O- aldehyde

HIYAMA - HEATHCOCK Stereoselectiveailylation Stereoselective synthesis o( anti homoaitylic alcohols by Cr promoted atlylation o( aldehydes. 

STILES - SISTI Fonnylatlon Synthesis o( aldehydes by (dnnylation o< Grignard reagents with p-dimethylaminobenzaidehyde and a (SazonKim salt. 

The product from phenoxide ion (64) is, after acidification, very largely the o-aldehyde (salicylaldehyde, 65) plus just a small amount of the p-isomer. If both o-positions in the initial phenoxide anion are substituted, however, reaction then yields the p-aldehyde. 

In addition to the expected o-aldehyde (68), it is also possible to isolate the unhydrolysed dichloro compound (69). Attack by CC12 at the p-position in (67c) yields the intermediate (70) which, unlike the intermediate for o-attack, has no H atom that can be lost, as H , to allow the ring to re-aromatise (70) thus just acquires a proton, on final acidification, to yield (69). The dichloro compound (69) owes its resistance to hydrolysis partly to its insolubility in the aqueous base medium, but also to the sterically hindered, neopentyl-type environment (cf. p. 86) of the chlorine atoms. 

Guaiacol, by the action of chloroform and alkali, gives vanillin in poor yield along with the o-aldehyde. 

Hydroformylation is an addition reaction of a hydrogen atom and a formyl group to an olefin to form two isomeric aldehyde products (Equation (1)). Both the aldehyde products are important chemicals //or///< /-aldehydes are industrially important because they are widely used for detergents and plasticizers the /i-o-aldehydes can be important intermediates for production of fine chemicals and drugs once the chiral center at the a-carbon to aldehyde is controlled. Progress in hydroformylation exactly traces that in the phosphine ligand chemistry and valuable aldehyde products have become available on an industrial scale. 

In contrast to the normal-scXcctwc hydroformylation mainly developed in industry, asymmetric hydroformylation, which requires /i o-aldehydes ( branched aldehydes) to be formed from I-alkenes, was first examined in the early 1970s by four groups independently, using Rh(i) complexes of chiral phosphines as catalysts. " Since then, a number of chiral ligands have been employed for asymmetric hydroformylation and used in combination with transition metal ions, especially Pt(ii) and Rh(i). Asymmetric hydroformylation of I-alkenes is most extensively studied. 

If methyleneindoline-o)-aldehydes are condensed with cyclic amines substituted by an amino group in the aromatic ring, dyes are obtained that can be dimerized either by reaction with cyanuric chloride in a molar ratio of 2 1 or with phosgene. On account of their high substantivity these dyes are suitable for dyeing bleached sulfite pulp [22],... 

Vogl, O., Aldehyde Polymers , in Encyclopedia of Polymer Science and Engineering, Wiley-Interscience, John Wiley Sons, New York, 1985, Vol. 1, pp. 623-643. 

Ttie exact po< ition of the equilibrium between a gem diot and a or aldehyde dependB on the structure of the carbonyl compound. Altii the equilibrium generaliy favors the less crowded carbonyl compound f stcnc reasons, the gem diot is favored for a few sinipl[Pg.762]

HIYAMA - HE ATHCOCK Stereoselectiveallytalion StereoMtoctive synthesis ot anti homoanyt ic alcohob by Cr promoted aRyiation o aldehydes... 

Synthesis o( aldehydes from pnmary aBcyl haUes or tosyiates. using dimethyl sulfoxide (OMSO). 

Ester. H II O Aldehyde, ketone (usually without a-hydrogens) Dehydration may follow... 

This reaction competes with intramolecular hydroacylation of pent-4-enals to form cyclopen-tanones. In the case of exo- and ent/o-norborn-5-ene-2-carboxaldehyde (4) if treated with Wilkinson s catalyst [tris(triphenylphosphane)rhodium(I) chloride] only decarbonylation occurs. While the exo-aldehyde exo-4 leads to norbornadiene (5), the e fi o-aldehyde endo-4 reacts to form nortricyclene (6 tricyclo[2.2.1.0 ]heptane). These results support organometallic pathways and exclude radical intermediates, since here identical products should be formed. 

Alken Sulfan [(,/o] Aldehyd Ausbeute [%] Lite- ratur... 

Ricinoleic acid Rosaniline Rosolic acid Saccharin Safrole (1-,3-,4-) (iso-)(l-,3-,4-j Salicylic acid (o-) aldehyde (o-)... 

HIYAMA - HEATHCOCK Stereoselectiveailytation Stereoselective synthesis of anti homoaDyl ic alcohols by Cr promoted aHylation o aldehydes. 

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