Decarboxylative Claisen rearrangement

The decarboxylative Claisen rearrangement of allylic tosylacetate (5) and methyl tosylmalonate derivatives has been extensively studied. In the tosylacetate series, it has been found that acetate ions, base and a silylating agent, preferably N,0-bis(trimethylsilyl)acetamide (BSA), are all necessary, but in only catalytic quantities provided that BSA is used. Potassium acetate has been shown to be a suitable base. 

Bourgeois, D., Craig, D., King, N.P., and Mountford, D.M. 2005. Synthesis of homoallyhc sulfones through a decarboxylative Claisen rearrangement reaction. Angewandte Chemie International Edition, 44 618-21. 

Craig, D. and Grellepois, F. 2005. Decarboxylative Claisen rearrangement reactions of allylic tosylmalonate esters. Organic Letters, 7 463-65. 

Decarboxylative Claisen rearrangement of furfuryl alcohol esters can be used to introduce 3-substitutents comparable rearrangements take place with 2-thienyl and 2-pyrrolyl esters. ... 

Scheme 13.17 Decarboxylative Claisen rearrangement of a myrtenol derivative.

Scheme 13.20 Decarboxylative Claisen rearrangement of allyl 2-tosylmalonates.

Scheme 13.22 Contrasting reactivity in decarboxylative Claisen rearrangements.

Scheme 13.23 Double decarboxylative Claisen rearrangements of bisrallylici 2-tosylmalonates.

Scheme 13.33 Decarboxylative Claisen rearrangement in the synthesis of cananodine.

Scheme 13.34 General annulated pyridine synthetic strategy using the decarboxylative Claisen rearrangement.

In Scheme 13.17. decarboxylative Claisen rearrangement (dCr) reaction of myrtenyl tosylacetate 19 is shown. The sole product obtained for this tandem transformation was that of delivery of the ketene acetal to the allylic double bond in a sense anti to the more sterically demanding dimethyl-substituted methano bridge. Subsequent decarboxylation in situ gave the homoallylic sulfone 20. This reaction gave similar yields when carried out under microwave conditions. 

Microwave-assisted double decarboxylative Claisen rearrangement of bis(allyl) 2-tosylmalonates to substituted 1,6-heptadienes was studied. These heptadienes may be alkylated, and then converted into pyridines by ozonolysis followed by reaction with ammonia generated in situ under microwave conditions (Craig et al., 2008). 

Microwave-assisted decarboxylative Claisen rearrangement reactions of substituted acetate derivatives of 3-(hydroxyalkyl)indoles give dearomatised products (Camp et al., 2011). The reactivity of the resultant compounds was evaluated. 

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