Reactions with carbonyl compounds ketones

Reaction With Carbonyl Compounds. Primary and secondary nitroparaffins undergo aldol-type reactions with a variety of aldehydes and ketones to give nitro alcohols (11). Those derived from the lower nitroparaffins and formaldehyde are available commercially (see Nitro alcohols). Nitro alcohols can be reduced to the corresponding amino alcohols (see Alkanolamines). 

A-Substituted pyrroles, furans and dialkylthiophenes undergo photosensitized [2 + 2] cycloaddition reactions with carbonyl compounds to give oxetanes. This is illustrated by the addition of furan and benzophenone to give the oxetane (138). The photochemical reaction of pyrroles with aliphatic aldehydes and ketones results in the regiospecific formation of 3-(l-hydroxyalkyl)pyrroles (e.g. 139). The intermediate oxetane undergoes rearrangement under the reaction conditions (79JOC2949). 

Other aromatic heterocycles undergo Patemo-Btichi reaction with carbonyl compounds, although these reactions have seldom been applied to organic synthesis. For example, thiophene reacts cleanly with benzaldehyde to afford a single exo product in 63% yield87. Pyrroles also react with aldehydes and ketones however, as a result of the lability of the presumed initial cycloadducts, the only products isolated, even with the rigorous exclusion of acid, are the 3-hydroxyalkylpyrroles 200 (equation 7)89. 

Aldehydes and ketones are formed in reactions with carbonyl compounds, e.g. oximes, diacetyl and CO + tetraalkyltin172 (see also Zollinger7 11). 

According to the Cd 18-90 AOCS ° official method, the ANV is 100 times the optical density measured in a 1 cm cell, at 350 nm, of a solution containing 1.00 g of oil in 100 ml of the test solution. The measured absorbance is due to Schiff bases (167) formed when p-anisidine (166) undergoes condensation reaction with carbonyl compounds, according to equation 55. The carbonyl compounds are secondary oxidation products of lipids, such as a, S-unsaturated aldehydes and ketones derived from the hydroperoxides (see Scheme 1 in Section n.A.2.c), and their presence points to advanced oxidation of the oil. 

Silyl-l,3-dienes undergo anodic methoxylation in methanol to give 1,4-addition products with an allylsilane structure as intermediates. Therefore, they are further oxidized to give l,l,4-trimethoxy-2-butene derivatives as the final products. The products are easily hydrolyzed to provide the corresponding y-methoxy-a, /t-unsaUirated aldehydes. Since 1-trimethylsilyl-l,3-dienes are readily prepared by the reaction of the anion of l,3-bis(trimethylsilyl)propene with aldehydes or ketones, l,3-bis(trhnethylsilyl)propene offers a, /i-formylvinyl anion equivalent for the reaction with carbonyl compounds (equation 15)16. 

Phenylytterbium iodide, C6H5YbI. This reagent can be prepared by reaction of C6H5I with Yb powder in THF. In reactions with carbonyl compounds, it behaves in the same way as Grignard reagents, except that it reacts more readily with esters than with ketones.12... 

P. J. Murphy, J. Brennan, The Wittig Olefination Reaction with Carbonyl Compounds Other than Aldehydes and Ketones, Chetn. Soc. Rev. 1988, 17, 1-30. 

The above transformation has two different goals 21,22) 1) To increase chemo-, regio-, diastereo- and enantioselectivity in the reaction with carbonyl compounds (Sections C-E), and 2) to make certain reaction types amenable which do proceed readily with classical reagents, e.g., methylation of tertiary alkyl halides, alcohols and ethers, and direct geminal dialkylation of ketones (Section F). It turns out that organotitanium compounds are usually complementary to Li, Mg, Zn, Fe, Ni, Cu and Pd reagents. So far, experience in the above two areas points to the following positive aspects ... 

Aldol reaction. Quantitative yields of 1,2-adducts of alkyllithiums to ketones can be obtained at -65° in the presence of Cel,. Cerium enolates, formed by reaction of CeCl, with lithium enolates, also show enhanced reactivity in reactions with carbonyl compounds, particularly ketones. Yields of aldols are increased, but the stereoselectivity remains moderate. ... 

The well-known reaction of phosphorus ylides is their reaction with carbonyl compounds (aldehydes and ketones) to give alkenes. This alkenation methodology is universally known as the Wittig reaction . ... 

Murphy, P J, Brennan, J, The Wittig olefination reaction with carbonyl compounds other than aldehydes and ketones, Chem. Soc. Rev., 17, 1-30, 1988. 

The triethylaluminum or triethylborane ate complexes (12) of the (isopropylthio)allyl carbanion react with carbonyl compounds at the a-position (equation 10). In the reactions with carbonyl compounds, very high regioselectivity (for example, butanal 95 5, 3-methylbutanal 99 1, cyclohexanone 92 8 and acetophenone 95 5) was achieved by using the aluminum ate complex. On the other hand, the a-regio-selectivity with ketones decreases if the boron ate complex is used (cyclohexanone 72 28, acetophenone 45 55). It is noteworthy that the stereoselectivity of the a-adduct from an aldehyde is low. Ihesumably the geometry of the double bond in the ate complex (12) is not homogeneous. ... 

Johnson and Tait prepared a trimethylsilylmethylcerium reagent and examined its reaction with carbonyl compounds. The reagent adds to aldehydes and ketones including many readily enolizable ones to afford 2-hydroxysilanes. This modified Peterson reagent gives vastly superior yields in comparison with trimethylsilylmethyllithium. An example is shown in Scheme 9. 

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