Groups formyl

Since (A) does not contain any other functional group in addition to the formyl group, one may predict that suitable reaction conditions could be found for all conversions into (A). Many other alternative target molecules can, of course, be formulated. The reduction of (H), for example, may require introduction of a protecting group, e.g. acetal formation. The industrial synthesis of (A) is based upon the oxidation of (E) since 3-methylbutanol (isoamyl alcohol) is a cheap distillation product from alcoholic fermentation ( fusel oils ). The second step of our simple antithetic analysis — systematic disconnection — will now be exemplified with all target molecules of the scheme above. For the sake of brevity we shall omit the syn-thons and indicate only the reagents and reaction conditions. 

A mild procedure which does not involve strong adds, has to be used in the synthesis of pure isomers of unsymmetrically substituted porphyrins from dipyrromethanes. The best procedure having been applied, e.g. in unequivocal syntheses of uroporphyrins II, III, and IV (see p. 251f.), is the condensation of 5,5 -diformyldipyrromethanes with 5,5 -unsubstituted dipyrromethanes in a very dilute solution of hydriodic add in acetic acid (A.H. Jackson, 1973). The electron-withdrawing formyl groups disfavor protonation of the pyrrole and therefore isomerization. The porphodimethene that is formed during short reaction times isomerizes only very slowly, since the pyrrole units are part of a dipyrromethene chromophore (see below). Furthermore, it can be oxidized immediately after its synthesis to give stable porphyrins. 

Stigmasterol from soy bean extracts can be selectively ozonolyzed on the side-chain double bond. The 20-formyl group formed is converted to the enamine with piperidine. This can be oxidized to progesterone. 

When a formyl group (—CH=0) is attached to a nng the ring name is followed by the suffix carbaldehyde... 

Modifications iaclude the use of P-ketoaldehydes as acetals, eg (9), which leads to loss of the formyl group (21) the product ia this example is 5-ethoxycarbonyl-2-methylpyrrole [3284-51 -3]. 

Oxo or Hydroformylation and Hydroesterification. Reactions of alkenes with hydrogen and formyl groups are cataly2ed by HCo(CO)4... 

Fig. 2. Enzyme catalysis by glycinaminde nbonucleotide transfomiylase (GAR TFase). (a) Transfer of the formyl group from (13) to (12) to form 2-(formylamino)-A/-(5-0-phosphono-P-D-ribofuranosyl acetamide [349-34-8] (14) and (b) multisubstrate inhibitor (15).

Appropriate pyrido[2,3-d]pyrimidin-5-ones with formyl groups in the 6-position have been oxiized to piromidic (68) and pipemidic (69) acids, or to intermediates for these, using moist silver oxide, chromium trioxide (potassium dichromate), potassium permanganate or, alternatively, sodium chlorite/hydroxylamine-O-sulfonic acid. 6-Acetyl groups have been similarly oxidized using sodium hypobromite in aqueous dioxane, whilst 2-acetyl groups give dimethylaminomethylene derivatives en route to 2-pyrazolylpyrido[2,3-d]pyrimidines. 

A 4-nitro-l, 2-methylenedioxybenzene has been cleaved to a catechol with 2 N NaOH, 90°, 30 min a similar compound substituted with a 4-nitro or 4-formyl group has been cleaved by NaOCH3/DMSO, 150°, 2.5 min (13-74% catechol, 6-60% recovered starting material). ... 

The formyl group was lost during attempted protection with ethylene glycol, TsOH. 

The formyl group is cleaved with HF/anisole/(CH2SH)2- It is also cleaved at pH 9-10. ... 

An example of a 7t-acceptor group is the formyl group as in acrolein. 

Notice that the MO picture gives the same qualitative picture of the substituent effects as described by resonance structures. The amino group is pictured by resonance as an electron donor which causes a buildup of electron density at the /3 carbon, whereas the formyl group is an electron acceptor which diminishes electron density at the /3 carbon. 

Adjacent formyl groups facilitate the hydrolysis of certain aromatic esters, as illustrated by the examples below. Indicate a mechanism for this rate enhancement. ... 

A fluorine-hydrogen migration is typical for the reactions of aldehydes branched at the carbon atom a to the formyl group. Comparable amounts of 1,1 -difluoroalkanes and 1,2-difluoroalkanes together with bis(l -fluoroalkyl) ethers are obtained [169] (equation 84). 

Because aldehydes react with aminofluorosulfuranes more readily than ketones, keto aldehydes can be selectively fluorinated at the formyl group [94, 183] Haloacetaldehydes react with DAST to give bis(l-fluorohaloethyl) ethers as the only or main products [170] (equation 96)... 

The reaction ot tormamides with sulfur tetrafluoride in the presence of potassium fluoride leads to replacement of both carbonyl oxygen and hydrogen with fluorine. The formyl group is directly converted into the trifluoromethyl group A-(trifluoromethyl)amines are formed in near quantitative yields [233] (equation 121)... 

Formylpyrrole oxidatively adds to [Os3(CO)lo(AN)2] by its formyl group giving rise to product 59 followed by cleavage of the C—H bond of this moiety [86JOM(311)371 90OM6]. The complex 59 easily decomposes to 47 and 48. Species 59 further reacts with triethylamine to yield 60 (97P3775). 

The 3-formyl group of 8-substituted 3-formyl-2-hydroxy-4//-pyrido[l,2-n]pyrimidin-4-one was reacted with (cyanomethyl)- and (terr-butoxycarbo-nylmethylene)triphenylphosphorane in THF, and with 5-aminotetrazole in boiling MeOH for 9h to yield ( )-3-propenenitrile, terr-butyl ( )-3-propenoate and 3-[(2//-tetrazol-5-yl)imino]methyl derivatives, respectively (OlMIPl). 

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