By C-Formylation

2-Methylpyrazine with dimethylformamide and phosphoryl chloride gave 2-(2 -dimethylamino-l -formylvinyl)pyrazine (717), which was hydrolyzed by alkali to 2-(C,C-diformylmethyl)pyrazine (717). 

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Under controlled conditions, the acetylaminopyrazole 80 was converted by Vilsmeier-Haack reaction to a mixture of chloro derivatives (81 R2 = H, CHO) in poor and moderate yields, respectively. Cyclization is preceded by C-formylation and formation of the imidoyl chloro group.95... 

Pyrazole, C-formyl-conformation, 5, 209 Pyrazole, fluoro-reactions, 5, 263, 267 Pyrazole, 4-fluoro-5-hydroxy-tautomerism, 5, 214 Pyrazole, 1-germyl-synthesis, 5, 236 Pyrazole, halo-halogenation by, 5, 54 reactions, 5, 104, 105, 266 reduction, S, 105, 106, 266 Pyrazole, 3-halo-1-phenyl-quaternary salts... 

In the Meth-Cohn quinoline synthesis, the acetanilide becomes a nucleophile and provides the framework of the quinoline (nitrogen and the 2,3-carbons) and the 4-carbon is derived from the Vilsmeier reagent. The reaction mechanism involves the initial conversion of an acylanilide 1 into an a-iminochloride 11 by the action of POCI3. The a-chloroenamine tautomer 12 is subsequently C-formylated by the Vilsmeier reagent 13 derived from POCI3 and DMF. In examples where acetanilides 1 (r = H) are employed, a second C-formylation of 14 occurs to afford 15 subsequent cyclisation and... 

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). 

These reactions are most important for the preparation of acyl fluorides. " Acyl chlorides and anhydrides can be converted to acyl fluorides by treatment with polyhydrogen fluoride-pyridine solution" or with liquid HF at — 10°C. Formyl fluoride, which is a stable compound, was prepared by the latter procedure from the mixed anhydride of formic and acetic acids. Acyl fluorides can also be obtained by reaction of acyl chlorides with KF in acetic acid or with DAST. Carboxylic esters and anhydrides can be converted to acyl halides other than fluorides by the inorganic acid halides mentioned in 10-77, as well as with PhsPXa (X = Cl or but this is seldom done. Halide exchange can be carried out in a... 

A particularly interesting reaction is the C-formylation[2] of alkylidenephosphoranes by A-formylimidazole to give a-formyl derivatives (C6H5)3P=C(R)CHO which can be further transformed into a,/ -unsaturated aldehydes by Wittig reaction, or hydrolyzed to produce aldehydes RCH2-CHO. 

Streptose is the first branched-chain sugar to have been identified as a component of a biological compound produced by a microorganism. This dicarbonyl sugar is known only in its derivatives. The chemistry of streptose and streptomycin has been lucidly reviewed by Lemieux and Wolfrom.1 In this article, it was noted that streptose must be either 5-deoxy-3-C -formyl-L-ribose or 5-deoxy-3-C-formyl-L-lyxose. Since then, the presence of the latter configuration (XXXIV) has been definitely established by Wolfrom and DeWalt,66 who found that N-acetyltetrahydrostreptobi-... 

Several 9-methyl-1,2,3,4-tetrahydrocarbazoles gave the corresponding I-methyl-3-formylcarbazoles when subjected to Vilsmeier conditions. The process is believed to be initiated by C-1 formylation it was demonstrated that the benzene ring carrying the two new C-1 units was the original tetrahydro ring. ... 

Two 4-methylene-l,3-dioxane diastereoisomers, isomeric at C-6, were subjected to the rhodium-catalyzed hydro-formylation. The stereochemistry of the newly formed stereogenic carbon was guided solely by the acetal stereocenter (not by C-6) (Scheme 56) <1997JA11118, 1998TL6423>. 

The deamination of methyl 3-amino-3-deoxy-/3-D-xylopyranoside (25) gave a mixture which was shown by n.m.r. spectroscopy to contain three components in the ratios of 4 1 1. The major product, methyl 3-deoxy-3-C-formyl-a-L-threofuranoside (26) was characterized as methyl 3-deoxy-3-C-(hydroxymethyl)-a-L-threofuranoside (64%) and its di-p-nitrobenzoate (55%), the structures being established by n.m.r. spectroscopy.115 Methyl 2-deoxy-2-C-formyl-/3-D-threofuranoside (27) was assumed to be a second product, because... 

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