Pentynoic acid

The unsaturated c.vo-enol lactone 17 is obtained by the coupling of propargylic acetate with 4-pentynoic acid in the presence of KBr using tri(2-furyl)-phosphine (TFP) as a ligand. The reaction is explained by the oxypalladation of the triple bond of 4-pentynoic acid with the ailenyipailadium and the carbox-ylate as shown by 16, followed by reductive elimination to afford the lactone 17. The ( -alkene bond is formed because the oxypalladation is tnins addition[8]. 

PdCb, and the allylated lactone 232 is formed. Regeneration ofPdCl2 as shown by 231 makes the reaction catalytic. In this reaction, use of the Li salt 227 of 4-pentynoic acid (223) is recommended. Reaction of lithium 3-octynoate (233) with allyl chloride affords the unsaturated lactone 234, which is converted into the 7-keto acid 235 by hydrolysis[126]. 

The optically active Trogoderma -pheromones ( )- and (Z)-24have been synthesized starting from (5)-citronellol and 4-pentynoic acid [192], Alkatrienes 25, sex attractants of Lepidoptera, were prepared by mixed Kolbe electrolysis with linolenoic acid [193], 26, the pheromone of the German cockroach Blattela Germanica has been prepared from 3-methylheneicosanoic acid [194], ( ) — Tuberculostearic acid (27) has been... 

The Pauson-Khand reaction is the Co-induced formation of cyclopentenones from ene-ynes and CO. One impressive example of a domino Pauson-Khand process is the synthesis of fenestrane 6/4-15, as reported by Keese and colleagues [278]. The transformation is initiated by a double Grignard reaction of 4-pentynoic acid 6/4-12, followed by protection of the formed tertiary hydroxyl group to give 6/4-13. The Co-induced polycyclization of 6/4-13 led directly to the fenestrane 6/4-15... 

Figure 17.15 The small carboxylate-alkyne compound 4-pentynoic acid can be used to modify proteins at their amine groups with EDC to provide alkyne sites for click chemistry-mediated conjugation. The subsequent reaction of an azido-PEG-modified gold nanoparticle with the alkynyl-protein in the presence of Cu1+ yields the triazole-coupled protein.

Prepare a stock solution of 4-pentynoic acid by dissolving it at a concentration of 100 mM in 50 percent THF/PBS. Add 6.7 pi of this solution to the protein solution with mixing. 

The process is initiated by a double Grignard reaction of 4-pentynoic acid 153, first with 3-butenyl magnesium bromide and subsequently magnesium acetylide followed by silylation of the formed ter-tiaiy hydroxyl function. The cobalt induced polycy-clization leads directly to the fenestrane 157 interestingly, the reaction halts at the stage of 156 when employing the unprotected alcohol. 

Pentynoic acid, 5 34t People. See also Personnel investment in, 21 624 organizational ties to, 21 627-628 People s Republic of China. See also China demand for oil in, 23 530 oil recovery program in, 23 534 Pepper, pipeline levels in, 23 159 Peptide antibiotics, 18 252-253. See also Antimicrobial peptides Peptide backbone hydrogen bonds, in proteins, 20 826 Peptide mapping, 3 840-841 Peptide nucleic acids, 17 631-634... 

The Pd-catalyzed coupling reaction of the propargyl acetate 53 and 4-pentynoic acid (54) in the presence of potassium bromide produced the unsaturated exo-enol lactone 55 [66], The reaction proceeded via oxypalladation of the triple bond of 54 with an allenylpalladium intermediate, which was formed from Pd(0) and 53 and the carboxylate as shown in Scheme 3.30. 

Propylpentanoic acid (valproic acid) (12) contains no chiral centers, but one of its mammalian metabolites is 2-propyl-4-pentenoic add (14), which has a chiral center at C-2. (S)-2-Propyl-4-pentenoic acid is a much more potent teratogen, at least in some assays, than (R)-2-propyl-4-pentenoic acid [56]. Similar observations have been made for the specific enantiomers of 2-propyl-4-pentynoic acid (15). (S)-2-Propyl-4-penty-noic acid is a much more potent teratogen than (R)-2-propyl-4-pentynoic acid [57]. 

While 4-pentynoic acid reportedly yields the geminal diiodide (equation 146),165 2-alkynoic acids generally produce almost exclusively the 3-iodo-2-alkenoic acids of anti addition (equation 147).97,98 191... 

Chemical Name (3S)-3-[[4-[[4-(Aminoiminomethyl)phenyl]amino]-l,4-dioxobutyl]amino]-4-pentynoic acid ethyl ester monohydrochloride... 

In the attempt to petform hydroacylation on 4-pentynoic acid using Wilkinson s catalyst in the presence of various aminopyridines, a method for the stereoselective synthesis of ( )-alkylidene derivatives of (3//)furan-2-ones has been discovered (Equation 44) <2005SL1113>. 

These spacer-free Janus bis-carbene complexes were successfully employed in the intramolecular cyclisation of acetylenic carboxylic acids (4-pentynoic acid and 5-hexynoic acid) as well as the transfer hydrogenation of ketones and imines. 

Scheme 11.47 Formation of unsaturated exo-enol lactone from 4-pentynoic acid.

The adducts are useful for preparation of alkylated amino acids. An example is the preparation of 2-amino-4-pentynoic acid (4) from ethyl glycinate (3). 

Amino-4-pentynoic acid, 140 Aminopyrimidines, 157 Ammonia-borane, 12 Androstanes, 371, 372 Anethole, 223 2,5-Anhydro-D-gludtol, 357 Anilines, 48... 

The translational activity of various unsaturated analogs of L-isoleucine was evaluated using an Escherichia coli strain auxotrophic for isoleucine. It was observed that the alkene [2-amino-3-methyl-4-pentenoic acid (2)] and alkyne [2-amino-3-methyl-4-pentynoic acid (3)] derivatives of L-isoleucine can support protein synthesis at levels approximately 50% of that observed in cultures supplemented with isoleucine. However, no incorporation of the ocC or /JC methylated derivatives could be detected. In order to examine the stereoselectivity of incorporation, the (2S, 3S) and (2S, 3R) diastereomers of 2 and 3 were prepared. The extents of isoleucine substitution in vivo were 80% and 70% for (2S, 3S)-2 and (2S, 3S)-3, respectively, under the conditions examined in this study. 

Diastereomers mixtures (Figure 1) of 2-amino-3-methyl-4-pentenoic acid (2), 2-amino-2-methyl-4-pentynoic acid (21), 2-amino-3-dimethyl-4-pentenoic acid (22), 2-amino-2,3-dimethyl-4-pentenoic acid (23), 2-amino-3-methyl-4-pentynoic acid (3), 2-amino-3-dimethyl-4-pentynoic acid (31), 2-amino-2,3-dimethyl-4-pen-tynoic acid (32) were prepared according to Aidene et al.tl The regioselective reaction between a-unsaturated organozincs and A-(phenylsulfanyl)iminoesters was used as a starting step to obtain the a-aminoesters.11... 

Pentynoic acid Propargylacetic acid C5H6O2 6089-09-4 98.101 67.7 110 ", 1021 vs eth, EtOH... 

Methylene-y-btttyrolactone (3). An efficient route to this lactone (also known as a -angelicalactone) involves oxidation of 4-pentyne-l-ol (1, Chem. Samples) to 4-pentynoic acid (2) followed by cyclization with mercuric acetate. ... 

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