Alkenyl allyl ethers

Not only an aryl group—as in Figure 14.46—but also an alkenyl group can participate in the Claisen rearrangement of allyl ethers (Figure 14.47). Allyl enol ethers are the substrates in this case. Figure 14.47 shows how this kind of allyl alkenyl ether (D) can be prepared from an... 

An interesting new feature was found in the reaction of the enol ether 131 under Heck-type conditions. In the presence of both [PdCPPhj) and base, the allyl alkenyl ether 131 undergoes a Pd -catalyzed 1,3-allyl shift and an intramolecular Heck arylation to give the spiroindane 132 (Scheme 3-35). Mechanistic investigations suggest that the 1,3-allyl shift proceeds via a jr-allylpalladium intermediate 133 [186]. 

Perfluoroallyl fluorosulfate is prepared by the treatment oiperfluoropropene with sulfur tnoxide m the presence of boron catalysts [2, 3, 4, 5, 6, 7] (equation 2) Perfluoroisopropyl allyl ether reacts similarly to give 58% polyfluoroallyl fluorosulfate in a cis/trans ratio of 6 4 [S] Sultones are the exclusive products without catalyst. Polyfluoroolefins such as 2-hydropentafluoropropylene [9], (2,3-dichloropropyl)tri-fluoroethylene [70], perfluoropropene [2, i], perfluoroisopropyl alkenyl ethers [S], and acyclic polyfluoroallyl ethers [77] undergo sulfur trioxidation to regioselectively produce the corresponding P-sultones in high yield... 

Metallated allylic ethers can also be used as partners in allylzincations of alkenyl-metals144. Allyl methyl ether could be metallated with s-BuLi in ether provided that TMEDA was present and, after transmetallation with ZnBr2, addition to the alkenyl-lithium derived from 205 proceeded slowly at room temperature. Nevertheless, after hydrolysis the corresponding allylic ether 227 was obtained with high diastereoselectivity (equation 110)146. 

The nature of the oxidation products is traceable to the nature of the rhodium-alkene interaction. Terminal alkenes and internal ones (e.g. cycloheptene), which form 77-complexes of rhodium(I), e.g. [RhCl(alkene)2]2, are selectively converted into methyl ketones, whereas alkenes which form 7r-allylic complexes of rhodium(III) (e.g. cyclopen-tene) give alkenyl ethers via oxidative substitution of the alkene by the solvent alcohol.204... 

A mercury-free route to allyl vinyl ethers that relies on the Michael addition of allyl alcohols to unsubstituted alkenyl sulfoxides, followed by thermal loss of sulfenic acid and concurrent Claisen rearrangement has been described [145]. This methodology has been applied to the synthesis of isocar-bacyclin [146]. Posner reported an acid-catalyzed protocol that produces conjugated dienoate esters from allylic alcohols and a sulfinyl orthoester [147]. Additionally, the use of propargyl alcoholates and a chloro alkenyl sulfox-... 

Isomerization. Allyl ethers and allyl acetals undergo isomerization to furnish the (Z)-alkenyl ethers with (dppblNiClj-LiBHEtj." On the other hand, the isomerization mediated by (PhjPljRuClj-LiBHEtj is almost totally stereorandom. 

Upon treatment with BFj OEt2, stannane 265 is isomerized via an inter-molecular pathway, resulting in allylic transposition and stereochemical inversion of configuration to yield 266 (Scheme 5.2.57, bottom), and this process provides an efficient route to non-racemic y-(alkoxy)allylic stannanes. The reaction of stannane 267 is advanced with unsaturated aldehydes and achieves facial selectivity by the antiS mechanism giving mainly the syn product 268, containing an E-alkenyl ether. The anti-SE arrangement shown in 270 minimizes non-bonded interactions leading to the major product. Similarly, the chiral stannane 271 adds to aliphatic aldehydes to produce the E-iyn-alcohol 272 (Scheme 5.2.58). ... 

Alkyl-(3-hydroxy-l-alkenyl)-ether sind besonders saurelabil, weil sie sich iiber ein reso-nanzstabilisiertes Allyl-Kation leicht in Halbacetale umlagern dies geschieht bei der sau-ren Aufarbeitung oder bei der Chromatographie an Kieselgel ... 

Simple alkyl and alkenyl ethers of pentaerythritol are produced on direct reaction of the polyol and the required alkyl or alkenyl chloride in the presence of quaternary alkyl amine bromide (44). Allyl chloride produces the pentaerythritol tetrallyl ether [1471-18-7],... 

D.i. Allyl-Vinyl Ether Rearrangements. This reaction predated the Cope rearrangement and is obviously very similar. An alkenyl carbonyl product is obtained just as in the oxy-Cope rearrangement, but the carbonyl is generated directly rather than via initial enol formation. As with the Cope rearrangement, the... 

This chapter will discuss 1,3-dienes in a reaction with alkenes to give cyclohexene derivatives. This is a thermal reaction driven by interactions of molecular orbitals rather than ionic or polarized intermediates. In addition to the reaction of 1,3-dienes, 1,5-dienes undergo a rearrangement to a different 1,5-diene in what is known as a sigmatropic rearrangement. Similarly, allyl vinyl ethers rearrange to form alkenyl aldehydes or ketones. Both of these reactions tend to give difunctional molecules as products. 

The Claisen rearrangement of allyl vinyl ether leads to an alkenyl aldehyde. Draw both the starting material and the product. Discuss spectroscopic differences in these two molecules that will allow you to determine whether or not the reaction worked. 

Show how to synthesize allyl phenyl ether and 2-butenyl phenyl ether from phenol and appropriate alkenyl halides. 

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