Aldehydes, allylation

This reaction illustrates a stereoselective preparation of (Z)-vinylic cuprates, which are very useful synthetic intermediates. They react with a variety of electrophiles such as carbon dioxide, epoxides, aldehydes, allylic halides, alkyl halides, and acetylenic halides they undergo... 

Several methods and reaction pathways have been reported for the conversion of glycerol in the literature, such as etherification, esterification [1], and oxidation [2], Via ionic dehydration acetol [3] and acrolein can be produced. The radical steps result in aldehydes, allyl alcohol, etc. [4], If the dehydration is followed by a hydrogenation step, propanediols (1,2- or 1,3-) can be obtained [5-6]. 

CAS Number Acraldehyde Acrolein Acryladehyde Acrylaldehyde Acrylic aldehyde Allyl aldehyde Aqualin Aquilin, Magnacide H Propenal 107-02-8... 

Ti-BINOL-catalyzed reactions have been well established. When the Ti is replaced by Zr,92 the resulting complex 140 can also catalyze the addition of allyl-tributyltin to aldehydes (aldehydes allyl-tributyltin 140 = 1 2 0.2 mol ratio) in the presence of 4 A MS. Product l-alken-4-ols are obtained in good yield and high ee. The, Sz-face of the aldehyde is attacked if (S)-BINOL is used, and Re-face attack takes place when (K)-BINOL is used as the chiral ligand. For Zr complex-catalyzed reactions, the reaction proceeds much faster, although the... 

One of the important advantages of the intramolecular alkene silylformylation reaction as an aldol equivalent is that the products are masked 3,5-dihydroxyalkanals, and therefore that no manipulations are required prior to iteration of the process by aldehyde al-lylation to set up the next intramolecular silylformylation. Given that allylsilanes are well-known aldehyde allylation reagents, intramolecular silylformylation employing a diallylhydrosilane would, in principle, allow for the possibility of a tandem silylformyla-tion/allylsilylation reaction. This has been reduced to practice the diaUylsilyl ethers 60 were subjected to the previously developed silylformylation conditions and the unpuri-fied reaction mixtures were subjected to the Tamao oxidation ]36] to provide triols 61... 

The class of 3-silyl-substituted reagents provides, upon addition with aldehydes, allylic silanes that offer many options for further derivatization. Oxidative processes are described in previous sections (see the sections on Preparation of 1,2-Diols and 1,4-Diols). If the appropriate silicon substituents are chosen, formal [3+2] cycloadditions with aldehydes can be promoted under Lewis acid catalysis. For example, the mismatched addition of the Z-3-propyl-3-benzhydryldimethyl allylsilane 183 to an a-benzyloxy aldehyde proceeds with low diastereofacial selectivity in favor of product 184 however, after protection of the secondary alcohol, an efficient [3+2] annulation provides the polysubsubstituted furan 185 in good yield and acceptable stereoselectivity (Scheme 24). ° The latter is brought forward to a tricyclic unit found in the antitumor natural product angelmicin B. 

Hassner et al. (8) reported a novel synthesis of 2,5-dihydroxyoxazoles (32) using an intramolecular azide-alkene cycloaddition. The ratio of reagents (aldehyde/allyl alcohol/hydrazoic acid, 1 3 9) was critical for the preparation of azide 30 (Scheme 9.8). 

ACROLEIN Acraldehyde, Acrylic Aldehyde, Allyl Aldehyde, Ethylene Aidehide, 2-Propenal, Acrylaldehyde Flammable Liquid, III 3 3 2 ... 

Tables 9.3 and 9.4 list selected bond dissociation energies and radical heats of formation. Note particularly that the decrease in energy required to remove hydrogen in the series methane, primary, secondary, tertiary, parallels increasing radical stability, and that aldehydic, allylic, and benzylic hydrogens have bond dissociation energies substantially lower than do alkyl hydrogens.

The synthesis of silicon-containing heterocycles was reported employing Si-C bond-forming <01JOM160> or aldehyde allylation <01TL581> reactions to prepare the metathesis substrates (Scheme 54). 

