Transformations propionic acid

This was transformed into the quaternary d-bromocamphorsulphonate, m.p. 265°, but no resolution has yet been effected. The lactam of 3-carboxyhexahydrocarbazole-1 ll-)3 8 -dipropionic acid (XXIV, with a carboxyl group at C ), CigH jO N, rn.p. 257-8°, has also been prepared. The same authors, with Holmes, have synthesised the lactam of 11-ethylhexahydrocarbazole-l-)3-propionic acid, Ci,H3iON, m.p. 106-8-107-5°, of which (XXrV) is a carboxy-derivative. 

Parallel ketonization of acetic acid and propionic acid was one of the transformations of this type studied in our Laboratory. Ryba6ek and Setinek (94) investigated the kinetics of these reactions in the gaseous phase at 316°C using thorium oxide on activated carbon (p. 27) as the catalyst. This model system allowed the study of each reaction separately as well as of the simultaneous conversion of both acids. 

Only the R(+) enantiomer of the herbicide 2-(2-methyl-4-chlorophenoxy)propionic acid was degraded (Tett et al. 1994), although cell extracts of Sphingomonas herbicidovorans grown with the R(-) or S -) enantiomer, respectively, transformed selectively the R -) or S(-) substrates to 2-methyl-4-chlorophenol (Nickel et al. 1997). 

In addition to methanogens and some acetogens, bacteria capable of 1,2-propanediol fermentation have been reported to produce vitamin B12 [286]. The transformation of 1,2-propanediol (propylene glycol) to propionaldehyde requires vitamin B12. Further fermentation of propionaldehyde to n-propanol and propionic acid does not require vitamin B12 but yields energy for growth. 

A heterocyclic amino acid, 3-amino-3-(3 -thienyl)propionic acid, when treated with TFA and TFAA, is transformed under severe reaction conditions into compound 59 (86TL2607). 

Propionic Acid. The Reppe reaction is used to transform ethylene, carbon monoxide, and water to propionic acid.82 [Ni(CO)4] is formed in situ from nickel salts under reaction conditions (270-320°C, 200-240 atm). The addition of halogens and phosphine ligands allows milder reaction conditions (Halcon process, 170-225°C, 10-35 atm). Propionic acid yields are around 95%. 

In almost all of the transformations described above it has been assumed that both vinyl groups of protoporphyrin-IX (19) have been affected. Obviously, by judicious control of stoichiometry it is possible in many cases to effect only partial transformations of protoporphyrin-IX in which only one vinyl group has been modified. Under these circumstances a mixture of the 3-vinyl and 8-vinyl derivatives results, and in a number of situations these isomers can be isolated, separated and characterized. In order to purify almost all of the compounds shown in Scheme 8, it is usually necessary to esterify the propionic acid groups on the 13- and 17-positions so that the products can be effectively chromatographed, usually on alumina or silica. Indeed, in many instances the reactions are carried out on the dimethyl ester derivatives, and this enables normal organic solvents to be employed. 

Claisen condensation of ethyl quinuclidine-2-carboxylate (73) with ethyl acetate yields ethyl j8-oxo-j8-(2-quinuclidyl)propionate (84). This was transformed into j8-amino-j3-(2-quinuclidyl)propionic acid (85)108 and 2-acetylquinuclidine (86).43... 

Similarly, 3-forinylquinuclidine (76) was transformed into /3-(quinuolid-3-yl)acrylic (97) and propionic acids (98).140... 

The alkylation products are synthetically useful because simple subsequent transformations furnishes precursors of important natural products as illustrated in Scheme 8E.23. Simple oxidative cleavage of allylic phthalimide 45 generates protected (5)-2-aminopimelic acid, whose dipeptide derivatives have shown antibiotic activity. The esterification via deracemization protocol is not limited to the use of bulky pivalic acid. The alkylation with sterically less hindered propionic acid also occurs with high enantioselectivity to give allylic ester 116, which has been utilized as an intermediate towards the antitumor agent phyllanthocin and the insect sex excitant periplanone. Dihydroxylation of the enantiopure allylic sulfone gives diol 117 with complete diastereoselectivity. Upon further transformation, the structurally versatile y-hydroxy-a,(f-un-saturated sulfone 118 is readily obtained enantiomerically pure. 

