ACYL SUBSTITUTION Step 6 is ester saponification. It yields a 16-carbon chain having a carboxylic acid function at one end and an alcohol at the other. Step 6: O Compound F 1. KOH, ethanol HOC(CH2)5CH 2. H CH(CH2)7CH2OH Compound G (C16H30O3) In step 7, compound G cyclizes to ambrettolide on heating. Step 7: heat HO2C HO O O Compound G 20.35 (a) Ambrettolide This step requires the oxidation of a primary alcohol to an aldehyde. As reported in the literature, pyridinium dichromate in dichloromethane was used to give the desired aldehyde in 84% yield. O HOCH2CH PDC CH2Cl2 CH(CH2)7CO2CH3 HCCH Compound A CH(CH2)7CO2CH3 Compound B O (b) CH Conversion of appropriate. to @ CH ? CH2 is a typical case in which a Wittig reaction is O HCCH CH(CH2)7CO2CH3 (C6H5)3P CH2 H2C Compound B (c) CH(CH2)7CO2CH3 Compound C (observed yield, 53%) Lithium aluminum hydride was used to reduce the ester to a primary alcohol in 81% yield. H2C CHCH CH(CH2)7CO2CH3 1. LiAlH4 2. H2O H2C Compound C (d ) CHCH CHCH CH(CH2)7CH2OH Compound D The desired sex pheromone is the acetate ester of compound D. Compound D was treated with acetic anhydride to give the acetate ester in 99% yield. OO H2C CHCH CH(CH2)7CH2OH CH3COCCH3 pyridine Compound D O H2C CHCH CH(CH2)7CH2OCCH3 (E )-9,11-Dodecadien-1-yl acetate Acetyl chloride could have been used in this step instead of acetic anhydride. 20.36 Back Forward (a) The reaction given in the problem is between a lactone (cyclic ester) and a difunctional Grignard reagent. Esters usually react with 2 moles of a Grignard reagent; in this instance Main Menu TOC Study Guide TOC Student OLC MHHE Website ...
View Full Document

Ask a homework question - tutors are online