Enhancer Formyl group

Adjacent formyl groups facilitate the hydrolysis of certain aromatic esters, as illustrated by the examples below. Indicate a mechanism for this rate enhancement. ... 

The type of inhibition of chicken intestine alkaline phosphatase by forphenicine was not competitive, but uncompetitive with the stibstrate. Its derivative, forphenicinol, which contains a hydroxymethyl grorp instead of the formyl group in the forphenicine molecule, did not inhibit alkaline phosphatase but, it did bind to cells. Forphenicinol enhanced delayed-type lOT>ersensiti-vity (13,14) and the phagocytic activity of macrophages. 

Simple formyjgmethionyl peptjge stimulate leukocyte movement and are chemotactic. Becker et al have synthesized a series of di-, tri-, and tetrapeptides, most of them being formyl methionyl peptides. These are chemotactic, stimulate phagocytosis of latex particles, and cause the selective release of lysosomal enzymes from PMN in the presence of cyto-chalasin B. There is a high degree of correlation between the ability of the peptides to enhance PMN movement and cause selective release of acid hydrolases. The presence of the formyl group on the methionine leads to a 3,000- to 30,000-fold increase in chemotactic activity. Further studies... 

By attaching formyl groups [106] and reducing them to hydroxymethyl moieties, benzylic alcohol functions can be formed [108], which enhances the polymerization rates when used with epoxides in Brpnsted-acid-catalyzed ring-opening cationic polymerizations. As termed by Penczek and Kubisa, the polymerization follows a mechanism called the activated monomer mechanism (Scheme 11.29) [109-112],... 

PF-3>PF-l>saccharose)p-CD)none. Here the effect of molecular weight on the rate enhancement was also observed. Dextrose was unsuitable as a matrix because it underwent a side reaction during polycondensation, which was caused by the reaction of formyl group with amine. Presumably, an aldehyde group in dextrose may react with HMD to form a Schiff base. Figure 4 shows time-conversion curves of the polycondensation of DMT with HMD in the presence of PF at various concentrations of monomer.. Rate enhancement due to the PF matrices decreased in proportion to the increase in the molar ratio of monomer to PF matrix. 

DFT-based mechanistic studies and free energy computations have explained why enhanced rates of MBH reactions of heterocyclic aldehydes depend on the position of a formyl group. ... 

Steric effects of the hexacarbonyldicobalt moiety may be responsible for altered reactivity, notably enhanced stereoselectivity in reactions of adjacent substituents, e.g. formyl groups in aldol condensations. Thus, condensation of trimethylsilylpropy-nal with the silyl enol ether of cyclopentanone gives a 90% yield of the aldol product (eq 50) as a 40 60 erythro threo mixture, whereas reaction of the Co2(CO)6-complexed aldehyde followed by cerium(IV) oxidation gives the same total yield, but in an 87 13 diastereomeric ratio. ... 

The first observation of a significant rate enhancement in the alkaline hydrolysis of an ester by a suitably positioned carbonyl group that was related to prior attack of hydroxide at the carbonyl group was made in 1955 (Djerassi and Lippman, 1955). However, in 1962, a more detailed mechanistic pathway was suggested which involved attack by hydroxide at an o-formyl or benzoyl group, followed by intramolecular nucleophilic attack on a benzoate ester (Newman and Hishida, 1962 Bender and Silver, 1962). 

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