Aldehydes Reimer-Tiemann synthesis

There are, in addition, a number of methods by which the aldehyde group is introduced into an aromatic ring for example, the Reimer-Tiemann synthesis of phenolic aldehydes (Sec. 24.12). 

Phenolic aldehydes can be obtained by the Duff reaction, in which the phenol is heated with urotropine, boric acid, and glycerol for 30 minutes at 150-160° 857 the yields are not high (15-20%), but the procedure is simpler and less time -consuming than the Reimer-Tiemann synthesis the products are the ortho-derivatives. Dialkylanilines can be formylated in the same way,858 but here the products are the para-aldehydes. 

The formylation of a phenol 1 with chloroform in alkaline solution is called the Reimer-Tiemann reaction. It leads preferentially to formation of an ortho-formylated phenol—e.g. salicylic aldehyde 2 —while with other formylation reactions, e.g. the Gattermann reaction, the corresponding /jara-formyl derivative is obtained as a major product. The Reimer-Tiemann reaction is mainly used for the synthesis of o-hydroxy aromatic aldehydes. 

Crafts alkylation and acylation (Section 22-4E and 22-4F), the Gattermann-Koch reaction for preparation of aldehydes from arenes and carbon monoxide (Section 22-4F), and the Kolbe-Schmitt, Reimer-Tiemann, and Gattermann reactions for synthesis of acids and aldehydes from arenols (Section 26-1E). 

From Phenols by CCI4.—The Reimer-Tiemann reaction for the synthesis of hydroxy aldehydes (p. 659) is ... 

Reimer-Tiemann reaction. Synthesis of phenolic aldehydes. Dichlorocarbene... 

M.E. Jung and co-workers have developed a synthesis of selectively protected L-Dopa derivatives from L-tyrosine via a Reimer-Tiemann reaction followed by the modified Dakin oxidation. The formyl group introduced by the Reimer-Tlemann reaction had to be converted to the corresponding phenol. After trying many sets of conditions, the Syper process was chosen, which uses arylselenium compounds as activators for the oxidation. Treatment of the aromatic aldehyde with 2.5 equivalents of 30% hydrogen peroxide in the presence of 4% diphenyl diselenide in dichloromethane for 18h gave the aryl formate in excellent yield. This ester was cleaved by treatment with methanolic ammonia for 1h to afford the desired phenol in good yield. 

In the preparation of this new edition advantage has been taken of the opportunity offered to correct a number of errors in the first edition, and to make the text a reproduction of the fourth German edition of Professor Gattermann s book. In many cases the laboratory directions have been improved, a number of new illustrations have been added, and the Special Part now includes methods for the preparation of glycol, di-methylcyclohexenone, s-xylenol, phenylhydroxylamine, nitroso-benzene, p-tolyl aldehyde (Gattermann-Koch synthesis), salicylic aldehyde (Reimer and Tiemann s oxyaldehyde synthesis), cuprous chloride, the decomposition of inactive mandelic acid into its active constituents, and a zinc dust determination. The preparations of acetylene and acetylene tetrabromide have been omitted. 

This reaction is related to the Friedel-Crafts Acylation, Reimer-Tiemann Reaction, Houben-Hoesch Reaction, Gatterman Aldehyde Synthesis, and Vilsmeier-Haack Formylation. 

Nevertheless, compared to other formylation reactions, such as the Duff Formylation, Gattermann Aldehyde Synthesis, and Gattermann-Koch Formylation, the Reimer-Tiemann reaetion is the only one that occurs under basic conditions, and in certain cases, it is the only feasible method for the direct formylation, e.g., the formylation of oestrogens. ... 

A soln. of 6-trichloromethylpurine and phenol in methanolic Na-methoxide refluxed 2 hrs., evaporated to dryness under reduced pressure, dissolved in water, acidified with HGl, and warmed to 50-60° with stirring purin-6-yl 4-hydroxy-phenyl ketone. Y 79%.—This reaction proceeds under milder conditions than the usual Reimer-Tiemann aldehyde synthesis with chloroform. S. Gohen, E. Thom, and A. Bendich, J. Org. Ghem. 28, 1379 (1963). 

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