2,2,5-Trimethyl-5-hexenal

Hence measurements have been made on unsubstituted allyl alkali-metal compounds, and also on neopentylallyl (I, 5,5-dimethylhexen-2-) and neopentylmethallyl (II, 2,5,5-trimethyl-hexen-2-) alkali-metal compounds which are models of the polymerizing chain end in the anionic polymerization of butadiene and isoprene respectively. 

Two approaches for the synthesis of allyl(alkyl)- and allyl(aryl)tin halides are thermolysis of halo(alkyl)tin ethers derived from tertiary homoallylic alcohols, and transmetalation of other allylstannanes. For example, dibutyl(-2-propenyl)tin chloride has been prepared by healing dibutyl(di-2-propenyl)stannane with dibutyltin dichloride42, and by thermolysis of mixtures of 2,3-dimethyl-5-hexen-3-ol or 2-methyl-4-penten-2-ol and tetrabutyl-l,3-dichlorodistannox-ane39. Alternatively dibutyltin dichloride and (dibutyl)(dimethoxy)tin were mixed to provide (dibutyl)(methoxy)tin chloride which was heated with 2,2,3-trimethyl-5-hexen-3-ol40. 

Intramolecular secondary aminostyrenes 95-97 were also studied100. iV-2,2-Trimethyl-3-phenyl-3-buten-l-amine 95 was irradiated to obtain the elimination product 98 (equation 29). Irradiation of Af-methyl-4-phenyM-penten-l-amine 96 results in a single product 99 in 80% yield by GC analysis (equation 30). Similarily, irradiation of iV-methyl-5-phenyl-5-hexen-l -amine 97 results in the formation of a single product 100 in 70% yield (equation 31). The photochemistry of the (aminopropyl) indene 101 is also similar (equation 32). 

Biological. The pure culture Aspergillus niger biodegraded isophorone to 3,5,5-trimethyl-2-cyclo-hexene-l,4-dione, 3,5,5-trimethylcyclohexane-l,4-dione, (5)-4-hydroxy-3,5,5-trimethyl-2-cyclohex-l-one, and 3-hydroxymethyl-5,5-dimethyl-2-cyclohexen-l-one (Mikami et al, 1981). 

The fact that about five times as much of 2,3,4,4-tetramethyl-l-pentene (XXXVIII) was obtained as its 2-isomer (XXXIX) indicates that the loss of a proton from either of the two methyl groups takes place about five times as easily as do the loss of the proton on the tertiary carbon atom that is part of the neopentyl system. Similarly, the relative amounts of 3,5,5-trimethyl-2-hexene and its 3-isomer (XL and XLI) indicates that the loss of a proton from the ethyl group occurs about five times as readily as from the neopentyl group no loss of a proton from the methyl group appears to have occurred. By analogy with the formation of the two isomeric diisobutylenes from the ear-bonium ion VI it would be expected that the carbonium ion XLII which leads to the formation of 2,4,4-trimethyl-2-hexene (XLIII) would yield the 1-isomer in about four to five times the amount of the 2-isomer. The failure to find any of the 1-isomer was little less than startling (Whitmore and Mixon, 47). 

Effect noted experimentally, but data insufficient to quantitate. r Includes measurements on propylene through 1-hexene, 2-ethyl-l-butene, and 2,4,4-trimethyl-l-pentene. 

Die in situ hergestellten Trifluormethansulfonsaure-Salze von 5-Amino-1-penten, 6-Amino-l-hexen und einigen ihrer Derivate werden in Gegenwart von Bis-[benzonitril]-palladium-dichlorid in Tetrahydrofuran cyclisiert, z. B. zu 2-Methyl-pyrrolidin (65%), l-Isopropyl-2-methyl-pyrrolidin (78%), 2,4,4-Trimethyl-pvr-rolidin (73%) und 2-Melhyl-piperidin (76%). ... 

Growe and co-workers independently reported a procedure for the cyclization/hydrosilylation of enones and enals similar to that reported by Buchwald." As an example, reaction of a 1 1 mixture of 3,3-dimethyl-5-hexenal and triethoxysilane catalyzed by Gp2Ti(PMe3)2 (20 mol%) in pentane at room temperature for 3 h gave m-l,l,3-trimethyl-4-triethoxysilyloxycyclopentane in 88% yield as a single diastereomer (Equation (38)). 

C11H22O2, Mr 186.30, Z>/>i,6kPa 82°C, Uq 1.441, is a colorless to pale yellow liquid with a fresh fruity citrus grapefruit-peel-like odor. It has not been found in nature. It is prepared by reaction of 2,2,5-trimethyl-4-hexenal (from isobutyraldehyde and prenyl chloride) with methanol in the presence of calcium chloride [21]. 

The lactone intermediate is prepared in another industrial process by cyclization of homofarnesic acid in the presence of SnCU as a catalyst [184]. Pure diastereomers are obtained by acid cyclization of trans- and cw-4-methyl-6-(2,6,6-trimethyl-cyclohex-l(2)enyl)-3-hexen-l-ol, prepared from 2-methyl-4-(2,6,6-trimethylcyclo-hex-l(2)-enyl)-2-butenal [185]. 