Often (e.g. in asymmetric synthesis) one is interested in the fact that in certain molecules, such as propionic acid (2, Fig. 1), an achiral center (here C ) can be transformed into a chiral center by replacement of one or other of two apparently identical1 ligands2 by a different one. Thus the replacement of HA at C in propionic add (Fig. 1) by OH generates the chiral center of (lactic acid. C in propionic acid is therefore called a prochiral center 4) HA and HB are called heterotopic ligands 5 7) (from Greek heteros = different and topos" = place — see also below). Prochiral axes and planes may similarly be defined in relation to chiral axes and planes (see below)... 

Crystallization-induced asymmetric transformation has already been described by Leuchs in 1913 during the resolution of 2-(2-carboxybenzyl)-l-indanone with brucine.34 In this case spontaneous racemization occurred. More recently researchers at Sanofi observed spontaneous racemization during the resolution of 3-cyano-3-(3,4-dichlorophenyl)propionic acid (7), most likely as a result of the basic resolving agent [>-(-)-N-1 n etli y I g I near nine [d-(-)-MGA] (8) (Scheme 7.6).35 The enantiopure cyano acid, obtained in 91% overall yield, is subsequently reduced to (+)-4-amino-3-(3,4-dichlorophenyl)-l-butanol (9), a key intermediate in the phase 2 synthesis of tachykinin antagonists. 

Other routes to MMA start from ethylene, propylene or propyne and involve metal catalysis at some stage of multi-step transformations for example by the hydroformylation of ethylene to intermediate propionaldehyde, oxidation to propionic acid, followed by condensation with formaldehyde. The Pd-catalyzed carbonylation of propyne to MMA is a further method. However only the ethylene route has found some industrial application (see Chapter 4, Section 4.3.1). 

The condensation of the dilithio derivative of (R)-(+)-3-(p-tolylsulfinyl)propionic acid with protected glycoaldehy-des (O-r-butyl and 0-benzyl) gives 5-alkoxy-4-hydroxy-3-(p-tolylsulfinyl)pentanoic acids, which spontaneously cyclize to the corresponding 3-sulfinyl-4-alkoxymethyl butanolides (eq 4). Pure diastereomers can be separated by flash chromatography and are obtained in comparable amounts. The corresponding optically pure butenolides are obtained by pyrolytic elimination of the sulfoxides and then transformed into natural (-i-)-(/ )-umbelactone (eq5). 

While caoutchouc was first obtained by polymerizing isoprene it has been found that other hydrocarbons containing the buta i-ydi-ene group will likewise yield caoutchouc. Such hydrocarbons have been obtained from several sources, e.g., turpentiney petroleuniy coaly acetylene. Also compounds related to succinic acid, e.g., pyrotartaric acid (methyl succinic acid) are possible of transformation into isoprene. Levulinic acid, which is aceto propionic acid, CHa—CO—CH2—CH2—COOH, yields a cyclic sulphur compound, methyl-thiophen (p. 853), which, like methyl pyrrolidine, yields isoprene. Ethyl alcohol by conversion into acetone and then by aldol condensation with ethane yields 2-methyl buta 2-ene, CHa—C = CH—CHa which may be transformed... 

The cyanomethyl-substituted pyrido[2,l-i ]quinazolinones 211 (R = CH2CN) can be transformed by chain elongation into the propionic acid and propionic acid ester derivatives. Reactions were effected by heating the cyanomethyl derivatives for 2 hr in diethyl carbonate in the presence of sodium hydride, followed by evaporation and treatment with methyl iodide and sodium hydride in dimethylformamide at 0°C, and finally by stirring of the evaporated oily residue in a mixture of isopropanol and coned, sodium hydroxide to obtain the acids,and in 0.5 N aqueous acetic acid to obtain the esters. ... 

This reaction was often used to transform primary heterocyclic amines to imino esters. The following selection of more recent examples will demonstrate the range of the method. Orthoesters of formic acid, acetic and propionic acid have been reacted with substituted... 

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