Isovaleric anhydride

Dolichotheline (111) is a histamine-derived alkaloid produced by the cactus Dolichothele sphaerica Britton and Rose (Cactaceae) native to southern Texas and northern Mexico. The alkaloid was first isolated in 1969 by Rosenberg and Paul (160). Spectroscopic data suggested structure 111, 4(5)-(iV-isovalerylaminoethyl)imidazole or 7V -isovalerylhistamine. The structure was proved by synthesis. Refluxing of histamine with isovaleric anhydride yielded 111, identical to the natural product (160). In addition to the major alkaloid dolichotheline, five minor alkaloids have been isolated (161). These were identified as A-methylphenethylamine, /i-O-methylsyn-ephrine, vV-methyltyramine, synephrine, and / -0-ethylsynephrine by IR, NMR, and comparison to authentic materials / -0-ethylsynephrine was probably an artifact of synephrine, since it was not found in a second extraction attempt when no ethanol was used. 

An imidazole alkaloid has been isolated for the first time from a cactus species.10 Dolichotheline (7 R = COCH2CH2CHMe2) has been obtained from Dolichothele sphaerica and its structure has been established on the basis of spectral and degradative evidence and confirmed by synthesis from histamine (7 R = H) and isovaleric anhydride. This represents only the second report of a chemical investigation in the genus Dolichothele. 

Methyl isovalerate, azeotropic mixtures with butyl alcohols, 4 395t Methyl ketones, acetic anhydride used in synthesis, 1 148 Methyllithium, 14 249 15 147 Methylmagnesium chloride, 16 319 (R)-(—)-Methylmandelic acid chloride, chiral derivatizing reagent, 6 76t Methyl mercaptan production, 15 17 3-Methylmercaptopropionaldehyde (MMP), intermediate in methionine synthesis, 1 268, 269, 276... 

The carbodiimide method has been employed in several syntheses of depsipeptides. However, direct application of DCC for the formation of the ester bond between the amino acid and hydroxy acid components under the usual conditions of amide coupling affords the desired depsipeptides in acceptable yields only in the case of unhindered co-hydroxy units [54] or an active hydroxy group, such as in TV-benzoyl-u-hydroxyglycine benzyl ester. For example, Ravdel et al.[55 have performed the esterification of various benzyloxycarbonyl- and phthalylamino acids with /V-benzoyl-a-hydroxyglycine benzyl ester with DCC in 50-65% yield. On the other hand, Shemyakin et all21 failed to obtain the expected depsipeptide products on condensation of bulky benzyloxycarbonyl- or phthalylvaline with a-hydroxy-isovaleric acid benzyl ester. The main product was acylurea in the first case and phthalylvaline anhydride in the second. Thus, the classical carbodiimide procedure could not be applied in practical depsipeptide preparation. 

Steric effects were evaluated by a study of the DMAP-catalysed acylation of 1 y, 2y and 3y alcohols by acetic, propionic, isobutyric, isovaleric, and pivalic anhydrides in CH2C12 at 20 °C. In all cases the reaction kinetics could be described by rate laws containing a DMAP-catalysed term and an uncatalysed (background) term. Steric effects were evident in both reactions, but were generally greater for the DMAP-catalysed reaction. For example, the uncatalysed reactions between cyclohexanol and acetic and pivalic anhydrides differed about 500-fold, but for the corresponding DMAP-catalysed reactions the factor was 8000-fold. The implications of these findings for the kinetic resolution of alcohols were discussed.32... 

An improvement resulting in a decreased amount of the second acylation product is the introduction of mixed anhydrides with a-branched carboxylic acids like isovaleric and pivalic acid, due to deactivating electronic and steric effects. 

Glutaric anhydride 203-597-8 Dimethyl malonate 203-601-8 Casmate DCA Dimethylheptyl adipate 203-602-3 Ethyl isovalerate 203-603-9 Arcosolv PMA Dowanol PMA Eastman PM Acetate Ektasolve PM Acetate. Redesignated Eastman PM Acetate Methyl Propasol Acetate Methyl Proxitol Acetate Propylene glycol methyl ether acetate 203-604-4... 

Formation of the peptide bond via mixed or unsymmetrical anhydrides gained considerable popularity after their introduction in the early forties. These intermediates were constructed in such a way that the blocked amino acid is practically the sole acylating moiety while the acid which plays the role of activator is eliminated. Acetic acid or benzoic acid are not well suited for this role. A search for better solutions led to branched long-chain fatty acids, such as isovaleric acid (Vaughan and Osato 1951). In these mixed anhydrides (prepared via the acid chlorides) reactivity of the activating part of the anhydride... 

Isdiated from essential o of Calythrix tetra-gona. Pale yeUow mobile oil with uhpleasant odour. B.j 142"/14 mm. 1-0531. tiS 1 5203. Acid to litmus. Aik. NaOBr—> CHBrs -f isovaleric acid + dimeidiylmaleie anhydride... 

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