1.2- Dimethyl-5-isopropenyl

The aggregation pheromone of the boU weevil, Jinthonomusgrandis is a mixture of the alcohols D-i7j -2-isopropenyl-l-methylcyclobutaneethanol [30820-22-5] (168) and OT-3,3-dimethyl-A, p-cyclohexaneethanol [26532-23-0] (169) and of the cis- and trans-isomers of the aldehyde of the latter (170). The pheromone is marketed as grandlure [11104-05-5] for monitoring and removal trapping of boU weevil populations. 

Isoxazole, 4-iodo-3,5-dimethyl-reactions, 6, 59 Isoxazole, 3-iodo-5-phenyl-synthesis, 6, 86 Isoxazole, 3-isopropenyl-oxidation, 6, 27, 54 polymerization, 6, 54 Isoxazole, 3-isopropenyl-5-methyI-polymers, 1, 282... 

The dimethyl acetal (94) is readily prepared from the 22-aldehyde (93) by direct reaction with methanol in the presence of hydrogen chloride. Ena-mines (95) are formed without a catalyst even with the poorly reactive piperidine and morpholine.Enol acetates (96) are prepared by refluxing with acetic anhydride-sodium acetate or by exchange with isopropenyl acetate in pyridine.Reaction with acetic anhydride catalyzed by boron trifluoride-etherate or perchloric acid gives the aldehyde diacetate. 

The chlorination of 3-isopropenyl-5-methylisoxazole and of dimethyl-(5-methylisoxazol-3-yl)carbinoP and, recently, the bromina-tion of 5- and 3-phenylisoxazoles and unsubstituted isoxazole have also been studied. Reaction is effected by heating in the presence of powdered iron and gives 4-bromoisoxazoles (63 64, Hal Br R,R = H, Ph). 

Olefins analogous to 158 and 159 were also isolated from the CuS04-catalyzed decomposition of ethyl diazoacetate in the presence of 2-isopropenyl-2-methyl-1,3-dithiane (total yield 56%, E Z — 4 1) a butadiene was absent from the reaction mixture 161). With dimethyl diazomalonate instead of ethyl diazoacetate, only the Z-olefin resulting from a [2,3]-sigmatropic rearrangement of the corresponding sulfur ylide was obtained in 36 % yield 161). When the same procedure was applied to... 

Intramolecular oxonium ylide formation is assumed to initialize the copper-catalyzed transformation of a, (3-epoxy diazomethyl ketones 341 to olefins 342 in the presence of an alcohol 333 . The reaction may be described as an intramolecular oxygen transfer from the epoxide ring to the carbenoid carbon atom, yielding a p,y-unsaturated a-ketoaldehyde which is then acetalized. A detailed reaction mechanism has been proposed. In some cases, the oxonium-ylide pathway gives rise to additional products when the reaction is catalyzed by copper powder. If, on the other hand, diazoketones of type 341 are heated in the presence of olefins (e.g. styrene, cyclohexene, cyclopen-tene, but not isopropenyl acetate or 2,3-dimethyl-2-butene) and palladium(II) acetate, intermolecular cyclopropanation rather than oxonium ylide derived chemistry takes place 334 ). 

Dimethyl (1, R,2 R,5,R)-2-(2 -isopropenyl-5 -methylcyclohex-1 -yl)-propane-1,3-dioate Propanedioic acid, [5-methyl-2-(1-methylethenyl)cyclohexyl]-, dimethyl ester, [1R-(1a,2p,5o)]- (12) (106431-81-6)... 

DIASTEREOSELECTIVE FORMATION OF TRANS-1,2-DISUBSTITUTED CYCLOHEXANES FROM ALKYLIDENEMALONATES BY AN INTRAMOLECULAR ENE REACTION DIMETHYL (1 R,2 R,5 R)-2-(2 -ISOPROPENYL-5 -METHYLCYCLOHEX-1 -YL)-PROPANE-1,3-DIOATE... 

