Hydroxychloroquinoline

We repeated this work and we found that the o- and p-chloro derivatives were cyclized with equal ease under the conditions used previously (3) for the m-chloro derivative, giving almost quantitative conversion of the acrylates to 4-hydroxychloroquinoline-3-carboxylic acids.

Chloroquine is available as the phosphate (Avlochlor), and as the sulphate (Nivaquine). The drug is usually given orally, but may be given by slow intramuscular or intravenous injection for the emergency treatment of the acute attack. Hydroxychloroquinoline (Plaquenil) has similar properties.

[Use of hydroxychloroquinoline in the treatment of diarrheas of varied etiology] Bernades P. / Sem Hop Paris 41:1699-702, 8 Jun 65 (Fr)

The introduction of the chlorine atom in 4-position, so as to obtain the desired dichloroquinolines of the above formula was most commonly effected by reacting phosphorus oxychloride with the corresponding 4-hydroxychloroquinoline, that is, a molecule having already a tertiary endocyclic nitrogen (see for example for these processes: J.A.C.S. 68 (1946) p. 113, 1204; J.A.C.S. 71 (1949) p. 1901; J.A.C.S. 73 (1951) p. 3168; J.A.C.S. 74 (1952) p. 5889; Chem. Ber. (1958) p. 499, etc.).

Hydroxychloroquinoline, affecting platelets, 292

One of these is an ester group whose saponification gives an acid, which is decarboxylated to give a hydroxychloroquinoline (5).

The heterocyclic part of HCQ, 1, is rather inexpensive (1.50 $ per g from S-A, 0.26 $ per g from Biosynth Carbosynth) and in case of supply problems, can be sourced (in 94% yield, via chlorination using POCl₃) from hydroxychloroquinoline 13 which, in turn, can be made in ~40% yields in two steps either from 3-chloroaniline, diethyl malonate and ethyl orthoformate (respectively, 9.51 $ per g from S-A, 0.05 $ per g from Oakwood Chemical, OC; 0.04 $ per g from S-A, 0.015 $ per g from OC; 0.12 $ per g from S-A, 0.03 $ per g from OC) or from 3-chloroaniline, acrylic acid (or methyl acrylate) and tosyl chloride (respectively, 9.51 $ per g from S-A, 0.05 $ per g from OC; 1.48 $ per g from S-A, 0.02 $ per g from Gelest Inc.; 1.43 $ per g from S-A, 0.03 $ per g from Alfa Aesar; 0.02 $ per g from S-A, 0.04 $ per g from Alfa Aesar).