Methyl vinylketone

The question of regioselectivity arises when nonsymmetrically substituted alkenes, such as acrylates, acrylonitrile, (methyl)vinylketone, and cinnamic acid... 

Methyl vinylketone Hydroxylamine Thionyl chloride Potassium carbonate... 

Enantioselectivities of 21-70% ee were observed in the reaction of ethyl- and methyl-vinylketone with aromatic aldehydes 22 using the chiral hydroxy-pyrrolizidine-catalyst 24 which was prepared in four steps starting from BOC-I-prolinol (Scheme 5) [32]. The enan-tioselectivity was explained by the predominant formation of intermediate 26-A, which is less sterically hindered than the isomeric intermediate 26-B. The employment of a reaction temperature of -40 °C, the use of NaBF4 as a co-catalyst, and the presence of a hydroxy group in the base (which allows the formation of intramolecular hydrogen bonds) resulted in good conversions and rates. 

The photoinduced cycloaddition of the carbene complex 506 with methyl vinylketone provided the 1-pyrroline 507 (Equation 139) <20020M4076, 20000M3082>. 

Dicarbonyl compound 52 being strongly acidic undergoes a Michael addition with methyl vinylketone (MVK) and the intermediate products can be cyclized to s/wVo-cyclohexenone 68 (Scheme 64, ref. 65). 

Scheme 23 also outlines a potential problem with the syjnthesis. The initial attack can occur at either end of the double bond of the 7r-complex, 28, to give the two isomers 29 and 30 in a ratio of 4 1. These two isomers are expected from Wacker chemistry since propene produces both acetone and propanal in about the same ratio from the two modes of addition. However, as shall be discussed below, this is not a serious problem with most a-olefins. The same catalyst oxidizes methyl vinylketone only to 4-chloro-3-hydroxy-2-butanone (29 R = C(=0)CH3). The optical purity was still only about 12%. 

A thermal rearrangement of 2-methyleneoxetanes to a,-unsaturated methylketones has been reported, and on heating, the oxetenes formed undergo electrocyclic ring opening to give methyl vinylketones (Scheme 43). ... 

Also, a cobalt-catalyzed diastereoselective reductive [3+2] cycloaddition of allenes to enones is observed. Thus phenylallene reacts with methyl vinylketone 340 in the presence of Col2(dppe)/Zn and ZnU, to give the cyclopentane derivative 341 in 88 % yield... 

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