A-formyl

My early work with acyl fluorides also involved formyl fluoride, ITCOF, the only stable acyl halide of formic acid, which was first made in 1933 by Nyesmeyanov, who did not, however, pursue its chemistry. 1 developed its use as a formylating agent and also explored formyla-tion reactions with CO and HF, catalyzed by BF3. 

An example of an intermolecular aldol type condensation, which works only under acidic catalysis is the Knoevenagel condensation of a sterically hindered aldehyde group in a formyl-porphyrin with a malonic ester (J.-H. Fuhrhop, 1976). Self-condensations of the components do not occur, because the ester groups of malonic esters are not electrophilic enough, and because the porphyrin-carboxaldehyde cannot form enolates. 

Conjugated dipyrrolic pigments, the dipyrromethenes, are synthesized by add-catalyzed condensation of an a-formyl pyrrole and an a-unsubstituted pyrrole. They are readily protonated and deprotonated and are difficult to purify by chromatography. 

Similarly, ethyl (or methyl) a-formyl chloroacetate (69), Rj = H, and its substituted derivatives, condensed with thioformamide or higher thioamides give 5-ethyl- or 5-rnethyl-thiazole carboxylates (70) in good... 

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

In the presence of aluminum chloride and a small amount of cuprous haUde, a mixture of hydrogen chloride and carbon monoxide serves as a formyl a ting agent of aromatics (Gattermann-Koch reaction) (107) ... 

The diagrams below give STO-3G calculated charge densities for the betu l cation and its a-formyl and a-cyano derivatives. Analyze die effect of these substituents on... 

For the purpose of our discussion, a polycrown is here defined as a polymer system arising by polymerization of a crown monomer unit. Extensive work has been done in this field by Kopolow, Hogen Esch and Smid and the examples presented here are taken from a paper by all three of these workers. A typical preparation of vinylbenzo-15-crown-5 is accomplished according to the scheme shown as Eq. (6.25). One might also have utilized a formylation/Wittig sequence on benzo-15-crown-5 to accomplish the same end. 

HCO2H, DCC, Pyr, 0°, 4 h, 87-90% yield." These conditions produce A-formyl derivatives of f-butyl amino acid esters with a minimum of racemization. 

A recent report describes the conversion of A-formyl- and N-acetyl-L-leucine into optically active azlactones with dicyclohexyl-carbodiimide (DCC) [Eq. (29)]. Other cyclization reagents, e.g. acetic anhydride, POCI3, SOCI2, and polyphosphoric acid, cause racemiza-tion. These azlactones react with optically active amino acid esters to give esters of dipeptides with retention of activity. 

The anion of A-nitromethyIphthalimide 17 also acts as a formyl anion equivalent with Michael acceptors to afford 1,4-dicarbonyl compounds 18 in good to excellent yields, although difficulty was experienced in isolating the products under the conditions required for removal of the phthalimide group (77CJC2919). 

The triazole 76, which is more accurately portrayed as the nucleophilic carbene structure 76a, acts as a formyl anion equivalent by reaction with alkyl halides and subsequent reductive cleavage to give aldehydes as shown (75TL1889). The benzoin reaction may be considered as resulting in the net addition of a benzoyl anion to a benzaldehyde, and the chiral triazolium salt 77 has been reported to be an efficient asymmetric catalyst for this, giving the products (/ )-ArCH(OH)COAr, in up to 86% e.e. (96HCA1217). In the closely related intramolecular Stetter reaction e.e.s of up to 74% were obtained (96HCA1899). 

Pyridinium p-toluenesulfonylmethylide 91 has been used as a formyl anion equivalent for conjugate addition to N-substituted maleimides to give the enol ethers 92, which were readily deprotected to give the aldehydes 93 (80TL705). 

The preparation of a formyl-substituted aromatic derivative 3 from an aromatic substrate 1 by reaction with hydrogen cyanide and gaseous hydrogen chloride in the presence of a catalyst is called the Gattermann synthesis This reaction can be viewed as a special variant of the Friedel-Crafts acylation reaction. 

The Michael acldiQon of rutromethane to cyclopentenone clenvaQves is used for synthesis of prostaglandins fScheme 4 20 Here, the aruon of rutromethane is used as a formyl aruon synthon... 

The mtrodncdon of a formyl or acyl group can be achieved by transformadon of VNS products. Hydrolysis ofthchloromethylnitroarenes, VNS products betweenheteroaromadcnitro compoimds and chloroform, is amethodof choice for the preparadon of heterocyclic Mdehydes, as shown in Eq. 9.41, in which 4-nitroimida2oleis converted into 5-formyl-4-nitroimidazole. ... 

In the Gatteinicin-Koch reaction, a formyl group (-CHO) is introduced directly onto a benzene ring. For example, reaction of toluene wjfh CO and HCJ in the presence of mixed CUCI/AICI3 gives p-methylbenzaldehyde. Propose a mechanism. 

When it s necessary to refer to the R-C=0 as a substituent, the name acyl (a-sil) group is used and the name ending -yl is attached. Thus, CFI3CO is an acetyl group, CHO is a formyl group, and C6H5CO is a benzoyl group. 

S)-A -Formyl-.Y-(2,.3,4-tri-D-pivaloyl-z-n-arabinopyranosylWert-leucine ferf-Butylamide Typical Procedure76 7S ... 

The reaction proceeds via die hydrolysis of nitrile groups to an amide. The amides may also be A-formyl amines, which react with acid groups whereby volatile formic acid is shipped10 ... 

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