Methyl isopropenyl ketone

Chemical Designations - Synonyms Isopropenyl methyl ketone 2-Methyl-l-butene-3-one Chemical Formula CH3COC(CH3)=CHi. 

Japanese workers (50,51) were the first to observe optical activity in the addition of thiols to electron-poor olefins (eq. [9]) The e.e. was not determined, but these observations led us to attempt using a cinchona alkaloid as the catalyst in the addition of thiophenol to cyclohexenone. The reaction lends itself admirably to a scope, limitations, and mechanism study, and the results have been published in detail (19). An important mechanistic difference between the addition of the dodecanethiol to isopropenyl methyl ketone and the addition of thiophenol to a cyclohexenone (eq. [1]) lies in the sequence of chirality-producing steps. In the former case, chirality is produced when the proton adds to the a-caibon atom of the ketone—after thiol addition has taken place. In the latter... 

Table 3. A mmetnc addition of dodecanethiol to isopropenyl methyl ketone catalyzed by poly (-r-benzyl S-glutamate) (PBLG ) (16)...

Differently from poly(7-benzyl S-glutamate) (PBLG), poly( -benzyl S-aspartate) (PBLA) is known to amme a left-handed a-helical conformation which is less stable than the a-helical conformation of PBLG (20). In this respect, it is of interest to examine the asymmetric addition of dodecanethiol to isopropenyl methyl ketone [Eq. (9)] catalyzed by the terminal amino group of PBLA. By using PBLA, prepared by the polymerization of the corresponding NCA in a mixture of 1,2-dichloroethane and tetrahydrofuran with butylamine as initiator, Fukushima and Inoue (21) observed the occurrence of asymmetric nthesis as own in Table 4. 

Thus, in the a mmetric nthesis observed in the addition of dodecanethiol to isopropenyl methyl ketone catalyzed by the terminal amino grcmp of poly(a-amino acid), the secondary conformation of the polymer catalyst plays an important role. The mechanistic pathway of this addition reaction is as follows (24,25), in which... 

Pinacolone (rert-butyl methyl ketone) is transformed into pivalic acid (trimethylacetic acid) in 71-74% yield [737], Mesityl oxide is converted into 3,3-dimethylacrylic acid in 49-53% yield [703], Isopropenyl methyl ketone gives methacrylic acid in 41% yield [697], and pregnenolone acetate furnishes 3-acetoxyetienic acid in 91-95% yield [117J] (equations 421-424). 

Two new preparations of 1,8-cineole (553) [the biogenesis of which from geraniol (25) in Rosmarinus officinalis has been elucidated ] have been recorded. A Diels-Alder adduct 625 (R = Me) of methyl vinyl ketone and isopropenyl methyl ketone was converted to the diazoketone (R = CH = N2) with diethyl oxalate/base, then toluenesulfonyl azide, and treatment of the latter with [Rh(OAc)2]2 in methylene chloride at room temperature for five minutes converted it in very high yield to the tricyclic compound 626. Lithium dimethylcuprate then yielded the ketone 627, conversion of which to 1,8-cineole (553) was known.The other 1,8-cineole synthesis was a by-product of an observation which enabled the two stereoisomers of limonene 1,2-epoxide to be separated. The cjs-epoxide 549 was brominated to stereoisomers of a dibromocineole 628, under conditions when the rran.s-epoxide did not react, and could be distilled pure afterward. The dibromo compound 628 yielded 1,8-cineole (553) with tributyltin hydride. 

D.30) 3-Buten-2-one, 3-methyl-, 3-methylbut-3-en-2-one, isopropenyl methyl ketone [814-78-8]... 

ISOPROPENYL METHYL KETONE (814-78-8) Forms explosive mixture with air (flash point 68°F/20°C). Violent reaction with aldehydes, nitric acid, perchloric acid, strong oxidizers. Contact with hydrogen peroxide can form unstable peroxides heat and/or inappropriate level of inhibitor may cause polymerization. 

Oxidation of unsaturated ketones such as mesityl oxide, methyl vinyl ketone, isopropenyl methyl ketone, chalcone, and 2-cyclohexenone to the corresponding epoxides can also be effected by tert-butyl hydroperoxide in the presence of Triton B 50 and similar conditions have been used for epoxidation of [Pg.280]

B Reaction temp. 35 °C, dodecanethiol 25 mmole, isopropenyl methyl ketone 37 mmole, n molar ratio of NCA to initiator in the preparation of PBLG. 

Reaction temp., 35 °C dodecanethiol, 25 mmole isopropenyl methyl ketone,... 

Metbyl-3-buten-2-one Isopropenyl methyl ketone CsHgO 814-78-8 84.117 lig -64 98 0.86275" 1.42205" vs EtOH... 

The copolymerization of Cinchona alkaloids with acrylonitrile affords copolymers which behave as very useful catalysts in asymmetric synthesis, arguably the most effective reported to date. For example, in the addition of dodecanethiol to isopropenyl methyl ketone a 57% enantiomer excess was reported this is the highest value ever recorded for an asymmetric synthesis that is catalysed by an organic polymer. 

An improved synthetic reaction involving isopropenyl methyl ketone and isoprene in benzene in the presence of stannic chloride for 105 min at 0°C gave a 70% yield of (450) containing less than 4% of isomeric material. ... 

Isopropenyl methyl ketone Single T FTIR NMR - Hong et al. (1995a)... 

Figure 15a shows an ESR spectrum observed in the reaction of poly(NMAAm) radicals with isopropenyl methyl ketone (IPMK). This spectrum is similar to that of the poly(MMA) radical and has therefore been assigned to the propagating polymer radical (X) of IPMK. 

The principal drawback to using alkaloids as catalysts in asymmetric synthesis is the separation of the product from the catalyst. This has been overcome by radical copolymerization of cinchona alkaloids with vinyl monomers in a way that retains the stereoselectivity of the alkaloid. The reaction of dodecanethiol with isopropenyl methyl ketone in toluene in the presence of quinidine acrylonitrile copolymer (21) gives the (+) enantiomer, in excess, 57 % ee, which is claimed to be the highest value ever achieved in the asymmetric reactions catalysed by synthetic organic copolymers. Previous studies with this type of polymeric catalyst had shown poor asymmetric efficiencies. ... 

Isopropenyl Methyl Ketone Methyl Isopropeuyl Kerosene Kerosene... 

Poly(5-benzyl-L- glutamate addition dodecylmercaptane + isopropenyl methyl ketone opt-active product large [a] d observed [110]... 

---