2- Butanone aliphatic aldehydes

V-Acylation of oxaziridine (54) is of more importance, yielding 2-acyloxaziridines which were unaccessible otherwise until recently. Oxaziridines (54) derived from cyclohexanone, butanone or benzaldehyde are acylated readily by acetic anhydride, acid chlorides or isocyanates. Oxaziridines from aliphatic aldehydes, too unstable to be isolated, may be trapped in situ by benzoylation (67CB2593). 

The two established Hnls, those from L. usitatissimum and P. amygdalus, have found biocatalytic applications for the production of (i )-cyanohydrins. The former of these Hnls is the least widely applied, the natural substrates being acetone cyanohydrin or (i )-2-butanone cyanohydrin (Table 1) [28]. Although an improved procedure for the purification of this enzyme has been reported [27] it is still only available in limited quantities (from 100 g of seedlings approximately 350 U of enzyme are obtained). It was found that this enzyme transforms a range of aliphatic aldehyde and ketone substrates [27], the latter of which included five-membered cyclic (e.g. 2-methylcyclopentanone) and chlorinated ketone substrates. In contrast, attempts to transform substituted cyclohexanones and 3-methylcyclopentanone failed and it was even found that benzaldehyde deactivated the enzyme. 

A wide range of donor ketones, including acetone, butanone, 2-pentanone, cyclopentanone, cyclohexanone, hydroxyacetone, and fluoroacetone with an equally wide range of acceptor aromatic and aliphatic aldehydes were shown to serve as substrates for the antibody-catalyzed aldol addition reactions (Chart 2, Table 8B2.6). It is interesting to note that the aldol addition reactions of functionalized ketones such as hydroxyacetone occurs regioselectively at the site of functionaliztion to give a-substitutcd-fi-hydroxy ketones. The nature of the electrophilic and nucleophilic substrates utilized in this process as well as the reaction conditions complement those that are used in transition-metal and enzymatic catalysis. 

Treatment of 1-morpholino-l-cyclohexene with ketene gives l-morpholino-2-acetyl-l-cyclohexene251 as the main product, whereas enamines prepared from aliphatic aldehydes yield cyclo-butanones.252,253 Ketene may be generated directly in the reaction medium from acid chlorides and triethylamine. 

Linum usitatissimum Flax seedlings overexpression Acetone cyanohydrin (R)-2-Butanone cyanohydrin Aliphatic aldehydes and ketones (R)... 

Butanone reacts with formaldehyde and other aliphatic aldehydes under mildly basic conditions to give monosubstitution products at C-3 (e.g. equations SO and Sl). Hie behavior of aromatic aldehydes with this ketone is complex condensation at both C-1 and C-3 has been reported. 

Dubois and Fellmann have studied the kinetic regioselectivity in the base-promoted reactions of 2-bu-tanone and 2-pentanone with a series of aliphatic aldehydes (equation 52) results are summarized in Table 2. The data indicate that steric effects play a subtle role in the determination of aldol regiochem-istry in unsymmetrical ketones. Although reaction at C-3 is favored for 2-butanone with all of the aldehydes, pivalaldehyde gives more reaction at C-1 than the other aldehydes studied. Selectivity for reaction at C-3 in 2-pentanone is significantly less with all aldehydes, especially pivalaldehyde. 

Aliphatic aldehydes and ketones. The mass spectra of formaldehyde, 3-penta-none, 3-methyl-2-butanone, 4-methyl-2-pentanone, 3-methyl-2-pentanone, and 2,3-butanedione have been given as Unknowns 1.9,4.9,4.10,4.16,4.17, and 5.2 those of 2- and 6-dodecanone are Figures 3.10 and 3.11 those of 2-ethylhexanal, 6-methyl-2-heptanone, and 6-methyl-5-heptene-2-one are shown in Figures 9.8 to 9.10. 

Eq. 59), and even surprisingly high for aliphatic ketones such as 2-butanone, a substrate that offers very little steric discrimination (Eq. 60). Reagent 74 is less effective than 70 in allylations of aldehydes (e.g., 90% ee vs. >98% ee for 70 in the allylation of benzaldehyde). The superior reactivity and selectivity of 74 with ketones is ascribed in part to the lesser steric bulk of the phenyl substituent compared to the trimethylsilyl unit of reagent 70. The smaller phenyl substituent of 74 would provide a better fit for ketones in the chiral pocket of the reagent. 

BUTANONE (78-93-3) Forms explosive mixture with air (flash point 30°F/—1°C also reported at 16°F/—9°C). Violent reaction with strong oxidizers, aldehydes, nitric acid, perchloric acid, potassium fcrt-butoxide, oleum. Incompatible with inorganic acids, aliphatic amines, ammonia, caustics, isocyanates, pyridines, chlorosulfonic acid. Able to form unstable peroxides in storage, or on contact with 2-propanol or hydrogen peroxide. Attacks some plastics. Flow or agitation of substance may generate electrostatic charges due to low conductivity. 

P,7-Unsaturated ethers of cyanohydrins, on formation of lithio derivatives, undergo a 2,3-sigmatropic rearrangement to form. y-unsaturated ketones (equation 21), whereas benzylic ethers of aliphatic cyanohydrins gave o-methylaryl ketones. The method has been used to prepare 3-methyi-l-(3-methyl-2-furyl)-l-butanones, a naturally occurring Cio terpene, a-allenic ketones and enolic monoethers of 7-keto aldehydes via 2,3-sigmatropic rearrangement of tiieir respective carbanions. ... 

A rational combination of two privileged chiral backbones, such as those of cinchonidine and proline, was efficiently applied by Xiao et al. to promote the aldolisation of aliphatic ketones, such as acetone and 2-butanone, with aromatic aldehydes, providing the corresponding aldol adducts in good yields and high enantioselectivities of up to 97% ee (Scheme 2.23). The presence of the... 

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