A- propionic

The Stobbe condensation thus provides a method for introducing a propionic acid residue at the site of a carbonyl group. 

The tetramerization of suitable monopyrroles is one of the simplest and most effective approaches to prepare porphyrins (see Section 1.1.1.1.). This approach, which is best carried out with a-(hydroxymethyl)- or ot-(aminomethyl)pyrroles, can be designated as a biomimetic synthesis because nature also uses the x-(aminomethyl)pyrrole porphobilinogen to produce uroporphyrinogen III. the key intermediate in the biosynthesis of all kinds of naturally occurring porphyrins, hydroporphyrins and corrins. The only restriction of this tetramerization method is the fact that tnonopyrroles with different -substituents form a mixture of four constitutionally isomeric porphyrins named as porphyrins I, II, III, and IV. In the porphyrin biosynthesis starting from porphobilinogen, which has an acetic acid and a propionic acid side chain in the y6-positions, this tetramerization is enzymatically controlled so that only the type III constitutional isomer is formed. 

Phenyl(3-a -"ethylpropionate ), 4-carboxamide] -tetrazanetll. Note a-ethylpropionate (or more correctly, in the opinion of the editor, a-ethylpropionatyl) is the proper name for the radical —CH(CH3).CCfe-C2H5, derived from a-propionic acid ethyl ester. (C6H5).N N.N[CH(CH3).C02.C2H5].NH(C0.NH2), mw 279.34, N 25.08%, crysts from aq ale, mp (melts with expln ca 125°)... 

In contrast to oxoesters, the a-protons of thioesters are sufficiently acidic to permit continuous racemization of the substrate by base-catalyzed deprotonation at the a-carbon. Drueckhammer et al. first demonstrated the feasibility of this approach by performing DKR of a propionate thioester bearing a phenylthiogroup, which also contributes to the acidity of the a-proton (Figure 4.14) [39a]. The enzymatic hydrolysis of the thioester was coupled with a racemization catalyzed by trioctylamine. Owing to the insolubility of the substrate and base in water, they employed a biphasic system (toluene/H2O). Using P. cepacia (Amano PS-30) as the enzyme and a catalytic amount of trioctylamine, they obtained a quantitative yield of the corresponding... 

A ci positional state where the exposed NeH group of His 161 which is a ligand of the Rieske cluster forms a hydrogen bond with a propionate group of heme Ci (42)... 

In the ci positional state, fast electron transfer from the Rieske protein to cytochrome Ci will he facilitated hy the close interaction and by the hydrogen bond between His 161 of the Rieske protein and a propionate group of heme Ci, but the Rieske cluster is far away from the quinone binding site. 

FIGURE 17.23 2D contour plot of a propionic acid modified polyamide 6.6 (assignments according to Table 17.1), first dimension LCCC, second dimension MALDI-TOF. (See color plate.)... 

Heppner, B., Zellner, G., and Diekmann, H., Start-Up and Operation of a Propionate-Degrading Fluidized-Bed Bioreactor, Appl. Microbiol. Biotechnol., 36 810 (1992)... 

BODIPY 530/550 C hydrazide is 4,4-difluoro-5,7-diphenyl-4-bora-3a,4a-diaza-s-indacene-3-propionyl hydrazide, a derivative of the basic BODIPY structure that contains two phenyl rings off the No. 5 and 7 carbon atoms and a propionic acid hydrazide group on the No. 3 carbon... 

Since dienolates 1 and 2 represent diacetate synthons, the dienolate derived from 6-ethyl-2,2-dimethyldioxinone can be seen as a propionate-acetate syn-thon. The synthesis of the corresponding dienolate provides a mixture of the E and Z enolates in a 3 5 ratio. The reaction with Ti-BINOL complex 5 generates a 5 1 mixture with the syn isomer as the major diastereomer. After separation of the diastereomers, the enantiomeric excess of the syn isomer was determined to be 100%. The anti isomer was formed in 26% ee. The same transformation performed with boron Lewis acid 7 gave the anti isomer as the major compound, but only with 63% ee. The minor syn isomer was produced with 80% ee. The observed selectivity could be rationalized by an open transition state in which minimization of steric hindrance favors transition state C (Fig. 1). In all three... 

The other acetogenins, shown in Table II, are a varied assortment of small molecule compounds which as a group contain alkene, alcohol, and carbonyl (acid, ester, aldehyde, and ketone) functionality. They are fairly typical substances with common structural features. Again, those compounds possessing an odd number of carbon atoms are less common, and biogenetlcally may be derived from a propionate starter unit. 

Indometacin is an indole acetic acid derivative, while naproxen is a propionic acid derivative. Both are non-steroidal anti-inflammatory drugs (NSAIDs). Indometacin is associated with a higher incidence of side-effects, particularly gastrointestinal as well as headache and dizziness. 

Naproxen is a non-steroidal anti-inflammatory agent classified as a propionic acid derivative. 

The 1 1 complex of the tris-A-propionate derivative of 1,4,7-triazacyclononane has been synthesized and X-ray diffraction has confirmed that all ligand donors are bound to the manganese(III) ion surprisingly there was no evidence for a Jahn-Teller distortion of the type expected for a high-spin rf system of this type." ... 

Horse radish peroxidase on the other hand, is a hemoprotein which is inhibited by alkylation of the porphyrin ring 48 by a -propionic acid radical resulting from the ring cleavage of the cyclopropanone hydrate 21, providing the car-boxylate 49,Eq. (17). 

Estrone, or l,17p-Dihydroxy-4-methylestra-1,3,5(10)triene 3-(l-Oxo-8p-methyl-5p-carboxy-trans-perhydroindanyl-4 a)propionic acid C [248]... 

A fluorinated analogue of meio-bilirubin, a biliary pigment, has been prepared from a pyrrole bearing a propionic chain on which the fluorine has been introduced with DAST reagent by reaction with hydroxyl of the lactic lateral chain. The presence of fluorine modifies the spectral properties and the solubility (Figure 4.30). °... 

NSAIDS and a Statin . Benzene rings provide the aromatic nucleus for the majority of the NSAIDs. A propionic acid attached at its 2 position provides the side chain for most of these compounds, as noted in Chapter 2. Inhibition of the cyclooxygenase enzyme and consequently NSAID activity is retained when the role of an aromatic ring is filled by a pyrrole. The side chain for all but one of those compounds, it should be noted, consists of an otherwise unsubstituted acetic acid. 

Flurbiprofen is a propionic acid derivative with a possibly more complex mechanism of action than other NSAIDs. Its (S)( ) enantiomer inhibits COX nonselectively, but it has been shown in rat tissue to also affect tumor necrosis factor- (TNF- ) and nitric oxide synthesis. Flepatic metabolism is extensive its (R) +) and (S) ) enantiomers are metabolized differently, and it does not undergo chiral conversion. It does demonstrate enterohepatic circulation. 

Ketoprofen is a propionic acid derivative that inhibits both COX (nonselectively) and lipoxygenase. Its pharmacokinetic characteristics are given in Table 36-1. Concurrent administration of probenecid elevates ketoprofen levels and prolongs its plasma half-life. 

Table 4 was unity, which indicated the five-coordinate structure as in the PVMI-heme complex. PBLGIm forms an a-helix, and the helix content and intrinsic viscosity were unchanged in the PBLGTm ferriheme complex. The formation constant of the ferriheme complex with PBLGTm was not so different from that of the imidazole complex (Table 4). The strong coordination was thought to be due to an additional hydrogen bond between a propionic residue of ferriheme and a carbonyl residue in the side chain of PBLGTm, as shown in Fig. 4(d)w ...

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