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Dialdehydes from

In order to gain more insight into this proposed mechanism, Montgomery and co-workers tried to isolate the intermediate metallacycle. This effort has also led to the development of a new [2 + 2 + 2]-reaction.226 It has been found that the presence of bipyridine (bpy) or tetramethylethylenediamine (TMEDA) makes the isolation of the desired metallacycles possible, and these metallacycles are characterized by X-ray analysis (Scheme 56).227 Besides important mechanistic implications for enyne isomerizations or intramolecular [4 + 2]-cycloadditions,228 the TMEDA-stabilized seven-membered nickel enolates 224 have been further trapped in aldol reactions, opening an access to complex polycyclic compounds and notably triquinanes. Thus, up to three rings can be generated in the intramolecular version of the reaction, for example, spirocycle 223 was obtained in 49% yield as a single diastereomer from dialdehyde 222 (Scheme 56).229... [Pg.328]

Chinese researchers reported a synthetic route to photochrome 16 (Scheme 7), in which the aldehyde functions are then transformed into cyclic acetals and thioacetals, methylol and dicyanoethylene groups (07T5437, 08T2576). Scheme 7 also gives (at the bottom) symmetrical photochrome 17 (where R are ferrocenyl substituents), which does not exhibit fluorescence in the initial state, but shows fluorescence in the cyclic form and which is also synthesized starting from dialdehyde 16 (08AFM302). [Pg.6]

Encouraged by our previous results, we studied the allylation of bifunctional sulfones derived from dialdehydes such as terephthalaldehyde and isophtha-laldehyde (Scheme 3). When the classical conditions for the preparation of sulfones... [Pg.78]

Intramolecular Aldol Reaction Starting from Dialdehydes... [Pg.174]

The Wittig [75] and the McMurry reaction [76] are standard methods to form C=C double bonds. For example, the bridged biphenylene 98 was prepared in diluted solution by Wittig reaction [75a]. Vogel synthesized the bridged (14]annu-lene 100 with its phenanthrene perimeter from dialdehyde 99 by McMurry reaction [76 c]. 7t-Spherand 101 could be prepared likewise. Because of its a-orbitals... [Pg.23]

Aldehydes form O-stannyl ketyls with the BujSn radical. A /3-alkoxyacrylate unit five bonds away from the ketyl is well positioned to be involved in a radical transfer process therefore, cyclization ensues. Fused oxacycles of well-defined stereochemistry are assembled by this reaction. Heterocyclic 1,2-amino alcohols are similarly procured from dialdehyde monooxime ethers. ... [Pg.370]

Condensation with aldehyde mixtures of two components A and B gives six different porphyrins two parent porphyrins and four hybrid porphyrins (cis- and trans- A B, AB, and A3B). Direct access to trans-A B porphyrins is best achieved with an aldehyde reacting on a-free dipyrromethanes. Capped porphyrins can be obtained from dialdehydes and pyrroles. Even a huge w-steroidal dialdehyde yields the corresponding porphyrin in 7% yield (Scheme 6.3.2)... [Pg.284]

Polyesters also form by the Tischenko reaction from dialdehydes. The intramolecular hydride transfer reaction is typically catalyzed by bases ... [Pg.289]

Similarly, the bicyclo[2.2.2]octene double bond in 28 was readily opened in a domino ROM/double RCM process, leading to tricyclic bisenone 29 with catalyst 2 under ethylene atmosphere in good overall yield from dialdehyde 27 (Scheme 2.11) [7]. Compound 29 was successfully utihzed as the key intermediate in a total synthesis of the bioactive diterpenoid (-l-)-cyanthiwigin U. [Pg.35]

Trisdimethylamino phosphine Oxido compounds from dialdehydes... [Pg.271]

Isocyclics from dialdehydes and aliphatic nitro compounds... [Pg.619]

Miscellaneous Reactions of LR. Under particular conditions, certain carbonyl compounds and other substrates react with LR to form thiophosphonates or heterocycles, which fact throws some hght on the mechanism of thionation reactions with LR. Carbinols undergo nucleophilic substitution with LR to form the corresponding thiols. The redox properties of LR can be utilized to prepare dithiolactones from dialdehydes (eq 22), a-0X0 thioamides from nitro ketones (eq 23), or sulfides from sulfoxides. ... [Pg.55]

Ligands H2LI768 and H2LI769 may be obtained from dialdehydes shown in scheme 8-8 ( = 1,2) and 2-methyl-l,2-propanediamine (Eq. 8.47). To synthesise these compounds a somewhat modified method was chosen, employing Ba(CF3S03)2 as the matrix source, and the reaction was carried out under high dilution conditions [110, 114]. [Pg.505]

Cyclic SchifT bases from dialdehydes and di- or polyamines ... [Pg.438]

Cyclic SchifT bases derived from dialdehydes and diamines... [Pg.861]

Figure 7 Assessment of reduction in human neutrophil elastase activity from several oxidized cotton gauze samples. Untreated cotton gauze was employed as a control Treatment 7 Treatment 2 Treatment 3. Elastase activities are compared in terms of initial velocities for solutions taken from dialdehyde cotton gauze samples. Data are mean + SE of triplicate determinations. Figure 7 Assessment of reduction in human neutrophil elastase activity from several oxidized cotton gauze samples. Untreated cotton gauze was employed as a control Treatment 7 Treatment 2 Treatment 3. Elastase activities are compared in terms of initial velocities for solutions taken from dialdehyde cotton gauze samples. Data are mean + SE of triplicate determinations.
From dialdehydes and aliphatic amines [Fe(CH3N=CHCH=NCH3)3]l2 ) 324.5 110 c. Gouy 69S25... [Pg.185]

Silyl enol esters result from silyl-substituted ally alcohols (using RLi derivatives), from a-haloketones, enolizable aldehydes or ketones (using Nal/Mes-SiCl), from dialdehydes and (MesSi)2NH, and from anions of thioesters e.g.y Bu C=C(OSiMe3)SPh]. /3-Seleno- and /S-thiosilyl enol ethers are formed from the enone on reaction with RSH-MeaSiCl-CgHsN. On storing for long periods, silyl enol ethers condense to symmetric ketones, so should be redistilled before use. ... [Pg.119]

Bn2NH2][OCOCF3]) achieved the second aldol reaction to afford the hemiacetal 150 in 99% ee and 14% yield from dialdehyde 148. The hemiacetal 150 was then transformed to a diastereomeric mixture of methoxy acetals 151 using Amberlyst-15 and MgSO. Conjugate addition of the mixed vinyl cuprate 152 to methoxy acetal 151, followed by trapping with trimethylsilyl chloride, furnished the silyl enol ether 153. [Pg.157]


See other pages where Dialdehydes from is mentioned: [Pg.67]    [Pg.272]    [Pg.913]    [Pg.988]    [Pg.498]    [Pg.563]    [Pg.480]    [Pg.565]    [Pg.565]    [Pg.364]    [Pg.81]    [Pg.71]    [Pg.438]    [Pg.135]    [Pg.494]    [Pg.229]    [Pg.112]    [Pg.204]    [Pg.488]    [Pg.264]    [Pg.184]    [Pg.266]   
See also in sourсe #XX -- [ Pg.1564 , Pg.1681 ]




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Carbohydrates the “dialdehydes” from

Dialdehyde

Dialdehydes

Diols cyclic, from dialdehydes

Diols from dialdehydes

Epoxides from dialdehydes

Guthrie, R. D.,The “Dialdehydes” from

Intramolecular Aldol Reaction Starting from Dialdehydes

Maleic dialdehyde , from

Oxidation the “dialdehydes” from

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