Aldehydes s. a. Formyl

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). 

Oxo-aldehyde konnen nur in Einzelfallen selektiv an der Formyl-Gruppe reduziert werden. Beispiel hierfiir ist die Reduktion von 14/3-Hydroxy-3,19-dioxo-cardadien-(4,2022)-olid mit Penicillium thomii zu 14(i,19-Dihydroxy-3-oxo-cardadien-(4,2022)-olid (55% d.Th.)5 die an sich reaktive 3-Oxo-Gruppe (s.S. 748) ist durch Konjugation mit der C4=Cs-DoppeIbindung desaktiviert (s.a. S.742) ... 

Fischer s aldehydes having a 2-hydroxyethyl or 2-chloroethyl substituent on the N atom and a 5-nitro substituent were prepared by formylation of the corresponding... 

A reaction having significant synthetic importance for the construction of dialkyl 2-formylaIkyl-phosphonates involves the addition of trivalent phosphorus reagents to a,3-unsaturated aldehydes. s This Michael-Michaelis-Arbuzov strategy is the method of choice for incorporating, from readily available Michael-type substrates, one or two substituents at any position of the carbon chain between the phosphoryl and formyl groups. 

Ober die Reduktion von Orthocarbonsaure-Derivaten zu Aldehyden ist wenig bekannt. Zur Umsetzung von Orthoestern mit Lithiumalanat zum Acetal und dessen Hydrolyse zum Aldehyd s. Lit.1 a. Die Transformation einer Trichlormethyl-Gruppe zum Aldehyd ge-lingt in einem speziellen Fall z.B. beim 2-Trichlormethyl-pyrazin mit Natriummethanolat zum 2-Formyl-5-methoxy-pyrazin (40%) b- Allgemein gangbar scheint der Weg jedoch nicht zu sein, da diese Derivate zunachst aus den Carbonsaure-Derivaten hergestellt wer-den. 

Formylamines s. Formamides C-Formylation (s. a. Vilsmeier aldehyde synfliesis)... 

Formylamines s. Formamides C-Formyiation (s. a. C-Hydroxy-methylenation, Aldehyde groups, introduction) 20, 600 —, o-formylation, preferential, of phenols 20, 558 N-Foriiiylation... 

The Gattermann-Koch synthesis of aromatic aldehydes involves a Friedel-Crafts formylation by CICHO in the presence of aluminum chloride and CuCl catalysts. s.n xhe reaction proceeds without Cu, but at much higher pressures. s... 

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