18-Aldehyde group, introduction

Formylamines s. Formamides C-Formyiation (s. a. C-Hydroxy-methylenation, Aldehyde groups, introduction) 20, 600 —, o-formylation, preferential, of phenols 20, 558 N-Foriiiylation... 

Formylamines s. Formamides C-Formylation (s. a. Hydroxy-methylene. . ., Aldehyde group, introduction) 16, 797 N-Formylation, preferential 16, 421... 

Osmium tetroxide used in combination with sodium periodate can also effect alkene cleavage.191 Successful oxidative cleavage of double bonds using ruthenium tetroxide and sodium periodate has also been reported.192 In these procedures the osmium or ruthenium can be used in substoichiometric amounts because the periodate reoxidizes the metal to the tetroxide state. Entries 1 to 4 in Scheme 12.18 are examples of these procedures. Entries 5 and 6 show reactions carried out in the course of multistep syntheses. The reaction in Entry 5 followed a 5-exo radical cyclization and served to excise an extraneous carbon. The reaction in Entry 6 followed introduction of the allyl group by enolate alkylation. The aldehyde group in the product was used to introduce an amino group by reductive alkylation (see Section 5.3.1.2). 

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... 

Water colloid solutions of fullerenes C60 (10 4 M) were prepared as described in Scharff et al. (2004). Fullerene-aminopropylaerosyl (fullerene C60-composite-l) was synthesized (Golub et al., 2003) by the introduction of aminopropyl chains oriented ad extra by amine groups (0.9 mM/g), to the surface layer of sihcon dioxide nanoparticles that were bound to fullerene C60 (0.12 mM/g) (Fig. 6.1). Fullerene-anthracenaliminopropylaerosyl (fullerene C60-composite-2) was composed also from anthraccnaliminc (0.2mM/g) that was introduced via azomethine condensation of aldehyde group of anthracenal with surface amino group. 

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... 

The acetylacetonates of chromium, cobalt, and rhodium were found to react with dimethylformamide in the presence of phosphorus oxychloride to yield formyl-substituted chelates (10). This is a well known technique for the introduction of an aldehyde group into reactive aromatic systems. The formylation of the chelate rings is a slow reaction, and by controlling the conditions it is possible to... 

The aldehyde functional group is a very reactive functional group thus methods to prepare it must be mild and allow the aldehyde group to survive the reaction conditions. Traditional methods for introduction of the aldehyde functional group include... 

The anion derived from the 1,3-dithiole 367 reacts with thioxanthone to give the 9-(l,3-dithiol-2-ylidene)thiox-anthene derivative which is a 7t-electron donor system. The introduction of a benzaldehyde unit at the 4-position of the dithiole ring was achieved by iodination and a Pd-mediated cross-coupling with 4-formylbenzeneboronic acid. The aldehyde group allowed attachment to C(,o via a 1,3-dipolar cycloaddition of an azomethine ylide (Scheme 87) <2005JMC1232>. 

These reactions do not by any means cover the whole field, but represent only the more important portions of it Later in this book, other less important reactions are mentioned, such as alkylation of amines, introduction of the aldehyde group by die Sandmeyer method, and phenylation. Although some of these reactions are carried out on a large scale, especially in die preparation of alkyl- and benzylanilines and toluidines, they are in terms of quantity of considerably less importance than the operations discussed above. 

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

There are several methods for the direct introduction of an aldehyde group into an aromatic compound. In the Vilsmeier-Haack reaction, activated aromatic systems such as aryl ethers and dialkylanilines are formylated by a mixture of dimethylformamide, HCONMe2, and phosphorus oxychloride, POCL, (Scheme 6.4). The process involves elec-trophilic attack by a chloroiminium ion, Me2N=CHCl, formed by interaction of dimethylformamide and phosphorus oxychloride. Hydrolysis of the dimethyl imine completes the synthesis. 

Reimer-Tiemann Reaction. —Both the ortho- and para-hydroxy benzaldehydes are important. They may both be synthesized by what is known as the Reimer-Tiemann reaction. This consists of the interaction between a salt of a phenol and chloroform in the presence of an excess of alkali. The result is the introduction of the aldehyde group, (—CHO), into the benzene ring of the phenol as follows ... 

---