O-Hydroxyaldehydes

Schiff s bases formed from o-hydroxyaldehydes often form reagents of service in analysis. For example, the base formed with ethylenediamine forms an insoluble complex with nickel (14) which has been used for its gravimetric determination. 2-(o-Hydroxyphenyl)benzoxazole (15a) has been... 

Cesium antimony (III) chloride, 3CsCl-2SbCls, precipitation in extraction of cesium from pollucite, 4 6 Cesium azide, 1 79 Cesium dibromoiodate(I), 5 174 Cesium dichloroiodate(I)(iodo-dichloride), 4 9 5 174 analysis of, 4 11 Cesium diiodoiodate(I), 5 174 Cesium nitrate, 4 6 1-hydrogen nitrate, 4 7 Cesium titanium alum, 6 50 Charcoal, sugar, 2 74 Chelate compounds, of 1,3-diketones, 2 11 5 105 of o-hydroxyaldehydes and o-hy-droxyphenones, 2 11... 

The estrogenic properties displayed by isoflav-3-ene derivatives have attracted the attention of medicinal chemists. Varma et al. have discovered a facile and general method for the microwave-assisted synthesis of isoflav-3-enes substituted with basic moieties at the 2-position (Scheme 14) [69]. This convergent approach exploits in situ generated enamine derivatives that are subsequently reacted with o-hydroxyaldehydes in the same pot. 

As mentioned in the introduction, the synthesis of low molecular N202-chelates as Co(sa-len) (6) is rather easy when starting from salicylaldehyde, diamines and a metal salt. For the polymer synthesis only bifunctional o-hydroxyaldehydes must be used. The limiting factor for practical use of polymers may be the price of the bifunctional monomer. The difficulty in preparation is to get a structurally pure polymer and to reach quantitative metallization. 

N20rchelates (737), (733) with an open bridge were prepared by reaction of bifunctional o-hydroxyaldehyde derivatives (730), (732) with metal salts in DMF or ethanol (Eq. 66, 67) >297,298)... 

An interesting application of the method by Jeger s group d is to 8a,20-oxido-manool (5). On oxidation in aqueous dioxane the initially formed o-hydroxyaldehyde (6) suffered reverse aldolization to give the methyl ketone (7) and formaldehyde. 

The cyanine salt 27 is obtained by treatment of the quinoxalinium perchlorate 26 in pyridine with triethylorthoformate, and as expected the corresponding methylsulfate (28) is found to undergo ready condensation with aromatic aldehydes Reaction of 28 with o-hydroxyaldehydes yields spiropyrans such as 29. " 1-Acetoxyquinoxalinium perchlorates of... 

The following bifunctional o-hydroxyaldehydes (123) and diamines (124) were used to prepare at first the polymer ligand (125), (126). The introduction of metal ions like... 

A third approach for the synthesis of polymeric Schiff-base chelates is to prepare at first in situ a precursor chelate of the diamine and a M(II), or an o-hydroxyaldehyde and a M(I1), and to add then the second component o-hydroxyaldehyde, or a diamine [1,14,15], respectively. 

Ring closures with isocyanates 3,4-Dihydro-4-hydroxy-2H-l,3-benzoxazin-2-ones from o-hydroxyaldehydes and isocyanates... 

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