Carboxymethylating reagent

Carboxymethyl)tr(methy(ammonlum chloride hydrazlde (Reagent T ). A cooled soKilion of ethyl chioroacetate (984 g, 6.65 mol) was treated with irimethylamine (200 g, 3.39 mol). After 12-24 h a second portion of trimethylamlne (200 g, 3.39 mol) was added. After complete consumption of ethyl chioroacetate, hydrazine (4C0 g) was added. The product was tillered and dryed under vacuum (H2SO4) to afford 1100 g of T (90%). 

The gummy residue is treated with 7.8 grams of Girard s "T" reagent, a commercially available (carboxymethyl) trimethylammonium chloride hydrazide which can be prepared by the method described by Girard in Organic Syntheses, collective volume II, page 85... 

Some part of the cellulose fraction is redirected to make cellulose derivatives, such as cellulose acetate, methyl and ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. These derivatives find multiple applications, for instance, as additives in current products (e.g., paints, lacquers) of chemical industry. Typically, the preparation of cellulose derivatives takes place as a two-phase reaction cellulose is pretreated, for example, with alkali, and a reagent is added to get the substitution. Usually no catalyst is needed [5]. 

To further explore this phenomenon, we prepared a variety of base on alumina reagents. Their activity in the carboxymethylation of benzyl bromide is presented in Table IV. 

The next task was to form the C2-C3 aldol bond stereoselectively. However, asymmetric coupling of acetate derivatives to aldehydes is often accompanied by poor / -induction [89]. Moreover, the C3-C4 bond is particularly sensitive to retro-aldol reaction, especially under basic conditions. In the natural products, this was observed to be the main decomposition reaction. The first total syntheses of epothilones circumvented this problem by constructing this part of the molecule in an indirect manner, e.g., by using reduced forms at Cl or C5. We decided to employ our chromium-Reformatsky methodology, which avoids these problems and allows the direct use of reagents in the correct oxidation state. The non-basic reaction conditions, the intermediacy of a chromium(III) aldolate that is resistant to retro-aldol reaction, and the potential of a direct asymmetric carboxymethyl ( acetate ) transfer favor the use of this method [90]. 

Carboxymethyl)trimethylammonium chloride hydrazide see Girard reagent T. 

Hydrazide, e.g., (carboxymethyl)trimethylammonium chloride hydrazide (Girard T reagent) [4, 56], andp-toluenesulfonhydrazide [36] and hydroxylamine [25]... 

Ketenes are highly reactive electrophiles but not nearly so indiscriminate as carbenes. When the properties of diazoacetyl photoaffinity reagents were evaluated the Wolff rearrangement was found to be a major problem accounting for 30 to 60% of the products arising from O-esters and 100% of the products fromS-esters. For instance, diazoacetyl-chymotrypsin gave rise to O-carboxymethyl serine formed by the attack of water on the ketene (Shafer et al., 1966) (Fig. 3.10). 

Cationization and carboxymethylation of starch in an extruder has been reported.45 17 Cationization of potato starch in a twin-screw extruder had an optimum reaction efficiency of 71%. Further work yielded 80% efficiency and products with 0.03-0.10 DS.44 Additional heat treatment of extruded products (made via reaction with quaternary ammonium reagents) with sodium trimetaphosphate or citric acid has improved reaction efficiencies and/or viscosities.48 Dry cationization in the presence of methanol and isopropanol49 or combined with microwave irradiation has also been done.50... 

Chiral base was applied in the synthesis of the alkaloid (+)-jamtine (Scheme 65). The key step consisted in deprotonation of the cyclohexane fused imide 93 with the mono-lithiated chiral diamine 94, which allowed highly enantioselective carboxymethylation on quenching with Mander s reagent to give compound 95 in up to 98% ee107,108. 

Treatment of 2-[(carboxymethyl)mercapto]benzoic acid 257 with Vilsmeier reagent (DMF/POCI3) gives 3-chloro-benzo[, ]thiophene-2-carboxaldehyde 258 (Scheme 50) <1996JOC6523>. 

Castellino and Hill (1970) reported that the Met is readily accessible to reagents, in agreement with the model. Also in agreement were the reactivities of His residues. Thus, with iodoacetate, carboxymethylation proceeds in the order His-68 > His-32 > His-107. 

---