Ethers propargyl vinyl, Claisen rearrangement

The Claisen rearrangement of propargyl vinyl ethers directly delivers the allene no equilibrium is observed. This reaction was also successful with complex substrates in order to show this, of numerous examples [375, 513-536], the compounds 159 [537] and 161 [538] are depicted (Scheme 1.71). 

Thermal propargyl rearrangement-Claisen rearrangement of propargyl vinyl ethers and Cope-type rearrangements of propargyl malonates [93]. 

Dihydro-2-hydroxypyrans are formed from propargyl vinyl ethers in a Au(I)-catalysed Claisen rearrangement - heterocyclisation sequence in wet dioxane. Stereochemical features in the substrate are retained in the product. Incorporation of an alkanol function adjacent to the O atom results in the formation of spiroketals (Scheme 3) <06JA8132>. [3-Hydroxyallenes... 

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-... 

Au-Catalyzed reaction of propargyl vinyl ethers furnished tri- and tetrasubstituted furans in high yields. The reaction proceeded through cyclization of 2-allenyl-13-dicarbonyl intermediates produced from propargyl-Claisen rearrangement <05OL3925>. 

For the design of organometallic catalytic reactions, one can apply stereoelectronic effects that are specific to the metal centers, such as the trans-effect. An interesting manifestation of this effect in the Rh-catalyzed Claisen rearrangement of propargyl vinyl ethers (Figure 11.13) was found in the computational analysis of this process. ... 

Figure 11.14 Energy profile of the Rh-catalyzed Claisen rearrangement of propargyl vinyl ethers initiated by coordination at the alkyne. Red and gray depict the cis and the trans orientations, respectively, of CO relative to substrate at the Rh center. Energies were calculated relative to the most stable Rh(l)-vinyl ether complex at the M05-2X/LANL2DZ level.

We attempted the synthesis of 1,2-dihydropyridines from propargyl vinyl ethers in an independent study (11JOC2145). In our early experiments, we studied propargyl vinyl ethers 79 with additional alkyl substituents at the vinylic position. The propargyl Claisen rearrangement was effected by catalytic amounts of silver(I) hexafluoroantimonate, and the addition of an amine to the aUenylcarbonyl intermediate was expected to provide the 1,2-dihydropyridine product 80. Unfortunately, the major product was, in aU cases, the 2ff-pyran 81, and the desired dihydropyridine 80 was only formed in yields ranging from 10% to 44% when aniline derivatives were employed (Scheme 27).With aliphatic amines, the formation of 1,2-dihydropyridines was not observed. 

Representative procedure for the gold-catalyzed Claisen rearrangement of propargyl vinyl ethers. (R)-3-(2-Phenylvinylidene)heptan-l-of ... 

The related Gosteli-Claisen rearrangement of 2-alkoxycarbonyl-substituted propargyl vinyl ethers can also be catalyzed by cationic gold(I) complexes and provides highly substituted furan derivatives. ... 

Alkoxycarbonyl-substituted propargyl vinyl ethers have been reported to undergo GosteU-Claisen rearrangement (Scheme 5). ... 

In a convenient one-pot process, easily accessed propargyl vinyl ethers and aromatic amines are effectively converted into tetra- and pentasubstituted 5-methylpyrroles, which can fnrther be transformed into 5-formylpyrroles via 2-iodoxybenzoic acid (IBX)-mediated oxidation (Binder and Kirsch 2006). The cascade reaction proceeds through a silver(l)-catalyzed propargyl Claisen rearrangement, an amine condensation, and a gold(l)-catalyzed 5-exo-dig heterocyclization, as shown in Schane 11.4. 

Kirsch has reported the conversion of propargyl vinyl ethers to form pyrroles via a multi-step transformation involving the silver-catalyzed propargyl Claisen rearrangement to form the a-allenyl P-keto ester, condensation with a primary aryl amine. 

Scheme 10.24 Propargyl vinyl ether Claisen rearrangement.

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