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Aider

Classical syntheses of steroids consist of the stepwise formation of the four rings with or without angular alkyl groups and the final construction of the C-17 side-chain. The most common reactions have been described in chapter 1, e.g. Diels-AIder (p. 85) and Michael additions (p. [Pg.277]

Diels-AIder Copolymers. The Diels-Alder reaction can also be employed to obtain thermosetting polyimides. If bismaleimide (the bisdienophile) and the bisdiene react nonstoichiometricaHy, with bismaleimide in excess, a prepolymer carrying maleimide terminations is formed as an intermediate, which can then be cross-linked to yield a temperature-resistant network. [Pg.28]

Diels-AIder reactions, I, 618 reactions, 1, 617-620 synthesis, 1, 614-616 2-Germoxetanes heterosubstituted germacyclobutanes and, 1, 596 Gewald synthesis thiophenes, 4, 888-889 ( )-Gingerol synthesis, 1, 453 (+)-(S)-Gingerol synthesis, I, 435 Ginkgolide A... [Pg.640]

Table 11.4 Relative Reactivity of Substituted Butadienes in tbe Diels-Aider Reaction"... Table 11.4 Relative Reactivity of Substituted Butadienes in tbe Diels-Aider Reaction"...
A qualified first-aider, or nurse, should be ealled immediately to deal with any injury - however slight - ineurred at work. [Pg.429]

The Chiral Lewis Acid-catalyzed Diels-AIder Reaction... [Pg.6]

The Asymmetric Diels-AIder Reaction of a,jS-Unsaturated Aldehydes as Dienophiles 1.2.1.1 Aluminum... [Pg.6]

Chiral aluminum catalyst 2, prepared from Et2AlCl and a Vaulted biaryl ligand, is reported to be an effective Lewis acid catalyst of the Diels-AIder reaction between methacrolein and cyclopentadiene, affording the adduct in 97.7% ee [4] (Scheme 1.2). Although the Diels-AIder reaction with other a,/ -unsaturated aldehydes has not been described, that only 0.5 mol% loading is sufficient to promote the reaction is a great advantage of this catalyst. [Pg.6]

In 1989 Yamamoto et al. reported that the chiral (acyloxy)borane (CAB) complex 3 is effective in catalyzing the Diels-AIder reaction of a number of a,/ -unsaturated aldehydes [5]. The catalyst was prepared from monoacylated tartaric acid and bo-... [Pg.6]

The Asymmetric Catalytic Diek-Aider Reaction Catalyzed by Base 47... [Pg.47]

Diels-Alder reactions in which nitroalkenes act as dienophiles are acceleratedin thepresence of 4 M l.iClOi) in nitromethane This acceleration is higher than that observed when l.iClO is used in diethyl ether The diastereoselecdve Diels-Aider reaction using homochiial nitroalkenes shown in Eq 8 31 has been demonstrated... [Pg.246]

Un puits de service est un puits fore ou equipe en vue d aider la production dans un gisement existant. Les puits de cette categorie sont fores pour remplir diverses fonctions specialisees injection de gaz (gaz naturel, propane, butane ou gaz de combustion), injection d eau, injection de vapeur, injection d air, evacuation d eau salee, alimentation en eau pour I injection, observation, injection en vue de la combustion sur place. [Pg.56]

This interpretation has been challenged by Kamo and co-workers53 who independently studied the same systems and arrived at the conclusion that the polymer arises from the radical homopolymerization of the Diels-AIder adduct through its residual double bond, to give structure 16. [Pg.63]

The Mayo mechanism involves a thermal Diels-AIder reaction between two molecules of S to generate the adduct 95 which donates a hydrogen atom to another molecule of S to give the initiating radicals 96 and 97. The driving force for the molecule assisted homolysis is provided by formation of an aromatic ring. The Diels-AIder intermediate 95 has never been isolated. However, related compounds have been synthesized and shown to initiate S polymerization."110... [Pg.108]

The identification of both phenylethyl and 1-phenyl-1,2,3,4-lelrahydronaphthalenyl end groups in polymerizations of styrene retarded by FeCl3/DMP provides the most compelling evidence for the Mayo mechanism.316 The 1-phenyl-1.2,3,4-tetrahydronaphthalenvl end group is also seen amongst other products in the TEMPO mediated polymerization of styrene,317318 However, the mechanism of formation of radicals 96 in this case involves reaction of the nitroxide with the Diels-AIder dimer (Scheme 3.63). The mechanism of nitroxide mediated polymerization is discussed further in Section 9.3.6. [Pg.108]

First asymmetric Dieis-Aider reactions in the vinyihetarene series cycioaddition with vinyiindoies to enantiomericaiiy pure carbazoie derivatives [133]... [Pg.83]

Furans act as dienophiies in faciie Dieis-Aider reactions with masked o-benzoquin-ones [153]... [Pg.89]

Synthesis of decalin synthons of bioactive terpenoids Lewis-acid-cataiyzed Dieis-Aider reactions [109]... [Pg.135]

Enantioseiective Dieis-Aider reactions between cyciopentadiene and a, -acetyienic aidehydes cataiyzed by a chirai super Lewis acid [110]... [Pg.135]

Microwave-assisted Dieis-Aider reactions supported on graphite [39a]... [Pg.196]

Microwave-activated Dieis-Aider cycioaddition reactions of 1,2-difiuoro-1-chiorovinyi-phenyisuifone [102]... [Pg.196]

Dieis-Aider reactions of photoenoi of 2-methylbenzaldehyde with 5-alkylidene-1,3-dioxane-4,6-dione derivatives [48]... [Pg.196]

Detergents containing a 1,3-diene group in the hydrophobic segment. Facile chemical modification by a Dieis-Aider reaction with hydrophiiic dienophiies in aqueous solution [69]... [Pg.197]

See other pages where Aider is mentioned: [Pg.135]    [Pg.341]    [Pg.2]    [Pg.334]    [Pg.29]    [Pg.65]    [Pg.127]    [Pg.766]    [Pg.777]    [Pg.95]    [Pg.432]    [Pg.8]    [Pg.212]    [Pg.325]    [Pg.310]    [Pg.423]    [Pg.6]    [Pg.6]    [Pg.22]    [Pg.34]    [Pg.33]    [Pg.493]    [Pg.334]    [Pg.63]    [Pg.133]   


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