Selenophene was also obtained as the main component in the reaction between vinylacetylene and the selenium dianion, generated from elemental selenium (Se8), in dimethyl sulfoxide-potassium-water at 100-120°C.5° Bis-y,y-dimethylallenyl selenide (18) is converted by spontaneous cyclo-aromatization to 3-isopropenyl-4-isopropylselenophene (19).51 Two mechanisms are shown in Scheme 3. 

Diketones. Some years ago Heiba and Dessau reported that Mn(OAc), promotes oxidative addition of isopropenyl acetate to ketones to give 1,4-diketones in 20-35% yield (6, 356). Use of CAN as the oxidant results in higher yields (65-80%) and a regioselective reaction at the more substituted a-position of the ketone.1 Use of vinyl acetate results in the dimethyl acetal of 4-oxo aldehydes. 

When D-gulono-1,4-lactone was treated with isopropenyl methyl ether and a catalytic amount of p-toluenes ulfonic acid in N,N-dimethyl-formamide, 5,6-0-isopropylidene-D-gulono-1,4-lactone (51) was formed in 95% yield.176 Previously, this compound was available in only low yield as a mixture of products. In addition, 51 was converted into 2,3-di-O -acetyl-5,6-0 -isopropylidene-D-gulono-1,4-lactone by treatment with acetic anhydride. 

The major product is l,4-dimethyl-4-vinylcyclohexene together with smaller amounts of 1,6-dimethylcyclo-octa-l,5-diene, isoprene and 4-isopropenyl-1 -methylcyclohexene. 

Irreversible Transesterification. A new preparation of chiral glycerol acetonide (2,2-dimethyl-l,3-dioxolane-4-methanol) involving an enantioselective hydrolysis of 2-0-benzylycerol diacetate to the (R)-monoacetate catalyzed by a lipoprotein lipase (47) has recently been developed. In an effort to prepare the (S)-enantiomer, we have used the aforementioned irreversible transesterification reaction using isopropenyl acetate as an acylating reagent, which upon reaction gives acetone as a... 

A GENERAL [3+2] ANNULATION CIS-4-EXO-ISOPROPENYL-1,9-DIMETHYL-8-(TRIMETHYLSILYL)BICYCL0[4.3.0]N0N-8-EN-2-0NE... 

Treatment with dimethyl sulfoxide in the presence of phenyl dichlorophosphate or phosphoryl chloride converts ( + )-a-pinene (39) to (6/ ,4.S)-4-isopropenyl-l-methyl-6-chlorocyclohexene (51) in virtually quantitative yield, presumably also via the cyclobutylmethyl to pent-l-enyl cation rearrangement.164 Similarly, / -pinene (45) is converted to 4-isopropenyl-l-chloromethylcyclohexene (52), also in quantitative yield.164... 

Curculionidae. The boll weevil, Anthonomus grandis, that great despoiler of cotton in the southern U. S., synthesizes a quaternary blend of sex pheromones that have been collectively labeled grandlure. Four compounds that interact synergistically have been identified as (+)-2-(cis-isopropenyl-1-methylcyclobutyl) ethanol (XI), (Z)-2-(3,3-dimethyl cyclohexylidene)ethanol (XII), (Z.)-2-(3,3-dimethylecyclohexylidene)acetaldehyde (XIII), and (Ej-2-(3,3-dimethylcycloh.exylidene)acetaldehyde (XIV) (54). 

Saturated branched Isopropyl, Isobutyl, sec-Butyl, tert-Butyl. Also use pina-colyl instead of 1,2,2-trimethylpropyl. However, pinacolyl alcohol should preferably be named 3,3-dimethyl-2-butanol. Unsaturated Vinyl, Allyl, Isopropenyl. 

The formation of a carbon-carbon bond at the -position of carbamates has been achieved when a-methoxy-/ -bromocarbamates were allowed to react with carbon nucleophiles such as dimethyl malonate or isopropenyl acetate (equation 12)11. 

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