Allyl alcohol, esterification with

Dehydration and reduction of the resulting cyclohexenone under Luche s conditions gave the corresponding allylic alcohol. Esterification with an acid representing the C39 to C26 part of rapamycin gave compound 389. Finally, Ireland-Claisen rearrangement gave the branched-chain cyclohexane 390. 

Matsushima and Kino [544] have obtained the enantiomer of 429 applying AD-mix-)3-cat-alyzed dihydroxyiation of 427. Selective monosilylaltion with (f-Bu)Me2SiCl affords 438 (93% ee). After esterification of the allylic alcohol 438 with para-nitrobenzenesulfonyl chloride and subsequent sulfonate displacement with NaN3 (Sn2) azide 439 is isolated in... 

Epoxidation of the simplest allylic alcohol, allyl alcohol 7, is achieved in 88-92% ee with yields of 50-60% using diisopropyl tartrate as ligand. In situ derivatization of the product glycidol 8 via esterification, sulfonylation, or ring opening with nucleophile is an attractive alternative to isolating glycidol. 

Various aldehydes 184 and alcohols have been shown to be competent in the redox esterification of unsaturated aldehydes in the presence of the achiral mesityl triazo-lium pre-catalyst 186. Both aromatic and aliphatic enals participate in yields up to 99% (Table 13). Tri-substituted enals work well (entry 3), as do enals with additional olefins present in the substrate (entries 4 and 7). The nucleophile scope includes primary and secondary alcohols as well as phenols and allylic alcohols. Intramolecular esterification may also occur with the formation of a bicyclic lactone (entry 8). 

C12H20O2, Mr 196.29, bpo.nkPa. 91 °C, has not yet been found in nature. It is a colorless liquid with a sweet-fruity odor, reminiscent of pineapples. The ester is prepared by esterification of 3-cyclohexylpropionic acid (obtained by hydrogenation of cinnamic acid) with allyl alcohol. It is used in perfumery to obtain fruity top notes as well as pineapple and chamomile nuances. 

In contrast, allyl methacrylate is produced by the esterification of methacrylic acid and allyl alcohol (13), or by the transesterification of allyl alcohol with an ester of methacrylic acid, preferably with methyl methacrylate. The latter reaction is catalyzed with zirconium acetylacetonate (14). The esterification reactions are shown in Figure... 

Esters of allyl alcohol, e.g., diallyl phthalate, are used as bifunctional polymerization monomers and can be prepared by simple esterification of phthalic anhydride with allyl alcohol. Several acrylic esters, such as ethyl or methyl acrylates, are also widely used and can be made from acrylic acid and the appropriate alcohol. The esters are more volatile than the corresponding acids. 

The common nonenolide core of ascidiatrienolide and the didemnilactones has been formed as shown in Scheme 5 (22). Specifically, a tin-mediated, ultrasound-promoted addition of allyl bromide to unprotected glyceraldehyde 37 furnished a mixture of the corresponding homoallyl alcohols 38 which were subjected to acetalization and esterification with 5-hexenoic acid under standard conditions. At that stage, the major jy/i-isomer 40 can be purified by flash chromatography. Exposure of this diene to a refluxing solution of the ruthenium... 

Esterification—Continued by azeotropic distillation with benzene, 22, 38 by nitric acid, 22, 65 of desoxycholic acid, 24, 41 of lactic acid, 26, 4 of linoleic acid, 22, 77 of linolenic acid, 22, 83 of pyruvic acid with use of methyl ester column, 24, 72 Ester interchange, 26, 5, 19 between polylactic acid and allyl alcohol, 26, 5... 

MetalUuion ofl-dehydrocholesterol. Although 7-dehydrocholesterol has three different allylic positions, deprotonation of the potassium alcoholate 1 with this base followed by carboxylation and subsequent esterification results in the diastereomeric esters 2 as the major products. On equilibration of the mixture, the major isomer (probably the 3-isomer)... 

Allyl esters are synthesized by the azeotropic esterification of amino acids with allyl alcohol in the presence of TosOH or by reaction of N -protected amino acid cesium salts with allyl bromide.P °l They are also available from N -protected amino acids by treatment with allyl alcohol/DCC in or with diallyl dicarbonate in THF with DMAP as cat-... 

H-Ala-OAl TosOH Typical Procedure for Esterification with Allyl Alcohol/TosOHtP ... 

In its simplest version (Scheme 11.42), an allylic alcohol like 177 is treated under Eschenmoser conditions to give, with retention of configuration, the acetamide 176. Similarly, esterification to 178 and subsequent enolization to 179 sets up the Claisen conversion to 180. 

However, a source of the non-natural 9S isomer (2) was first required. The ready availability of natural crinitol made a racemization/resolution route, as illustrated in Scheme 1, attractive. Racemization was accomplished by Collins oxidation (16,25) to the dicarbonyl compound (14), followed by lithium aluminum hydride (LAH) reduction to give the racemic mixture (1 + 2). Resolution via diastereomeric derivatives seemed plausible. Esterification with enantiomerically pure a-methoxy-a-(trifluoromethyl) phenylacetic acid (MTPA) (17), followed by separation of diastereomers by recycle-HPLC (R-HPLC), had earlier been used to purify enantiomers of ipsenol and ipsdienol (26). A model system, the resolution of -3-nonen-2-ol, a secondary allylic alcohol naturally occurring in Rooibos tea (16,27), also worked satisfactorily. Therefore, the route using the bis-(MTPA) esters was selected for crinitol. 

It will be observed that, oi all the alcohols studied, methyl shows the greatest initial rate of esterification and the highest limit. The primary alcohols, ethyl, propyl, and butyl, have approximately the same initial rates and limits but are inferior to methyl alcohol in both of these respects. Allyl alcohol is much slower than propyl, the saturated alcohol with the... 

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