Aldehydes dials

A great variety of carbonyl compounds, aldehydes or ketones, can participate to the reaction aliphatic, 5 aromatic, heteroaromatic, or a,P-unsaturated aldehydes, dial-... 

Aldehydes. When the group —C(=0)H, usually written —CHO, is attached to carbon at one (or both) end(s) of a linear acyclic chain the name is formed by adding the suffix -al (or -dial) to the name of the hydrocarbon containing the same number of carbon atoms. Examples are butanal for CHjCHjCHjCHO and propanedial for, OHCCH CHO. 

Auch Li t hi urn a I ana t reduziert die o- und p-standig mit elektronenliefemden Gruppen (z.B. Amino, Dial-kylamino, Methoxy) substituierten aromatischen Aldehyde und Ketone mcist nur unter cncrgischen Bedingun-gen zu Kohlenwasserstoffen (z. B. in Dibutylather mehrere Tage bei 80-90°). Formyl- und Acyl-phenole werden nicht reduziert1. 

The intermediate 8,8 -diapo-20-acetoxycarotene-8,8 -dial (81) has been used to synthesize the cross-conjugated carotenoid aldehydes , y-caroten-20-al (82), (2/ ,2 J )-2,2 -bis-(3-methylbutyl)-3,4,3, 4 -tetrahydro-t/>, /f-caroten-20-al (83),... 

Symmetrical ketones are also prepared from organic halides and carbon dioxide catalyzed by 2,2 -bipyridine-nickel complexes42. Torii and coworkers found a synthetically useful electrochemical allylation, which involves the electroreductive generation of a dial-lyltin reagent in the presence of a catalytic amount of tin. A wide variety of aldehydes and ketones have been added in high yields under relatively mild conditions by this method (equation 19)43. The process was further improved by the addition of catalytic amounts of... 

For syntheses of vitamin A aldehyde (retinal) and higher terpene aldehydes, appropriate 2-methyl-2-butene-1,4-dials (32) with a protected aldehyde function were used as the C5 building blocks. They are accessible, in turn, via the C5 building block p-formylcrotyl acetate (8 b) in the form of its dimethyl acetal, or via P-formylcrotyl methyl ether (29)34 b) ... 

The reaction of the C20 ylide (45 a) with the unsymmetrical C10 dialdehyde, 2,6-dimethyl-2,4,6-octatriene-1,8-dial (49, R = H), shows a remarkable regioselectivity. Only one of the two aldehyde groups participates in a Wittig olefmation, leading uniformly to p-apo-8 -carotenal (48) 4 ). The Wittig reaction between the C20 ylide (45a) and ethyl-2,6-dimethyl-8-al-octatrienoate (49, R = OQHj) correspondingly yields an ethyl-p-apo-8 -carotenate (48, R = OC2H5)s8). 

The common method of naming aldehydes corresponds very closely to that of the related acids (see Carboxylic acids), in that the term aldehyde is added to the base name of the acid. For example, formaldehyde (qv) comes from formic acid, acetaldehyde (qv) from acetic acid, and butyraldehyde (qv) from butyric acid. If the compound contains more than two aldehyde groups, or is cyclic, the name is formed using carbaldehyde to indicate the functionality. The IUPAC system of aldehyde nomenclature drops the final e from the name of the parent acyclic hydrocarbon and adds al. If two aldehyde functional groups are present, the suffix - dial is used The prefix formyl is used with polyfunctional compounds. Examples of nomenclature types are shown in Table 1. 

Dialkylamino aldehydes condense with Grignard reagents to give dial-kylamino alcohols ... 

Analogous pyrrolyl derivatives are also found as furan metabolites. Furans are oxidized by CYP to reactive furan-epoxides, which rearrange to ene-dial or ene-keto-aldehyde metabolites (Figure 33.20). After... 

Diese Aldehyd-Synthesen basieren auf dem Prinzip der Meyers-Aldehydsynthese aus 1,3-Oxazinen (s.S. 384). Ausgehend von 2,4-Dimethyl-1,3-thiazol386 oder 2-Me-thyl-4,5-dihydro-l,3-thiazol413 werden 3-Hydroxy-, 2-Alkyl- und 2,2-Dial-kyl-alkanale hergestellt ... 

Problem 15.19 For the Cannizzaro reaction, indicate (a) why the reaction cannot be used with aldehydes having anaH, —CHCHO U>) the role of OH and OD (Problem 15.18) (c) the reaction product with ethane-dial, O = CH—CH = O (d) the reaction products of a crossed-Cannizzaro reaction between (i) formaldehyde and benzaldehyde, and (ii) benzaldehyde and / - c h I o ro be n zaidehyde. 

As far as is known, the only industrial application of the water-soluble catalyst for the hydroformylation of 5 -functionalized alkenes has been developed by Kura-ray [17]. In this process, 7-octen-l-al is hydroformylated into nonane-1,9-dial, a precursor of nonene-l,9-diol, by using a rhodium catalyst and the monosulfonated tri-phenylphosphine as water-soluble ligand in a 1 1 sulfolane/water system. At the completion of reaction, the aldehydes are extracted from the reaction mixture with a primary alcohol or a mixture of primary alcohol and saturated aliphatic hydrocarbon (cf. Section 6.9). 

Furan and 2-methylfuran yield 2-butene-1,4-dial and 4-oxo-2-pcntenal, respectively, with cis/trans ratios 95/5 and 97/3. Due to the presence of water the aldehydes enter equilibria towards hydrates and were not isolated in a pure state. Conditions Furan or the (di)methylfuran (10 mmol) with H2O2 (15 mmol as 35 wt % aqueous solution) and 0.1 g of TS-1 in acetonitrile (10 ml) are stirred for 3 h at 20 °C. Analysis was carried out by GC. 

Bei der Hydrierung von Azomethinen niederer Aldehyde mit Platin in Athanol/Essig-saure treten zusatzlich Hydrolyse und Aldol-Kondensationen ein5. Auch mit Raney-Nik-kel werden infolge Nebenreaktionen geringere Ausbeuten an den gewiinschten Dial-kyl-aminen erhalten1,6. 

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