Oxymercuration ethers from

Our solution to this synthetic problem was the development of an iterative technique for preparing hydroxypropyl ethers from allyl ethers via oxymercuration-reduction. Figure 3 illustrates the process for the preparation of a series of three chain-extended hydroxypropyl derivatives of 2,6-dimethoxyphenol. Conversion of phenol 1 to the allyl ether 2 under phase-transfer conditions (6) was followed by oxymercuration (7) to give the intermediate organomercurial 3, which was reduced without isolation to give hydroxypropyl ether 4 in 64% overall yield. Ether 4. was then allylated to provide 5, which upon oxymercuration-reduction afforded hydroxypropyl derivative 6. One further iteration of the allylation-oxymercuration-reduction sequence yielded the hydroxypropyl compound 7. 

Cyclic ethers from ethylenealcobols by oxymercuration-demercuration... 

It is believed that the regiospecifidty of the dioxabicyclization and the concurrent formation of bicyclic ethers 48 and 49 both result from equilibrium control of reversible (per)oxymercuration — de(per)oxymercuration. Thus to optimise the yield of 47 it is important to minimize the amount of water present in the reaction mixture and use of concentrated hydrogen peroxide (>80%) with anhydrous mercury(II) trifluoroacetate is recommended. 

Cyclizations are also used to create glycosidic linkages. In the example given in Scheme 4.63, the E (303) and Z (304) enol ethers were obtained from the reaction of the aldehyde 301 with the phosphonate 302 [636]. Oxymercuration-demercuration of 303 and 304 gave the (3-linked (305) and a-linked (306) KDO disaccharides, respectively. 

As a general procedure if the olefin is impure, the oxymercura-tion-reduction process may include an olefin purification step. Alternatively, this process may be used to purify the olefin for other purposes. - In such cases, acetone is substituted for ether and, after oxymercuration for the same length of time as suggested above, the solution is poured with stirring into two volumes of water containing one equivalent each of sodium bicarbonate and sodium chloride. The mercury derivative is filtered, recrystallized from ethanol-water, ether, dioxane, or ethyl acetate-heptane and then either reduced as described above (in 70-80% yield) to produce pure alcohol, or deoxy-mercurated with cold 6N HCl, with ethereal lithium aluminum hydride (added cautiously), or high concentrations of alkali halides - to produce the pure olefin. 

Esters, from diazoketones and organo-boranes, 53, 82 Esters, a-deuterio-, S3, 82 Esters, 7,6-unsaturated by Claisen rearrangement, 53,122 Ethers, by oxymercuration, 53, 96 Ethers, aryl methyl-, selective mono-demethylation of, 53, 93 Ethyl diazoacetate, as source of car-bethoxycarbene, 50, 94 Ethylenediamine, complexes with chromium(II) salts, 52, 62 Ethylene, with p-methoxyphenylacetyl chloride and aluminum chloride to give 6-methoxy-/3-tetralone,... 

Haroutounian and coworkers reported an efficient synthesis of (-f)-desoxoprosophyUine (ent-8) from furyl alcohol derivative via (2R)-hydroxymethyldihydropyridinone as a key chiral building block [30]. D-Glucal was subjected to oxymercuration and subsequent protection of the primary alcohol as tert-butyldiphenyllsilyl (TBDPS) ether to give 91. The secondary hydroxyl group of 91 was subjected to Mitsunobu inversion followed... 

Oxymercuration is the key reaction in an interesting approach to 2,6-dimethyl-18-crown-6 from diallyl ether and tetraethylene glycol (Scheme 48). Some new optically active macrocycles (90) have been prepared that use as the chiral... 

Routes to cyclonona-2,3- and -3,4-dienols from related 9,9-dibromobicyclo-[6,1,0]nonanes and alkyl-lithium are reported/ and cyclodeca-2,3-dienol is obtained similarly from 10,10-dibromobicyclo[7,l,0]decan-2-ol. Oxymercuration of cyclonona-l,2,6-triene with mercuric chloride in ethanol followed by reduction gives the expected cis,cis-cyclonona-2,6-dienyl ethyl ether, but cyclodeca-l,2,5,8-tetraene gives largely (164) and (165) on reaction with mercuric sulphate in acetic acid the carbenoid (166) is implicated. ... 

---