Acids tiglic

Tiger s eye Tight-head drums Tiglic acid [80-59-1]... 

Fig. 53. The temperature dependence of 7", in tiglic acid. Methyl tunnel splitting (ueV)...

Cevadine contains neither a methoxyl nor a methylimino group it yields crystalline benzoyl and o-nitrobenzoyl derivatives, m.p. 255° and 236° respectively, and a methiodide, which decomposes at 210-2°, and is converted by silver oxide into eevadinemethylhydroxide.i When warmed with alcoholic soda, cevadine undergoes hydrolysis into eevine and angelic and tiglic acids. When hydrogen chloride is passed into cevadine in alcohol, ethyl tiglate and eevine are formed. ... 

Cevadilline (Sabadilline), Cj HgjOgN, is the amorphous residue, insoluble in ether, obtained in the purification of cevadine. When warmed with alcoholic soda, tiglic acid and cevilline, CggH jO N, are formed (Wright and Luff.i)... 

However, in the case of a-substituted unsaturated esters (4), as for example methacrylic or tiglic acid esters, diazomethane addition results in the formation of stable A pyrazolines (5). The latter products require halogen acids for conversion to the isomeric nonconjugated A -pyrazolines (6). 

These two acids, of the formula C HgO, are geometrical isomerides. They are both unsaturated, and belong to the aci-ylic acid series. Tiglic acid forms crystals melting at 64 5 and boiling at 198 5 , whilst angelic acid melts at 45° to 46° and boils at 185°. They have the following constitutions —... 

These two acids occur chiefly as esters in Roman chamomile oil. Tiglic acid is also found as geranyl tiglate in geranium oil. 

Jessop and co-workers studied asymmetric hydrogenation reactions with the catalyst complex Ru(OAc)2(tolBINAP) dissolved in [BMIM][PFg]. In both reactions under investigation - the hydrogenation of tiglic acid (Scheme 5.2.10) and the hydrogenation of the precursor of the anti-inflammatory dmg ibuprofen (Scheme 5.2.11) - no CO2 was present during the catalytic transformation. However, SCCO2 was used in both cases to extract the reaction products from the reaction mixture when the reaction was complete. 

Scheme 5.2-10 Ru-catalyzed asymmetric hydrogenation of tiglic acid, followed by product...

The first application involving a catalytic reaction in an ionic liquid and a subsequent extraction step with SCCO2 was reported by Jessop et al. in 2001 [9]. These authors described two different asymmetric hydrogenation reactions using [Ru(OAc)2(tolBINAP)] as catalyst dissolved in the ionic liquid [BMIM][PFg]. In the asymmetric hydrogenation of tiglic acid (Scheme 5.4-1), the reaction was carried out in a [BMIM][PF6]/water biphasic mixture with excellent yield and selectivity. When the reaction was complete, the product was isolated by SCCO2 extraction without contamination either by catalyst or by ionic liquid. 

Scheme 5.4-1 Asymmetric, Ru-catalyzed hydrogenation of tiglic acid in [BMIM][PFg] followed by...

Only 5% of the cis isomer, tiglic acid, was produced. In addition, certain carbanions in which the negative charge is stabilized by d-orbital overlap can maintain configuration (p. 233) and SeI reactions involving them proceed with retention of configuration. 

Racemic and enantioselective hydrogenations of tiglic acid each exhibited an apparent activation energy of 17 kJ mol (268 to 308 K). Enantiomeric excess was constant at 20 to 23% over the range 273 to 308 K but lower, 13%, at 268 K. Enantioselective hydrogenation of trifluorotiglic acid exhibited an activation energy of 23 kJ mol" (253 to 323 K) and a temperature-independent enantiomeric excess of 13 2%. 

No geometrical isomerisation of tiglic acid to angelic acid, or vice versa, accompanied hydrogenation... 

Figure I Possible precursor states to the selective enantioface adsorption of tiglic acid...

Acrylic acid (AA) and methacrylic acid (MAA) (purchased from Merck) are freed from inhibitor on a neutral aluminium oxid column and distilled. Acrylamide (AM) from Kebo, Stockholm, is recrystallized once from chloroform solution before use. Other monomers of analytical grade were purchased from Merck and used as received crotonic acid (CA), tiglic acid (TA), 3-methyl crotonic acid (3-MCA), and a-methyl cinnamic acid (oi-MCia) (Table 1). Benzophenone (analytical grade, Kebo) and acetone (spectroscope grade, Merck) were used as supplied. 

A further example is given in reference [88] Selective esterification of retronecine, the dialcoholic component of a pyrolizidine alkaloid, by the imidazolide method was found to be superior to the acid chloride/pyridine method. Acylation of the 9-position of retronecine with tiglic acid, pivalic acid, isobutyric acid, and propionic acid was investigated concerning the steric requirement of the carboxylic acid. 

It has been confirmed that isoleucine but not 3-hydroxy-2-methylbutanoic acid is a precursor for the tiglic acid which is the esterifying acid in some tropane alkaloids [e.g., meteloidine (77) (735)]. In the biosynthesis of meteloidine (77) from 3a-hydroxytropane (1), the hydroxyl groups at C-6 and C-7 are most probably introduced after esterification at C-3 (5) (Scheme 23). In this connection we would point out that scopolamine (89) is a well-known 2,3) metabolite of hyoscyamine (27) and that the reaction proceeds via 6-hydroxyhyoscyamine [(—)-anisodamine (63)] and 6,7-dehydrohyoscyamine (211) (Scheme 26). 

Figure 2 Enantiomeric excess (%) as a function of the solvent polarity in the hydrogenation of tiglic acid using a CD-doped Pd/y-Al203 catalyst.

Table 1 Catalytic data for tiglic acid and other differently substituted oc,p-unsaturated acids.

Hydrogenation of tiglic acid in scC02 catalyzed by a chiral complex such as (136) (Scheme 68) proceeds cleanly with cis stereochemistry to afford 2-methylbutanoic acid in up to 89% ee and over 99% yield.367 These studies revealed a different influence of H2 pressure on the selectivity between liquid solvents and scC02. 

Thiolactic acid, m22 Thiomalic acid, m25 Thiosalicylic acid, ml8 Thiosinamine, a97 2-Thioxo-4-thiazolidinone, r7 Threonine, al85 Tiglic acid, ml69... 

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