Ethers, geranyl synthesis

Synthesis of geranyl 6-0-fl-o-xylopyranosyl-(3-D-glucopyranoside (82) Tert-butyldimethylsilylation of 51 gave a silyl ether (84, 63% yield), which was subjected to benzoylation to give a benzoate (85) in 71% yield. Desilylation of 85... 

Many papers from the patent literature on pyrethroids and juvenile hormones cannot be included in this Report. Papers have reported the synthesis and activity of monoterpenoid juvenoids, including geranyl pyridyl ethers " and geranyl alkyl ethers and amines and their epoxides. Further papers in this section include a report of the potent lung toxicity of perillaketone, the observation that the malodorous water contaminant 2-methylisoborneol has the l-R-exo configuration, and that fenchyl methyl L-aspartylaminomalonate is 2 x 10" times sweeter than sucrose. ... 

Various approaches to the synthesis of menaquinones have been made, in which the aromatic component is activated to encourage nucleophilic attack upon a receptive prenyl fragment. Thus alkylation of the potassium salt of 2-methyl-1,4-naphthoquinol (236) or 4-methoxy-3-methyl-l-naphthol (237) with geranyl bromide (244) gave menaqui none-2 (246) in 20 and 45% yield, respectively, after oxidation. Hydrogenolysis of the dimethyl ether (238) of 1 -oxymenaquinol-2 [from... 

A method has been described for the functionalization of the isopropylidene terminus of isoprenoids. For example, geranyl benzyl ether (208) was converted into the phenyl thioether (210) by treatment with PhSCl and elimination of HCl. Oxidation and reaction with trimethyl phosphite gave the primary alcohol (209) stereospecifically in 75% overall yield. Use has been made of this procedure in the synthesis of solanesol (C45) from three C15 units.The tosyl derivative of the hydroxylated farnesol (211) reacts with the bromide (212) prepared from (213) to give the C30 product (215), the bromide (216) of which, after further reaction with (214), affords the solanesol derivative (217) and thence solanesol (205). 

Karahana ether (196), isolated from Japanese hops, is also a 1,1,2,3-tetra-methylcyclohexane derivative, and has been synthesised by Coates and Melvin by a route that they suggest may resemble the biogenetic pathway.Their synthesis consists in cyclising geranyl acetate (194) with benzoyl peroxide in the presence of cupric saltsand hydrolysing the resulting mixture to the corresponding diols, from which the cis-diol (195) is separated and converted to the ether with p-toluenesulphonyl chloride in pyridine at room temperature. 

Methoxy-3-prenyl-2-quinolones were first prepared in connection with the synthesis and biosynthesis of quinoline alkaloids (Volume IX, pp. 247, 257), but soon afterward prenyl derivatives were identified as constituents of rutaceous plants (Table I). -Prenyl and O-geranyl ethers without, substituents in the 3-position of the quinoline nucleus will be discussed in Section V of this chapter. 

The structure of bucharaine has now been confirmed by synthesis (Scheme 25). The geranyl ether 286 was prepared from 4-hydroxy-2-quinolone and geranyl chloride. Selective epoxidation with m-chloro-perbenzoic acid yielded monoepoxide 287. Reaction of the epoxide with formic acid gave the formate ester 288, which on treatment with base was converted into bucharaine (206). 

A total synthesis of ethyl geranate (28) makes use of the addition of ethyl 4-bromo-3-methylbut-2-enoate (29) to the nickel carbonyl complex (30) of prenyl bromide. Geranyl acetate and the ethyl ether were made in a similar way. ... 

In the 1980s, the Japanese firm Kuraray developed a stereoselective Vitamin A synthesis, which follows the Cm + Cm concept. The synthetic building blocks are cyclogeranyl phenyl sulfone and a Cm-aldehyde, which is obtainable by allylic oxidation of geranyl acetate with t-butyl hydroperoxide. [81] The alcohol function is protected as the THP-ether, and the sulfmic acid and hydroxytetrahydro-pyran are eliminated with potassium fbutoxide in petroleum ether. By means of this double elimination, the reduction step is avoided. 

Linalool can be converted to geranyl acetone by the Carroll reaction (156). After transesterification with ethyl acetoacetate, the intermediate ester thermally rearranges with loss of carbon dioxide. Linalool can also be converted to geranyl acetone by reaction with methyl isopropenyl ether. The linalyl isopropenyl ether rearranges to give geranyl acetone. Geranyl acetone is an important intermediate in the synthesis of isophytol [505-32-8], famesol [106-28-5], and nerolidol [40716-66-3]. Isophytol is used in the manufacture of Vitamin E and thus linalool is a key intermediate in the synthesis of the latter. All of these reactions are shown in Fig. 8.55 in the section on nerolidol. 

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