The edible portion of broccoli Brassica oleracea var. italica) is the inflorescence, and it is normally eaten cooked, with the main meal. Over 40 volatile compounds have been identified from raw or cooked broccoli. The most influential aroma compounds found in broccoli are sulfides, isothiocyanates, aliphatic aldehydes, alcohols and aromatic compounds [35, 166-169]. Broccoli is mainly characterised by sulfurous aroma compounds, which are formed from gluco-sinolates and amino acid precursors (Sects. 7.2.2, 7.2.3) [170-173]. The strong off-odours produced by broccoli have mainly been associated with volatile sulfur compounds, such as methanethiol, hydrogen sulfide, dimethyl disulfide and trimethyl disulfide [169,171, 174, 175]. Other volatile compounds that also have been reported as important to broccoli aroma and odour are dimethyl sulfide, hexanal, (Z)-3-hexen-l-ol, nonanal, ethanol, methyl thiocyanate, butyl isothiocyanate, 2-methylbutyl isothiocyanate and 3-isopropyl-2-methoxypyrazine... 

Problem 6.1 Write structural formulas for (a) 3-bromo-2-pentene, (b) 2,4-dimethyl-3-hexene, (c) 2,4,4-trimethyl-2-pentene, (d) 3-ethylcyclohexene. 

Fig. 2.4. Chromatographic profiles of volatiles emitted by four plant species at different time periods after an attack by Spodoptem littoralis larvae. The labeled peaks are 1, (Z)-3-hexenal 2, ( )-2-hexenal 3, (Z)-3-hexenol 4, (Z)-3-hexenyl acetate 5, linalool 6, ( )-4,8-dimethyl-1,3,7-nonatriene 7, indole 8, ( )-/ -caryophyllene 9, ( ,)-o -bergamotene 10, ( >/3-farnesene 11, ( , )-of-farnesene 12, nerolidol 13, ( , )-4,8,12-trimethyl-1,3,7,11-tridecatetraene 14, of-pinene 15, /3-pinene 16, -myrcene 17, D-limonene 18, ( )-/3-ocimene 19, -sesquiphellandrene 20, germacrene D. Two internal standards, -octane and nonyl acetate, are labeled with IS1 and IS2, respectively.

Epoxide formation is nearly suppressed when massively subeti-tuted olefine, such as 2,2,4-trimethyl-3-hexene among others, ate subjected to the chromic oxide-acetic anhydride reagent,42 Cyclo-hexene yields primarily 2-cyclohexenone and cyclohexane- 1,2-dione777 although some cyclohexane oxide appears to bo formed also (Eq, 111). 

The hydroformylation of several olefins in the presence of Co2(CO)8 under high carbon monoxide pressure is reported. (S)-5-Methylheptanal (75%) and (S)-3-ethylhexanal (4.8%) were products from (- -)(S)-4-methyl-2-hexene with optical yields of 94 and 72%, respectively. The main products from ( -)(8)-2,2,5-trimethyl-3-heptene were (S)-3-ethyl-6,6-di-methylheptanal (56.6%) and (R)-4,7,7-trimethyloctanal (41.2%) obtained with optical yields of 74 and 62%, respectively. (R)(S)-3-Ethyl-6,6-dimethylheptanal (3.5% ) and (R)(S)-4,7,7-trimethyloctanal (93.5%) were formed from (R)(S)-3,6,6-trimethyl-l-heptene. (+/S)-l-Phenyl-3-methyl-1-pentene, under oxo conditions, was almost completely hydrogenated to (- -)(S)-l-phenyl-3-methylpentane with 100% optical yield. 3-(Methyl-d3)-l-butene-4-d3 gave 4-(methyl-d3)pentarwl-5-d3 (92%), 2-methyl-3-(methyl-d3)-butanal-4-d3 (3.7%), 3-(methyl-d3)pentanal-2-d2,3-d1 (4.3%) with practically 100% retention of deuterium. The reaction mechanism is discussed on the basis of these results. 

Photochemical isomerization of a,/3-unsaturated ketones to 0,7-un-saturated ketones via the enol appears to be a general reaction. An equilibrium mixture of 4,5,5-trimethyl-3-hexen-2-one (Formula 166) and its d,7-unsaturated isomer (Formula 167) is converted by irradiation in a quartz vessel to the pure /3,7-unsaturated ketone (Formula 167) (66). 

The adsorption of organic compounds on nascent surfaces can be considered as an acid-base reaction. According to the hard-soft acid and bases HSAB principle (Ho, 1977), polar compounds such as carboxylic acid and amine (with lone pair electrons on oxygen or nitrogen) are classified as "hard bases". A hard base reacts more easily with a hard acid than with a soft acid. Metals are classified as soft acids which react much more easily with soft bases than hard bases. The results in Table 5.1 can be explained with this concept. The soft bases (benzene, 1-hexene, diethyl disulfide) react easily with the nascent surface as a soft acid. On the other hand, the hard bases such as propionic acid, stearic acid, propyl amine and trimethyl phosphate exhibit a very low activity (Fischer et al., 1997a and 1997b Mori and Imazumi, 1988). 

The results for the cyclization of the l,l,5-trimethyl-5-hexen-l-yl radical, formed from the reaction of l,l,5-trimethyl-5-hexenyl-l-bromide (3) with Bu3SnH/AIBN, are shown in eq. 3.2. These results indicate that the ratio of 5-exo-trig marmer/6-endo-trig manner depends on both the temperature and concentration of Bu3SnH. Thus, as the concentration of Bu3SnH at 40 °C is decreased (which means the decrease of the concentration of the hydrogen donor), both a decrease of the direct reduction product,... 

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