1- Propene, 3-bromo 2-methyl

ACETATE], 32 1 Propene, 2-methyl-, 35 2-Propen-l-ol, 2-bromo 3-phenyl-, acetate, 35... 

Propanone, 1-phenyl- [Benzyl methyl ketone), 55,94 Propene, 0 >l-bromo- 55, 108 Propene, (Z)-l-bromo- 55, 108 Propene, (F) 1 chloro-, 55, 104 Propene, (Z) 1 chloro, 55, 107 2-PROPENENITRILE, 2-(l,l-dimcthylethyl)... 

The results of the olefin oxidation catalyzed by 19, 57, and 59-62 are summarized in Tables VI-VIII. Table VI shows that linear terminal olefins are selectively oxidized to 2-ketones, whereas cyclic olefins (cyclohexene and norbomene) are selectively oxidized to epoxides. Cyclopentene shows exceptional behavior, it is oxidized exclusively to cyclopentanone without any production of epoxypentane. This exception would be brought about by the more restrained and planar pen-tene ring, compared with other larger cyclic nonplanar olefins in Table VI, but the exact reason is not yet known. Linear inner olefin, 2-octene, is oxidized to both 2- and 3-octanones. 2-Methyl-2-butene is oxidized to 3-methyl-2-butanone, while ethyl vinyl ether is oxidized to acetaldehyde and ethyl alcohol. These products were identified by NMR, but could not be quantitatively determined because of the existence of overlapping small peaks in the GC chart. The last reaction corresponds to oxidative hydrolysis of ethyl vinyl ether. Those olefins having bulky (a-methylstyrene, j8-methylstyrene, and allylbenzene) or electon-withdrawing substituents (1-bromo-l-propene, 1-chloro-l-pro-pene, fumalonitrile, acrylonitrile, and methylacrylate) are not oxidized. 

If photolyzed with light of the intensity I, HBr adds to propadiene (la) in the gas phase with a rate given by v=kexp[HBr]I<). This transformation affords within the detection limit (GC) 2-bromo-l-propene (5a) as sole reaction product (Table 11.1). The conversion of methyl-substituted allenes, such as lc and If, under these conditions follows the same kinetic expression [37]. Results from competition experiments indicate that the reactivity of an allene towards HBr increases progressively with the number of methyl substituents from propadiene (la) (= 1.00) to 2,4-dimethylpenta-2,3-diene (If) (1.65). In all instances, Br addition occurs exclusively at Cp to furnish substituted allyl radicals, which were trapped in the rate determining step by HBr. 

It is possible to obtain anti-Markovnikov products when HBr is added to alkenes in the presence of free radical initiators, e.g. hydrogen peroxide (HOOH) or alkyl peroxide (ROOR). The free radical initiators change the mechanism of addition from an electrophilic addition to a free radical addition. This change of mechanism gives rise to the anh-Markovnikov regiochemistry. For example, 2-methyl propene reacts with HBr in the presence of peroxide (ROOR) to form 1-bromo-2-methyl propane, which is an anh-Markovnikov product. Radical additions do not proceed with HCl or HI. 

It is interesting and of preparative value that although 1-bromo-2-methyl-l-propene and similar halides add to 1-hexene at both double-bond carbons, only one of the two 7r-allylic intermediates reacts with the amine. The result is that a mixture of six isomeric dienes is formed, but only one allylic amine is produced. Therefore the reaction is useful since the dienes and the amine are separated easily (2). 

The effect of chain length on the catalytic performance was investigated using a series of co-bromo-2-methylalkenes. In all cases the predominant enantiomer produced had the -configuration except for 3-bromo-2-methylpropene oxide, which was predominantly in the S-form due to the priority switch [274], The short propene and butene derivatives were converted quantitatively whereas the longer pentene, hexene and heptene substrates failed to convert completely. Many other functional groups such as carboxylic ester, methoxy, acetoxy and carbonic ester are accepted by the system. The epoxidation fails, however, for 4-hydroxy-2-methyl-l-butene as substrate [270]. 

To a 2 L, 3-neck Morton flask fitted with a thermometer, a mechanical stirrer, and an addition funnel was added the methyl 3-hydroxy-2-methylene-3-phenylpropionate (305.9 g, 1.585 mol) followed by addition of 48% HBr (505 ml, 4.46 mol) in one portion. The flask was immersed in an ice-water bath, at which time concentrated sulfuric acid (460 ml, 8.62 mol) was added dropwise over 90 min and the internal temperature of the reaction mixture was maintained at 23°-27°C throughout the addition process. After removal of the ice-water bath, the mixture was allowed to stir at room temperature overnight. The solution was then transferred to a separatory funnel and the organic layer was allowed to separate from the acid layer. The acids were drained and the organic layer was diluted with 2 L of a 1 1 ethyl acetate/hexane solution, washed with saturated aqueous sodium bicarbonate solution (1 L), dried over sodium sulfate, and concentrated to yield 400.0 g (99%) of the desired (Z)-l-bromo-2-carbomethoxy-3-phenyl-2-propene as a light yellow oil, which was used without any additional purification, boiling point 180°C (12 mm). 

Add 2-(4-methyl-3-cyclohexenyl)-3-bromo-1-propene (8.06 g, 37.5 mmol) over a 4 h period via the dropping funnel. 

The photolysis of (Me3Si)3SiPh in the presence of functional substituted olefins is of considerable interest (55). Irradiation of 20 with a low-pressure mercury lamp in the presence of vinyl chloride or l-bromo-2-methyl-propene affords the respective 1-alkenyl-1-halo-1-phenyltrimethyldisilanes as the sole volatile product. The fact that the reaction of trimethylsilylphenylsilylene with butyl bromide does not give any volatile products suggests that compound 23 and 24 must come from a 1,2-halogen shift of... 

In Kiyooka s approach to acetate aldols by use of a stoichiometric amount of 3f, the enantiomeric excess obtained in the reaction with silyl ketene acetals derived from a-unsubstituted acetates was much lower (ca 10-20 %) than that obtained in the reaction with l-ethoxy-2-methyl-l-(trimethylsiloxy)-l-propene (> 98 % ee). Introduction of an removable substituent, e.g., a methylthio or bromo substituent, after aldol reaction at the a-position of chiral esters, resolved this problem [43e], Asymmetric synthesis of dithiolane aldols was achieved in good yield by using the silyl ketene acetal derived from l,3-dithiolane-2-carboxylate in the 3f-promoted aldol reaction, and desulfurization of the dithiolane aldols resulted in production of the acetate aldols in high enantiomeric purity (Eq. 56). 

Inverse addition of phenylmagnesium bromide to methyl 4-bromocrotonate affords 13 % of the cyclopropane product (equation 85). Alkyl magnesium bromides do not show any MIRC product at alP . On the other hand 3-bromo-l-(phenylsulphonyl)-l-propene... 

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