2,7-Dimethyl-1,6-dioxaspiro undecane

Polybia occidentalis W-VG Alarm (2S,6R,8S)-2,8-Dimethyl-1,7-dioxaspiro-[5.5] undecane 142 [188]... 

Enantiomers of 2,7-dimethyl-l,6-dioxaspiro[4.5]decane 28 Enantiomers of 2-Ethyl-7-methyl-l,6-dioxaspiro[4.5]decane 29 Enantiomers of 2,8-dimethyl-l,7-dioxaspiro[5.5]undecane 30 5 - Methylh eptan - 2 -ol (Z)-Non-3-en-l-ol 3,7-Dimethyloctan- l-ol Benzaldehyde 2-Phenylethanol Phenylacetonitrile Isobutyl benzoate Isopentyl benzoate Hexadecanoic acid 17-Hydroxyan drost-4-en-3-one (2)-Octadec-9-enoic acid... 

Mercuriocyclization has also been utilized in order to obtain spiroketals from hemiketals. Thus, treatment of l,10-undecadien-6-one (11) with mercury(II) acetate in water/tetrahydrofuran affords, with total regioselectivity, 2,8-bis[(chloromercurio)mcthyl]-l,7-dioxaspiro[5.5]undccanc as a diastereomeric mixture. The diastereomeric ratio was not reported but depends on the reaction time, owing to the reversibility of oxymercuration-cyclization steps. Reductive removal of mercury by sodium borohydride under phase-transfer conditions gives a good yield of 2,8-dimethyl-l,7-dioxaspiro[5.5]undecane (12) as a diastereomeric mixture101,102. 

Male palaearctic bees (Andrena wilkella) in Sweden produce 2,8-dimethyl-l,7-dioxaspiro[5.5]undecane (88, Figure 4.34) as their pheromone. Its (25, 6R,83 )-isomer is pheromonally active, while the opposite enantiomer (2R,6S,8R)-88 is inactive.63 There are six stereoisomers of 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane (88), three as shown in Figure 4.34 and their opposite enantiomers. Due to the oxygen-anomeric effect, (2S,6R,8S)-88 and its opposite enantiomer are the stable isomers. 

The volatile component of the mandibular secretion of Andrena haemorrhoa F. contains 2,7-dimethyl-l,6-dioxaspiro[4.6]undecane. All four thermodynamically stable stereoisomers of the Spiro acetal pheromone have been prepared using the two enantiomers of ethyl lactate (which supplies the 2-methyl substituent via butyrolactone 51) and the two enantiomers of 3-hydroxybutanoate (which supplies the 7-methyl via iodide 52). Scheme 8 shows the synthesis of the (2S, 5S, 7/ )-isomer 55. The overall yield in the sequence is 9%, and the purity of the final product is 97% [18]. 

The synthesis of (2 5, 6R, 8 S)-2,8-dimethyl-l,7-dioxaspiro[5,5]undecane (868), one of the spiroacetal components of the pheromone isolated from the olive fruit fly, hinges on a dialkylation of tolylmethyl isocyanide with bromide 866. The bromide is obtained from 845b by sequential reduction of the olefin and ester followed by conversion of the resulting alcohol to bromide. Acidic hydrolysis of dialkylated product 867 provides the pheromone 868 directly... 

Dimethylpropylene monoketal 4,4-Dimethyl-2,6-dioxaspiro[6.6 undecan-9-one CiiHigOj M 198.261... 

Thus, starting from ethyl (5)-p-hydroxybut5rrate, pheromones of diverse structural types, such as (5)-sulcatol [26], femilactone II [27], (25,6i )-2-methyl-l,7-dioxaspiro[5.6]-dodecane [28], (25,6/ ,S5)-2,8-dimethyl-l,7-dioxaspiro[5.5]undecane [29], (2R,5S)-2-methyl-5-hexanolide [31], and (2S,SjR)-8-methyl-2-decanol propanoate [32], have been synthesized. Methyl (5)-P-hydroxybutyrate has also been used for the synthesis of (25,35,75)-3,7-dimethylpentadecan-2-ol [33]. In these syntheses, the configurations at the... 

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