Ethers, geranyl

Of the 10 constituents which represent nearly half the oil of neroH, only linalool (10) can be said to contribute direcdy to the characteristic aroma of orange flower oil. In 1977, IFF chemists performed an in-depth analysis of this oil and identified three simple terpenic compounds, each present at less than 0.01%, a-terpenyl methyl ether [1457-68-0] (31), geranyl methyl ether [2565-82-4] (32), andhnalyl methyl ether [60763-44-2] (33) (11). The latter two compounds possess green floral-citms aromas and have been known to perfumery for some time a-terpenyl methyl ether (31) has been called the orange flower ether by IFF chemists owing to its characteristic odor. 

Linalool can be converted to geranyl acetone (63) by the CarroU reaction (34). By 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 the geranyl acetone. 

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... 

For substituted allylic systems, both a- and y-substitution can occur. Reaction conditions can influence the a- versus "/-selectivity. For example, the reaction of geranyl acetate with several butylcopper reagents was explored. Essentially complete a- or y-selectivity could be achieved by modification of conditions.28 In ether both CuCN and Cul led to preferential "/-substitution, whereas a-substitution was favored for all anions in THF. 

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. ... 

Ylang-ylang Cananga odorata Hook, f et Thoms. Benzyl acetate (6-18), geranyl acetate (3-14), p-cresyl methyl ether (15-16), methyl benzoate (4-9)... 

Essential oil at the middle stage of maturity constituted monoterpene alcohols (76.77%), ketones (3.43%), esters (2.85%) and ethers (1.87%). Major constituents at this stage were linalool (76.3%), cis-dihydro carvone (3.21%),geranyl acetate (2.85%) and anethole (1.41%). Essential oils of mature fruit (final stage) were predominated by monoterpene alcohols (88.5%) and ketones... 

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). 

Polyprenylation of quinones. Trimethylstannyllithium converts polyprenyl halides (e.g., geranyl chloride, phytyl chloride) into polyprenyltrimethylstannyl compounds in high yield with retention of stereochemistry of the allylic double bond. In the presence of a Lewis acid (BF3 etherate) these tin compounds couple regio- and stereoselectively with 2-methyl-l,4-naphthoquinone. The reaction to form vitamin K (2) is typical (equation I). ... 

SYNS l-ETHOXY-3,7-DIMETHYL-2,6-OCTADIENE ETHYL GERANYL ETHER 2,6-OCTADIENE, 1-ETHOXY-3.7-DIMETHYL-... 

The authors have found that the same tricyclic ether is obtained with much better selectivity from geranyl phenyl ether (eq 12). Surprisingly, the reaction proceeded smoothly even in the presence of 20 mol % of this LBA to give the desired compound with 77% ee and 98% ds. This reaction is surmised to take place via a [1,3]-rearrangement and subsequent cyclization, although this has not yet been confirmed. 

Other examples are summarized in Table 5. Without exception the use of this LBA resulted in the highest enantioselectivity and diastereoselectivity. The best result of 87 % ee was observed for the cyclization of p-bromophenyl geranyl ether. 

Table 5. Enantioselective cyclization of geranyl aryl ethers with (R)-LBA R...

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