Ketones aldehyde conversion

The Conversion of Organometallic Compounds to Ketones, Aldehydes, Carboxylic Esters, or Amides... 

Both the selenoxide and sulfoxide " reactions have been used in a method for the conversion of ketones, aldehydes, and carboxylic esters to their a, P-unsaturated derivatives (illustrated for the selenoxide). 

The hydrosilylation of carbonyl compounds by EtjSiH catalysed by the copper NHC complexes 65 and 66-67 constitutes a convenient method for the direct synthesis of silyl-protected alcohols (silyl ethers). The catalysts can be generated in situ from the corresponding imidazolium salts, base and CuCl or [Cu(MeCN) ]X", respectively. The catalytic reactions usually occur at room tanperature in THE with very good conversions and exhibit good functional group tolerance. Complex 66, which is more active than 65, allows the reactions to be run under lower silane loadings and is preferred for the hydrosilylation of hindered ketones. The wide scope of application of the copper catalyst [dialkyl-, arylalkyl-ketones, aldehydes (even enoUsable) and esters] is evident from some examples compiled in Table 2.3 [51-53],... 

When the enthalpies of reaction between branched ketones and the corresponding 1,1-disubstituted alkenes are calculated using the multiple enthalpies of formation available for the latter, the following ranges are obtained Me/i-Pr, 196.6 to 200.5 Et/i-Pr, 201.2 to 206.6 and Me/t-Bu, 200.5 to 205.1 kJmol-1. Perhaps it is reasonable to conclude that the reaction enthalpies for the branched compounds either will be approximately constant, as for the unbranched ketone/alkene conversions, or will be more endothermic with branching, as in the branched aldehyde/alkene conversions. In either case, the least endothermic reaction enthalpy for the Me/i-Pr conversion above seems inconsistent and therefore the enthalpies of formation for 2,3-dimethyl-l-butene from References 16 or 26, which are essentially identical, should be selected. These enthalpies were also selected in a previous section. However, there is too much inconstancy, as well as too much uncertainty, in the replacement reactions of carbonyls and olefins to be more definitive in our conclusions. 

Upon conversion from alcohol to ketone/aldehyde the active site contains a reduced NADH molecule, which, in conjunction with the hydrophobic nature of the active-site cavity, is believed to raise the pKa of Tyrl51 to above 10. Evidence is provided by studies demonstrating pH-independent binding of acetaldehyde to the E-NADH complex so that the pKa value for the amino acid responsible for interaction with acetaldehyde is higher than 10. 

The data published before 1996 on the conversion of ketones (aldehydes) into 1,5-disubstituted tetrazoles 5 through geminal diazides 520 have been collected and systematized <2004SOS( 13)861 > (Scheme 74 Table 31). 

An important recent advance in the area is the demonstration that allyl chlorides readily form allylcopper species upon exposure to highly activated copper ( Rieke copper ). The resultant allylcoppers have been shown to react with a fairly wide range of nucleophiles (ketones, aldehydes, acid chlorides, enones, epoxides [after conversion to the cuprate], imines, and allyl bromides)56. Regiochemical considerations in such substitutions depend upon the cases studied, and are fairly complex. The allylcoppers formed have, in all cases, the least substituted C—Cu bond allyl transfer from these reagents is selective from the imposition of the allyl (enone electrophiles excepted)(equations 41 and 42). The allyl chloride... 

Among the many reactions of these species is the conversion to chiral species such as 18-D-XIX. This compound can be obtained in enantiomerically pure form and can be converted to the CpRe(NO)PPh3 ion.69 This ion is a chiral Lewis base that binds a variety of prochiral molecules (olefins, ketones, aldehydes, amines). With these adducts one may conduct numerous reactions where enantiomeric excesses >98% are obtained. As an example, a prochiral methyl ketone will bind selectively, as in 18-D-XX and is then subject to attack by R X to produce only one enantiomer of the RR MeCO product. 

With the catalysts derived from (S,S)-l,2-bis(diphenylphosphinomethyl)cyclobutane and [RhH(CO)(PPh3)3] or rhodium carbonyls, the a,3-unsaturated aldehydes, neral and geranial, are hydrogenated to (E)- and (S)-citronellal in 79% and 60% ee, respectively. Cyclic a,3-unsaturated ketones such as isophorone and 2-methyl-2-cyclohexenone have been hydrogenated using ruthenium hydrides coordinated with chiral diphosphines in up to 62% ee to give chiral ketones, though conversions are not satisfactory. ... 

LiAlH4 is a versatile reducing agent for many organic compounds, such as ketones, aldehydes, nitriles, and nitro compounds. This ion also has many applications in inorganic synthesis. Examples of the inorganic conversions effected by LiAlH4 include... 

Pyridine bases such as 3-picoline and MEP are predominantly manufactured by the Chichibabin reaction, where a mixture of aldehydes or ketones is reacted with ammonia. Thus, formaldehyde, acetaldehyde and ammonia react in the gas phase to produce a mixture of pyridine and 3-picoline. By choosing the appropriate aldehyde or ketone, catalyst and phase (liquid or gas phase), the composition of the mixture can be varied at will, depending on the desired end-product. In the gas phase, silica alumina catalysts are often used, while in the liquid phase acid catalysts based on phosphoric or acetic acid are employed. In the 1990s, Reilly patented MET and BEA-based zeolite catalyst compositions for ammonia-aldehyde conversions to pyridine, picolines and alkyl pyridines. 

For separation of the olefins, reliance was placed largely on efficient fractional distillation under pressure, using techniques now familiar to the petroleum industry the unusual feature was the low temperature required for concentration of ethylene. The main olefin reactions developed were hydration with sulfuric acid to give the alcohol, which was then dehydrogenated to the corresponding aldehyde or ketone, and conversion to the olefin oxide by reaction with hypochlorous acid. The ready commercial availability of the olefin oxides led to a continuous stream of new products, such as glycols, glycol ethers, and alkanolamines. 

Conversion of silyl enol ethers of ketones to a,p-unsaturated ketones or coupling to 1,4-diketones by means of Ag20 or Pd(ll) for a one pot conversion of ketones, aldehydes or alcohols to a,0-unsaturated ketones (aldehydes) with iodoxybenzoic add see Nicolaou. 

Milder than LiAlH4. Generally used for aldehydes, ketones and conversion of acid chloride or esters to aldehydes. 

This reaction was initially reported by Grundmann in 1936. It is the conversion of acyl chloride into aldehyde with the exact same carbon skeleton via the following consecutive steps a) treatment of acyl chloride with diazomethane to form a ketone, (b) conversion of such a ketone into ketol acetate with acetic acid, (c) reduction of ketol acetate with aluminum isopropylate, and d) hydrolysis and oxidation with lead tetraacetate. This method is especially useful in the preparation of aliphatic aldehydes with methylene-interrupted double bond(s). Although polymers might form in the preparation of highly unsaturated aldehydes during the reduction with aluminum isopropylate, the reduction from lithium aluminum hydride can eliminate such drawbacks. ... 

Other functionality can be incorporated into the ylid prior to reaction with an aldehyde or ketone. Aldehyde 1.195, for example was converted 1.196 by reaction with a fluorine-bearing phosphonate ylid. 5 The ester group was reduced to an aldehyde moiety (see 1.197) with diisobutylaluminum hydride. This allowed final conversion to 5-(N-Boc amino)-4-fluoro-6-phenylhex-3E-enoic acid (1.198), in four steps (3% overall yield the first and second steps gave a combined yield of 14% and step five proceeded in 28% yield). 

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