The combined catalyst of Sc(OTf)3 and distannoxane gives the one-treatment process. Namely, in the reaction of ro-hydroxy alkanal, one-pot aldehyde allylation and acetylation of a primary alcohol are achieved without protection/ deprotection procedures. The unwanted acetylation of a secondary homoallyl alcohol by Sc(OTf)3 is suppressed by hybridization with distannoxane (Equation (46)).151... 

Functional group (FG) = Br, CONR2, CN, C02Et, C02tBu E-Y = aldehyde, allyl bromide... 

Allyltin compounds readily add to aldehydes and ketones. Allylic bromides react with tin to generate the organometallic in situ, which then adds to aldehydes. Allylic chlorides react with aldehydes in the presence of ditin compounds such as MesSn—SnMes and a palladium catalyst. Allyltrialkyltin compounds ... 

Conjugated aldehydes. Allylic alcohols are converted to enals when treated with either palladium cluster complexes or Ru-Al-Mg hydrotalcites" under molecular oxygen. 

The reaction involves stirring aldehyde, allyl bromide, and stannous chloride in water and applying an electrolytic potential of 2.0 V with graphite electrodes. The cathode rednces Sn(ll or IV) salts to tin metal, which react with allyl bromide to generate allyltin(ll) bromide and diallyltin dibromide. These organotin species then allylate the aldehyde and the resulting homoallyl alcohol is extracted with diethyl... 

Pentacoordinate aUylsihcates can be used for allylation of imines as well as carbonyl compounds [423]. Allylation with pentacoordinate crotylsilicates generated from crotyltrifluorosilanes and CsF gives the corresponding homoallylamines efficiently in a regiospecific manner, in the same way as aldehyde allylation (Scheme 10.152). The diastereoselectivity is not high, but it is mostly predictable on the basis of a six-membered cychc transition structure. 

Several routes to 4-alkyl-2,5-dihydrooxazoles, which were not available by previous methods, have been discovered. Thermolysis of allyl a-azidoalkyl ethers (181) gives 2,5-dihydrooxazoles via triazoline intermediates <88JOC27>. The starting materials are obtained from aldehydes, allyl alcohol, and hydrazoic acid (Scheme 89). A hlorination of oxazolidines with r-butyl hypochlorite, followed by dehydrochlorination using potassium superoxide, also provides 4-alkyl-2,5-dihydrooxazoles in 40-93% yield <92TL7751>. 

A related Mukaiyama aldol catalyst system reported by Keck prescribes the use of a complex that is prepared in toluene from (R)- or (S)-BINOL and Ti(0 Pr)4 in the presence of 4 A molecular sieves. In work preceding the aldol addition reaction, Keck had studied this remarkable catalyst system and subsequently developed it into a practical method for enantioselective aldehyde allylation [95a, 95b, 95c, 96]. Because the performance of the Ti(IV) complex as an aldol catalyst was quite distinct from its performance as a catalyst for aldehyde allylation, a careful examination of the reaction conditions was conducted. This meticulous study describing the use of (BINOL)Ti(OiPr)2 as a catalyst for aldol additions is noteworthy since an extensive investigation of reaction parameters, such as temperature, solvent, and catalyst loading and their effect on the enantiomeric excess of the product was documented. For example, when the reaction of benzal-dehyde and tert-butyl thioacetate-derived enol silane was conducted in dichlo-romethane (10 mol % catalyst, -10 °C) the product was isolated in 45% yield and 62% ee by contrast, the use of toluene as solvent under otherwise identical conditions furnished product of higher optical purity (89% ee), albeit in 54% yield. For the reaction in toluene, increasing the amount of catalyst from 10 to 20 mol %... 

Yamamoto has pioneered the use of Ag(I) complexes as Lewis acids for aldehyde allylation [122] and aldol addition [123]. For the aldol addition process, ketone-derived tributyltin enolates have been employed as the nucleophiUc component (Eq. 48). These enolates are readily prepared from the corresponding enolace-tates upon treatment with BujSnOMe. Importantly, although the resulting BujSn-enolates are known to exist as a mixture of C- and 0-bound tautomers 230/231,... 

C.16) 2-Propenal, acry/aldehyde, prop-2-enal, acrolein, acrylic aldehyde, allyl aldehyde [107-02-8]... 

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