Quelet reaction

Blanco Directo process Blanc-Quelet reaction Blanket crepes Bla-S... 

QUELET REACTION. Passage of dry hydrogen chloride through a solution in inligroin of a phenolic ether and an aliphatic aldehyde in the presence or absence of a dehydration catalyst to yield (y-chloroalkyl derivatives by substitution in the para position to the ether group or in the ortho position in pom-substituted phenolic ethers. 

Other references related to the Quelet reaction are cited in the literature. ... 

In 1932, Quelet used the Blanc procedure, replacing formaldehyde with aliphatic aldehydes in the reaction with phenolic ethers. The resulting reaction mixtures were found to contain a-chloroalkyl derivatives. Although the conditions are virtually identical and the reaction proceeds via the same basic mechanism, the Blanc chloromethylation is often referred to as the Quelet reaction. 

Hara and co-workers used the Blanc reaction for the synthesis of a key intermediate toward a series of benzodiazepines. Since their goal was ultimately the installation of an ethyl substituent at C-4, in lieu of a formaldehyde precursor like trioxane or paraformaldehyde, acetaldehyde was used, in a manner similar to the Quelet reaction. As commonly observed under these conditions, alkene 30 was isolated along with product 29. Given that the alkene 30 was also a desired product, the reaction mixture was simply heated with pyridine, resulting in complete conversion to 30. To complete the installation of the ethyl substituent, the alkene of 30 was subsequently reduced. 

In a similar marmer, work done by Quelet also focused on the chloromethylation reaction of substituted aromatic rings such as p-methylanisole. Mallory and co-workers used this reaction as a key step in their synthesis of 2-methylphenanthrene (21). In the initial stages of synthesis, / -methylanisole (18) was converted to 2-(chloromethyl)-4-methylanisole (19). Subsequent ylide formation and Wittig reaction with benzaldehyde to give 20 was followed by a photocyclization to produce 21. A similar chloromethylation reaction has been used in efforts toward the synthesis of macrocyclic ligands. ... 

Preparation by [Quelet (bromomethylation) reaction] of 5-chloro-2-hydroxyac-etophenone [2482] according to [2483], m.p. 74-76° [2482]. 

Studies of the chloromethylation of benzene b " reaction with paraformaldehyde and h drogen chloride in the presence of zinc chloride are also reported Ijy Sabetay and Quelet. In 1931, Vorozhtzo " and Yumigina carried out reactions with aqueous fomialdeh de and obtained a 46 per cent yield of benzyl chloride plus a small amount of xylylene dichlorides by heating a saturated solution of hydi ogen chloride in 36 per cent formaldehyde for 6 houns at 60 °C with equal w eights of benzene and zinc chloride. 

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