Carrol rearrangement

Asymmetric decarboxylative rearrangement (Carroll rearrangement) of allyl a-acetamido-/3-ketocarboxylates, catalysed by a palladium complex modified with a chiral phosphine ligand, has been reported to give optically active /,5-unsaturated a-amino ketones with up to 90% ee (Scheme 92).135 The mechanism for the Carroll rearrangement is shown in Scheme 93. 

In an imioortant industrial process, the Carroll reaction , an ahphatic version of the Claisen rearrangement occurs. See if you can find the right mechanism ... 

The rearrangements of various allylic compounds catalyzed by both Pd(II) and Pd(0) are treated in this section[491]. Related reactions such as the Carroll rearrangement are treated in Section 2.10.1 and the Pd(II)-catalyzed Cope rearrangement is treated in Chapter 5, Section 3. 

Claisen and Carroll rearrangements of hydroxyalkenylsilanes provide an asymmetric synthesis of allylsilanes from optically active secondary alcohols39,40. 

The Claisen rearrangement, discovered in 1912, has proven to be a powerful tool for the stereoselective generation of C—C bonds69. It is widely employed in complex multistep syntheses (see, for example, References 86-89) and has inspired many variations, including the Carroll (1940), Eschenmoser (1964), Johnson (1970), Ireland (1972) and Reformatsky-Claisen (1973) reactions69. 

However, if only two carbon atoms are present (15) they may be disconnected to give an allylic alcohol 16 and the acetoacetic ester, through a retro-Carroll rearrangement [6] (Scheme 7.6). 

The method of preparation of 5-dodecen-2-one presented here is a version of the literature procedure published earlier. It offers several advantages over existing methodology (1) The ester enolate modification of the Carroll rearrangement provides the allylic acetoacetates via a mild, fast, and high yield synthesis. This procedure represents a significant Improvement over... 

The Carroll Rearrangement Synthesis of 5-Dodecen-2-one S. R. Wilson and C. E. Augelli, Department of Chemistry,... 

Addition of acetylene to acetone results in the formation of 2-methyl-3-butyn-2-ol, which is hydrogenated to 2-methyl-3-buten-2-ol in the presence of a palladium catalyst. This product is converted into its acetoacetate derivative with diketene [38] or with ethyl acetoacetate [39]. The acetoacetate undergoes rearrangement when heated (Carroll reaction) to give 6-methyl-5-hepten-2-one ... 

Linalool can be converted to geranyl acetone (63) by the Carroll reaction (34). By transesterification with ethyl acetoacetate, the intermediate ester thermally rearranges with loss of carbon dioxide. Linalool can also be converted to geranyl acetone by reaction with methyl isopropen ether. The linalyl isopropenyl ether rearranges to give the geranyl acetone. 

The Carroll rearrangement, a variation on the ester Claisen rearrangement, is a useful method for the preparation of y, 8-unsaturated ketones from allyl acetoacetates, and has been adapted to provide a method for the synthesis of a number of specific arylacetones. Thus, treatment of the p-quinol 1 with diketene and a catalytic amount of DMAP at room temperature gave a 72% yield of the arylacetone 2 together with 5% of the benzofuran 3. 

Kubagawa, H., Cooper, M.D., Carroll, A.J., Burrows, P.D. (1989). Light-chain gene expression before heavy-chain gene rearrangement in pre-B cells transformed by Epstein-Barr virus. Proc. Natl. Acad. Sci. USA 86, 2356-2360. 

The reductive coupling of the 7i-allylpalladium enolates 400 gives the allylated ketones 403. This reaction is also possible thermally and is called the Carroll reaction. Whereas the Carroll reaction proceeds by heating up to 200 °C, the Pd-catalysed Carroll-type reaction can be carried out under mild conditions (even at room temperature) by reductive elimination of the 7t-allylpalladium enolate 400 [177,178], The Pd-catalysed reaction is mechanistically different from the thermal reaction and more versatile, which is explained by the [3,3] sigmatropic rearrangement of the enolate form. For example, thermal Carroll rearrangement of the a,a-disubstituted keto ester 410 is not possible, because there is no possibility of the enolization. However, it rearranges to ketone 411 smoothly with the Pd catalyst, via the 7i-allylpalladium enolate. 

Carroll, G.L., Harrison, R., Gerken, J.B., and Little, R.D. (2003) Coping with substituent effects in divinylcydopropyl dizaene rearrangements. Tetrahedron Letters, 44, 2109-2112. 

This reaction based on the petrochemical crude material isobutylene makes the synthetic route to P-ionone (36) substantially shorter and cheaper, especially since the isomeric double bond proves to be advantageous in the subsequent reactions. In addition, i-methylheptenone (37 a) can be converted into methylheptenone (37) by noble metal-catalyzed isomerization. The reaction steps ethynylation (C2 addition), Carroll reaction (C3 addition), ethynylation and partial hydrogenation (C2 addition) lead from methylheptenone (37) via dehydrolinalool (42), pseudoionone (43) and p-ionone (36) to the C15 alcohol p-vinylionol (44). With triphenylphosphine (15), the desired C15 phosphonium salt (13), which is the second important synthetic building block for vitamin A and carotenoids16), is obtained directly from p-vinylionol, by allyl rearrangement. 

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