Tertiary amine base

Allylation under basic conditions. Allylation can be carried out under basic conditions with allylic acetates and phosphates, and under neutral conditions with carbonates and vinyloxiranes. The allylations under neutral conditions are treated separately in Section 2.2.2.1 from those under basic conditions. However, in some cases, allylations of the same substrates are carried out under both basic and neutral conditions to give similar results. These reactions are treated together in this section for convenience. Allylic acetates are widely used for Pd-catalyzed allylation in the presence of bases tertiary amines or NaH are commonly used[6,7,4l]. As a base, basic alumina or ICF on alumina is conveniently used, because it is easy to remove by filtration after the reaction[42]. Allyl phosphates are more reactive than acetates. The allylation with 40 proceeds stepwise. At first allylic phosphate reacts with malonate and then allylic acetate reacts with amine to give 41(43]. 

In practice it is found that reactions 1 and 2 are of greatest importance and ester and ether linkages occur in roughly equal amounts. The reaction is modified in commercial practice by the use of organic bases, tertiary amines, to catalyse the reaction. 

Here, as with the 4-HO-DMT (psilocin) and the 4-HO-DET entries, some care must be made with the use of the term "acetate" or "phosphate." As these materials are both bases (tertiary amines) and acids (hydroxy indoles), they are in effect internal salts. For stability, they are usually converted into salts (at the amine end) or esters (at the phenolic end), or both. In this context, the term "acetate" can mean either modification, a salt or an ester involving acetic acid. And, of course, a phosphate can be either a salt or an ester. I will try to append the additional term "salt" or "ester" whenever this ambiguity is possible. In all of these studies, the acetate is the ester, and some of these are free bases, some are the hydrochloride salts and some are the fumarate salts. 

Weak base Tertiary amine (aliphatic matrix) jl— CH,NR2... 

Weak base Tertiary amine Polystyrene Dowex AG 3... 

Two main routes have been described for the preparation of hydantoins cyclization of urea-derivatized amino acids and of carbamate-bound amino acid carboxamides (Figure 15.10) [95, 96]. In the first route, a bound amino acid is treated with an isocyanate to obtain the urea that is subsequently cyclized and released by acid (HC1) or base (tertiary amines) catalysis upon warming (60-100 °C) [95, 97]. The second route employs a carbamate linkage to attach the amino acid through the amino... 

In 2004, Vignola and List [111] demonstrated the ability of proline-derived catalysts to overcome drawbacks associated with the stoichiometric alkylation of preformed aldehyde enolates when they described an elegant amino acid catalyzed intramolecular a-alkylation reaction of haloaldehydes. The reaction furnished substituted cyclopentanes, cyclopropanes, and pyrrolidines in good yields and good enantio-selectivities (Scheme 8.23), when commercially available (5)-a-methyl proline (LV) as catalyst was used. The presence of a stoichiometric amount of additional base (tertiary amine) was required, not only to trap the hydrogen halide produced in the reaction but also because it has also significant effect on the stereoselectivity of the C—C bond-formation process by stabilizing the ant/ -TS of the /ra 5-enamine intermediate. Nevertheless, an intermolecular version of the reaction remains still elusive, mainly because of the deactivation of the amine catalyst by A -alkylation with the alkyl halide [112]. 

Reactions of isocyanates with alcohols are catalyzed by a variety of compounds, including bases (tertiary amines, alkoxides, and carboxylates), metal salts and chelates, organometallic compounds, acids, and urethanes. The most widely used catalysts in coatings are organotin (IV) compounds, most commonly dibutyltin dilaurate (DBTDL) (dibutylbis[(l-oxododecyl)oxy]stannate) [77-58-7] and tertiary amines, commonly diazabicyclo[2.2.2]octane (DABCO). Combinations of DABCO and DBTDL often act synergistically. 

In contrast with the above findings in water, condensations in chloroform exhibit a considerable specificity of the base used as a catalyst, as shown by two model reactions ethyl nitroacetate with norbornene and benzoylnitromethane with styrene [65]. A screening of several organic bases (tertiary amines and heteroaromatic A-bases with one or two basic sites) applied to these reactions indicates that the results are not related to the base strength. In fact, the most effective bases are those with the highest H-bonding basicity [74], particularly those having two basic sites, like DABCO, NMI, etc. [75-77]. 

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