PRANLUKAST

PRANLUKAST

Antiasthmatic.

Launched – 1995 japan150821-03-7, C27 H23 N5 O4 . H2O, 499.5179

103177-37-3 anhydrous, 103180-28-5 (monosodium salt)

Ono-1078
Ono-RS-411
RS-411
SB-205312
Ono-1070 (monosodium salt)

N-[4-Oxo-2-(1H-tetrazol-5-yl)-4H-1-benzopyran-8-yl]-4-(4-phenylbutoxy)benzamide hemihydrate

Ono (Originator)Schering-Plough (Licensee)

……….

J Med Chem 1988, 31(1): 84,

WO 2010002075,

Synth Commun 1997, 27(6): 1065,

WO 1994012492

Leukotriene antagonist.

Prepn: M. Toda et al., EP 173516; eidem, US 4780469 (1986, 1988 both to Ono);

H. Nakai et al., J. Med. Chem. 31, 84 (1988).

Pharmacology: T. Obata et al., Adv. Prostaglandin Thromboxane Leukotriene Res. 15, 229 (1985); idem et al., ibid. 17,540 (1987).

Clinical evaluations in asthma: Y. Taniguchi et al., J. Allergy Clin. Immunol. 92, 507 (1993); H. Yamamoto et al. Am. J. Respir. Crit. Care Med. 150, 254 (1994).

AU 8546462; EP 0173516; JP 8650977; US 4780469; US 4939141

Pranlukast is a cysteinyl leukotriene receptor-1 antagonist. It antagonizes or reduces bronchospasm caused, principally in asthmatics, by an allergic reaction to accidentally or inadvertently encountered allergens.

Pranlukast is a cysteinyl leukotriene receptor-1 antagonist. This drug works similarly to Merck & Co.‘s Singulair (montelukast). It is widely used in Japan.

Medications of this class, which go under a variety of names according to whether one looks at the American, British or European system of nomenclature, have as their primary function the antagonism of bronchospasm caused, principally in asthmatics, by an allergic reaction to accidentally or inadvertently encountered allergens.

Medications of this group are normally used as an adjunct to the standard therapy of inhaled steroids with inhaled long- and/or short-acting beta-agonists. There are several similar medications in the group; all appear to be equally effective.

1. Nakade S, Ueda S, Ohno T, Nakayama K, Miyata Y, Yukawa E, Higuchi S (2006). “Population pharmacokinetics of pranlukast hydrate dry syrup in children with allergic rhinitis and bronchial asthma.”. Drug Metab Pharmacokinet 21 (2): 133–9. doi:10.2133/dmpk.21.133. PMID 16702733.

Toda synthetic complete with 3 – nitro-2 – hydroxyphenyl ko one for raw materials, ni ko with oxalic ester Claisen condensation occurs, and then heated to reflux for cyclization to construct benzo pyran ring; dehydrated by an amide synthesized ring cyano group, the cyano compound and then with sodium azide tetrazole synthesis. The nitro group on the compound in 5% Pd / C catalyzed hydrogenation of amino acid reacted with the compound Pranlukast held. This method directly using 4 – (4 – phenyl-butoxy)-benzoic acid reaction. Synthetic route is as follows:

[0006]

[0007]

[0008] ② Robert Graham and routes are routes to I-bromo-butane as a raw material, were used as a palladium catalyst, ligand compound formylation carbonylation reactions and condensation of potassium tert-butoxide, closed dehydration under acidic conditions benzopyran ring method. Synthetic route is as follows:

[0009] Robert routes:

[0010]

[0011] Graham route:

[0012]

[0013] The two synthetic routes are not disclosed in the I-Bromo butane feedstock pathway.

[0014] ③ Masayohi 2_ cyano synthetic route to a benzopyran derivative and hydrogen sulfide gas in the base-catalyzed addition reaction of 2 – thiocarbamoylbenzothiazol and pyran derivatives, and then were reacted with anhydrous hydrazine group hydrazone, with sodium nitrite under acidic conditions nitrosation reaction occurs tetrazole ring. Synthetic route is as follows:

[0015]

[0016] The materials used are not mentioned route synthesis method, it is only reflected in the improvement of the synthesis of the tetrazole ring.

[0017] ④ Giles, Hideki and Hayler are tetrazole substituent on the increase, making it easier condensation reaction, but the synthesis of substituted on the nitrogen with tetrazole difficult, and ultimately elimination reaction of lithium used tetrahydro aluminum and other hazardous reagents, is not easy to Eri industrialization. Reaction scheme is as follows:

[0018]

[0019] ⑤ Lee NK with 4_ (4_ Phenylbutoxy) benzonitrile and 2_ hydroxy _3_ iodobenzene ko 1H_4_ thiazolyl ketone and ester ko _5_ acid, concentrated sulfuric acid catalyzed cyclization iodide copper and potassium phosphate removal under the action of hydrogen iodide get Pranlukast held. Reaction scheme is as follows:

[0021] does not mention the route starting 4 – (4 – phenyl-butoxy)-benzonitrile synthesis method, while two – hydroxy – 3 – Synthesis of iodobenzene ko difficult one.

