Allylic glycolate esters

Claisen rearrangement of glycolates. Two laboratories 2 have reported that allylic glycolate esters undergo Claisen-Ireland rearrangement (6, 276-277) with useful diastereoselectivity. This rearrangement was used in a synthesis of 1, the aggregation pheromone of the European elm bark beetle.1... 

In comparison to glycolate esters derived from primary allylic alcohols, esters with a secondary allylic alcohol moiety give enhanced selectivities (Table 13, entries 7-13). The increase in the diastereoselectivity has been attributed to the greater steric demand thus favoring the chairlike transition state. 

A soln. of 1-hexene in 4 1 acetic acid/anhydride containing NaCl (partially dissolved) and catalytic amounts of PdCl2 and CuCl2 heated at 80° for 24 h under ca. 2/1 v/v of CO and O2 acetic p-acetoxyheptanoic anhydride. Y 84%. Functionalized ethylene derivs., e.g. allyl and vinyl acetate, gave the corresponding glycol ester derivs., while 2-ethylenealcohols in ethanol afforded p,Y-dialkoxycarboxylic acid esters. F.e.s. H. Urata et al.. Tetrahedron Letters 29, 4435-6 (1988). 

A novel synthesis of (+)-avenaciolide (341) centres on the stereospecific elaboration of the anti-ester (339) by an enolate Claisen rearrangement of the corresponding ( Z)-allylic glycolate and a highly stereoselective selenolactonization of the derived... 

In contrast to the extensive use of glycolate esters, lactate, mandelate and other higher a-oxygenated esters have been used much less frequently. Early work by Bartlett et al. showed that the Ireland-Claisen rearrangement could be used to prepare allylated lactic acids in good yield, but the diastereoselectivity was disappointingly low (Scheme 4.75) [20]. 

The specificity of pectinesterase is not so marked with respect to the alcohol moiety of the ester, as it hydrolyzes ethyl esters of D-galacturonans at a rate 6-16% that of de-esterification of the methyl esters.36 Citrus natsudaidai pectinesterase de-esterifies the ethyl esters of pectic acid at a rate l/5th to l/7th of that for the methyl esters the propyl and allyl esters are attacked at l/20th to l/80th of the rate.38 The tomato, citrus, alfalfa, and papaya pectinesterases do not hydrolyze the glycol and glycerol esters of pectin.39... 

Quite recently, Tiecco [46a, 128] reported the asymmetric version of the one-pot conversion of, y-unsaturated esters and nitriles 261 (Scheme 42) into the enantiomerically enriched allylic ethers and alcohols 276 (Scheme 45). The reactions were effected with the selenenyl sulfate produced from the camphor diselenide 26. Unfortunately, in the present case, this diselenide must be employed in stoichiometric amounts. However, it can be partially recovered at the end of the reaction. Good chemical yields and enantiomeric excesses (up to 86%) were obtained in the methoxyselenenylation-elimination reactions. Lower ee was observed when the reactions were run in ethylene glycol or in water. In the case of the hydroxyselenenylations, reaction yields were low because the addition products 275 gave rise to the lactones, which were then deselenenylated to the butenolides. These were isolated in about 30% yield. 

Acrylates Acrylonitriles Allyl Esters Cellulose esters Epoxies Ethylenic (unsaturated) hydrocarbons Poly-hydroxy esters(eg Pentaerythritol tetramethacrylate,Ethylene Glycol diacrylate) Polyolefins Vinyl compound esters, acids)... 

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