Allyl Claisen rearrangement

Allyl Claisen rearrangements of carbonate esters have already been discussed under ester rearrangement reactions (see Table 7). 

Claisen Rearrangements - allyl vinyl ether to an y,5-unsaturated carbonyl... 

You have already seen that a carbon-heteroatom bond is easy to make, since we used such bonds as natural places for disconnections (frames 234 ft). It is good strategy therefore to make a carbon-heteroatom bond and then to transform it into a carbon-earbon bond. The Claisen rearrangement is one way to do this an ortho allyl phenol (B) made from an allyl ether (A) ... 

Conjugate addition of vinyllithium or a vinyl Grignard reagent to enones and subsequent oxidation afford the 1.4-diketone 16[25]. 4-Oxopentanals are synthesized from allylic alcohols by [3,3]sigmatropic rearrangement of their vinyl ethers and subsequent oxidation of the terminal double bond. Dihydrojasmone (18) was synthesized from allyl 2-octenyl ether (17) based on Claisen rearrangement and oxidation[25] (page 26). 

Allylic Rearrangement, Claisen Rearrangement, and Related Reactions Catalyzed by Pd(0) and Pd(II)... 

Conversion of 5-allylthioimidates into /V-allylthioamides is catalyzed by Pd(Il). 2-Allylthiopyridine (820) is converted into the less stable l-allyl-2-thio-pyridone 821 owing to Pd complex formation[509], Claisen rearrangement of 2-(allylthio)pyrimidin-4-(3//)-one (822) affords the A-l-allylation product 823 as the main product rather than the A -3-allylation product 824[510] The smooth rearrangement of the allylic thionobenzoate 825 to the allyl thiolo-benzoate 826 is catalyzed by both PdCl2(PhCN)2 and Pd(Ph3P)4 by different mechanisms[511],... 

Q The mechanism of the Claisen rearrangement of other allylic ethers of phenol is analogous to that of allyl phenyl ether What is the product of the Claisen rearrangement of C6H50CH2CH CHCH3 /... 

Section 24 13 On being heated allyl aryl ethers undergo a Claisen rearrangement to form o allylphenols A cyclohexadienone formed by a concerted six tt electron reorganization is an intermediate... 

Claisen rearrangement (Section 24 13) Thermal conversion of an allyl phenyl ether to an o allyl phenol The rearrange ment proceeds via a cyclohexadienone intermediate... 

A heterocyclic ring induces partial double-bond fixation in a fused benzene ring. Hence, for example, diazo coupling occurs at the 7-position of 6-hydroxyindazole (349), and Claisen rearrangement of 6-allyloxy-2-methylbenzothiazole (350) gives the 7- and 5-allyl products in a ratio of 20 1. 

Alkylation of 3-methyl-4-phenylisoxazolin-5-one with allyl bromide gave a mixture of N- and C(4)- alkylation in a 2 1 ratio. Heating the mixture changed the ratio to 1 99 and this conversion is believed to take place by an amino-Claisen rearrangement (Scheme 91) (69TL543). 

Cartxjxylalion and subsequent allylation of alkyl heterocycles (via Claisen rearrangement of allyl esters)... 

CLAISEN - IRELAND Rearrangment Rearrangement ol allyl phenyl ethers to o (or p-)allylphenols or of allyl vinyl ethers to y.S-unsaturated aldehydes or ketones (Claisen) Rearrangement ol allyl esters as enolale anions to y.S-unsaturated acids (Ireland)... 

Compound 1, 2,2-diniethyl-4-pentenal, has been prepared by the Claisen rearrangement route described above and by reaction of isobutyraldehyde with allyl chloride in the presence of aqueous sodium hydroxide and a phase-transfer catalyst. Both routes are applicable to the synthesis of a variety of substituted 4-pentenals. 

This effect is the basis of the synthetic importance of ester enolate Claisen rearrangements in which enolates or silyl enol ethers of allylic esters are rearranged into 4-pentenoate esters. 

Claisen rearrangement of the allyl enol ether of tnfluoroacetylacetone gives a C-allylated derivative [123] (equation 106)... 

Allyl ethers of perfluoroaromatic phenols have been observed to alkylate the aromatic nucleus [106] or to undergo Claisen rearrangement [1071 (equation 54). 

A synthetically valuable reaction sequence is the chlorodifluoroacetylation of various substituted allylic alcohols and the subsequent Reformatskii-Claisen rearrangement of the ester thus formed to interesting 2,2-difluoropentenoic acid derivatives [25] (equation H) Comparable sequences have been reported for ally monofluoroacetates [26] and allyl 3,3,3-trifiuoropropanoates [27] (equations 15 and 16). 

When ethyl trifluoroacetylacetate is treated with an allylic alkoxide, tran-sesterification is followed by ester enolate Claisen rearrangement m a process that on decarboxylation yields stereospecifically the tnfluoromethyl ketone product [22] (equation 19)... 

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