Introduction of aldehydes

We have developed an efficient and practical method for clean oxidation of starch (21-23) resulting in the oxidation of primary alcohol function in Ce position and the cleavage of vicinal diols in C2 and C3 position (Figure 30.2). We used small amounts of cheap iron tetrasulfophthalocyanine catalyst, pure water as reaction medium and H2O2 as clean oxidant to achieve a one-pot conversion of starch resulting in the introduction of aldehyde and carboxyl functions in polymer chains. The iron content... 

Alternatively, the acetaldehyde may be distilled into the flask through the nitrogen inlet. During this operation, the outlet must be kept well above the surface, to prevent clogging. The introduction of aldehyde is stopped when the red color has disappeared. 

In Table 15 are recorded the dissociation constants of certain phenolic compounds. From these data it becomes obvious that the introduction of aldehyde groups, or other substituents, changes the dissociation constant of phenolic hydroxyls by over one-hundred fold. Moreover, oxidation studies carried out in this laboratory have shown that the native lignins from bagasse, white Scots pine and birch contain... 

Treatment of polystyrene particles with dialdehyde caused the introduction of aldehyde groups onto the particles (3). The aldehydes are used as binding sites for functional compounds. Carboxyl groups on particles are also in common use as a... 

Fig. 48 Introduction of aldehyde functions by conversion of 3-chloro-2-hydroxypropyl dextran (activated dextran) with hydroxybenzaldehyde A or carboxybenzaldehyde (A, lower part, B)...

Introduction of aldehyde groups 2-Chloro-4-dimethylaminobenzaldehyde from m-chlorodimethylaniline,... 

Fetuin. — After introduction of aldehyde groups at C-7 of neuraminic acid residues in fetuin, an amine-containing spectroscopic probe has been attached to the molecule by reductive amination. The spin-label has also been introduced into asialofetuin after modification of the glycoprotein with either D-galactose oxidase or sodium periodate. 

Mucins. — Bovine submaxillary mucin and its asialo-derivative have been spin-labelled after introduction of aldehyde groups as described for fetuin. ... 

Perchlorobutyryl chloride Introduction of aldehyde groups into ar. rings... 

Proudnikov et al. [17] presented a preparation method based on the introduction of aldehyde groups by partial depurination of DNA or oxidation of the 3 -terminal ribonucleoside in RNA by sodium periodate. We have routinely used this method to couple fluorescent dyes with attached hydrazine groups to the aldehyde groups. This bond is then stabilised by reduction. 

Scheme 1.17 Introduction of aldehyde functionalities using vicinal hydrojg l groups of polysaccharides.

N-alkylation with — 18, 397 —, introduction of aldehyde groups with — 18, 831... 

This allylation protocol was used in the total synthesis of amphidinolide to give homoallylic alcohol 12 in 72% yield and 17 1 dr (eq 5). Initial transmetallation of stannane 10 with (R,R)-1 via allylic transposition yielded an intermediate borane. Introduction of aldehyde 11 at -78 °C provided for a facile condensation reaction leading to 12. Stereocontrol was induced from the 1,2-diphenylethane sulfonamide auxiliary and could be predicted from a Zimmerman-Traxler model with minimized steric repulsions. The high level of selectivity obtained in this case was a result of a matched diastereomeric transition state featuring the inherent Felkin-Ahn selectivity for nucleophilic attack in aldehyde 11, with the (5)-configuration of the benzoate of 10, as well as the (7 ,7 -antipode of auxiliary 1, resulting in threefold stereodifferentiation. 

Introduction of aldehyde groups with a,a-didbloroniethyl ether... 

Fig. 15.5 Bioconjugation methods for VNPs. (A) An overview of the three most common bioconjugation chemistries, Lys-NHS, Cys-maleimide, and carbodiimide. (B) Diazonium coupling chemistry. (C) Oxidative coupling to the unnatural amino acid p-aminophenylalanine. (D) Condensation reactions to form oximes and hydrazones, two strategies for the introduction of aldehydes into proteins and bioorthogonal condensation reaction.

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