Friedel-Crafts reaction carbonyl compounds

Reactions 1-22 to 1-26 involve the introduction of a CH2Z group, where Z is halogen, hydroxyl, amino, or alkyithio. They are all Friedel-Crafts reactions of aldehydes and ketones and, with respect to the carbonyl compound, additions to the C=0 double bond. They follow mechanisms discussed in Chapter 16. 

We used this strategy in chapter 6 under two-group C-X disconnections where bromination of ketones was the usual functionalisation. More relevant here are conversions of carbonyl compounds into 1,2-dicarbonyl compounds by reaction with selenium dioxide SeC>2 or by nitrosation. So acetophenone 57 gives the ketoaldehyde10 58 with SeC>2. These 1,2-dicarbonyl compounds are unstable but the crystalline hydrate 59 is stable and 58 can be reformed on heating. Since aromatic ketones such as 57 would certainly be made by a Friedel-Crafts reaction the disconnection 58a is not between the two carbonyl groups and offers an alternative strategy. 

Haworth reaction A reaction in which an aryl compound is treated with a cyclic anhydride, such as succinic anhydride, and the intermediate Friedel-Crafts product is reduced and then cyclised via an internal Friedel-Crafts reaction to give a 1,2-disubstituted aromatic compound with a carbonyl group in the new ring. The whole sequence is called the Haworth reaction. 

This alternative to the Friedel-Crafts reaction, extensively developed by Stille and coworkers, is particularly important, since the reaction conditions are essentially neutral, and so provides a method for acylation of compounds containing an acid-sensitive functionality which would preclude the use of the Friedel-Crafts reaction. Reaction temperatures are often below 100 C, and high (1000-fold) turnovers of the catalyst have been achieved. Solvents employed include chloroform, toluene, and, on occasions, HMPA. Some reactions have been carried out under an atmosphere of carbon monoxide to prevent excessive decarbonylation of the acyl palladium intermediate. Indeed, carbonylative coupling of alkenylstannanes with allyl halides in the presence of carbon monoxide ca. 3 atm or greater 1 atm =101 kPa) offers an alternative to the Friedel-Crafts acylation, ketones being formed by the reaction of the stannane with the acyl species formed by carbon monoxide insertion into the allyl palladium intermediate. ... 

Additions with Friedel-Crafts reaction Alcohols from carbonyl compounds... 

Ionic routes to allylic (2) and benzylic (4) alcohols use reduction of carbonyl compounds (1) and (3) since these are readily available by condensation or Friedel-Crafts reaction. 

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