The synthesis method comprises the following steps: a. 4 – Synthesis of chlorobutanol THF was added concentrated hydrochloric acid, feeding the mass ratio of I: I. 389 ~ 5. 556,45-80 ° C was stirred for 5-18h, cooled, extracted with methylene chloride, removal of the solvent, distillation under reduced pressure to give 4 – chlorobutanol; b. 4 – phenyl butanol take benzene, aluminum chloride mixture ,0-25 ° C solution of 4 – chlorobutanol, reaction 5 -10h then poured into ice-water, a liquid, in addition to homogeneous solution U, distillation under reduced pressure, and the resulting colorless transparent liquid that is, 4 – phenyl butanol; c. I-bromo-4 – phenyl butane synthesis of 4 – phenyl butanol 40% hydrobromic acid mixture, feeding the mass ratio of I: 2. 857 ~ 11. 428, heat refluxing, cooling, liquid separation, the organic solvent divided by distillation under reduced pressure to give I-bromo-4 – phenyl butane; d. Synthesis of methyl p-hydroxybenzoate take-hydroxybenzoic acid and methanol, concentrated sulfuric acid and refluxed for 5-20h spin methanol, poured into cold water to precipitate a white solid which was filtered and dried to give the hydroxy benzoate; e. 4 – (4 – phenyl-butoxy)-benzoic acid methyl ester _ take I-bromo-4 – phenyl butane, DMF, toluene, methyl p-hydroxybenzoate and potassium carbonate, a reflux 5 ~ 20h, cooling water, extracted with toluene, light yellow liquid rotary evaporation, recrystallization, and the resulting white solid, that is, 4 – (4 – phenyl-butoxy) – benzoic acid methyl ester; f. 4 – (4 – phenyl-butoxy yl) – benzoic acid taken 4 – (4 – phenyl-butoxy) – benzoic acid methyl ester, 15% NaOH solution was refluxed for I ~ 5h, cooled, acidified, filtered and dried to give 4 – (4 – phenylbutyrate oxy) – benzoic acid; g. sprinkle bromophenyl acetic acid ester molar ratio Preparation of I: I ~ I. 5: O. I ~ I of bromophenol, acetic anhydride, pyridine feeding, reflux 3 ~ 10h, distilled pyridine, acetic acid and excess acetic anhydride distilled under reduced pressure to give the acetic acid esters bromophenol; h. 5 – bromo-2 – Preparation of light taken acetophenone molar ratio of I: I ~ 5: I of acetic acid bromophenol esters, aluminum chloride, tetrachlorethylene for feeding, reflux O. 5 ~ 5. 5h, cooled, the reaction solution was poured into 5% hydrochloric acid and extracted with methylene chloride, the solvent evaporated under reduced pressure, to obtain a gray crystalline 5 – bromo-2 – Light acetophenone; i. 5 – bromo-3 – nitro-2 – Preparation of light acetophenone take 5 – bromo-2 – Light acetophenone, carbon tetrachloride, 50 ~ 90 ° C is added dropwise nitric acid, reflux I ~ 4h, cooled, filtered, and the resulting yellow solid which is 5 – bromo-3 – nitro-2 – hydroxyacetophenone; j. 3 – amino-2 – Light benzene ethanone Preparation of 5 – bromo-3 – nitro-2 – hydroxyacetophenone, 5% Pd / C, methylene chloride, methanol, concentrated hydrochloric acid, water, hydrogenation; the end of the reaction mixture was filtered, the filtrate was The solvent was removed, neutralized with sodium bicarbonate, and the resulting yellow solid ginger i.e., 3 – amino-2 – hydroxyacetophenone; k. 3 – [4 - (4 - phenyl-butoxy)-benzoyl amino] -2 _ light base Preparation of acetophenone 4 – (4 – phenyl-butoxy)-benzoic acid, toluene, DMF, 45 ~ 105 ° C was added dropwise SOCl2, 30min the reaction liquid droplets to the 3 – amino-2 – hydroxyphenyl toluene solution of ethyl ketone, the reaction 3 ~ 10h, cooled, neutralized with dilute hydrochloric acid, extracted with toluene, rotary evaporation, and the resulting pale yellow crystals is 3 – [4 - (4_ phenylbutoxy) benzamido] 2_-hydroxyacetophenone; I. 2 – [4 - (4 - phenyl-butoxy)-benzoyl amino] -6 – [l, 3 - dioxo-3 - ethoxycarbonyl-propyl] phenol synthetic sodium, THF, 3 – [4 - (4 - phenyl-butoxy)-benzoyl amino]-2 – hydroxyacetophenone, diethyl oxalate 4 ~ IOh After stirring the reaction was poured into dilute hydrochloric acid to precipitate the yellow solid which was filtered, and the resulting product, i.e. 2 – [4 - (4_ phenylbutoxy) benzamido] _6_ [1,3 - dioxo-3 - ethoxy propyl intended yl] phenyl discretion ·; m. 4 – oxo-8 – [4 - (4 - phenyl-butoxy)-benzoyl amino]-2 – ethoxycarbonyl-4H-benzopyran take 2 – [4 - (4 - phenyl-butoxy yl) benzoyl amino] -6 – [l, 3 - dioxo-3 - ethoxycarbonyl-propyl] phenol, THF, force mouth heat, the addition of concentrated hydrochloric acid, refluxed for 8 ~ 15h, cooled, filtered, and the resulting white solid, that is, 4 – oxo-8 – [4 - (4 - phenyl-butoxy)-benzoyl amino]-2 – ethoxycarbonyl-4H-benzopyran; η. 4 – oxo-8 – [ 4 - (4 - phenyl-butoxy)-benzoyl amino] -2 – amino-carbonyl-4Η-benzopyran synthesis take four – oxo-8 – [4 - (4 - phenyl-butoxy)-benzoyl amino] -2 – ethoxycarbonyl-4Η-benzopyran was dissolved in DMF, and leads to dry ammonia gas, the reaction solution changed from yellow to red, the reaction solution was poured into cold water, adjusted to acidic, and filtered to give the product 4 – oxo-8 – [4 - (4 - phenyl-butoxy)-benzoyl amino] -2 – amino-carbonyl-4Η-benzopyran; P. 4 – oxo-8 – [4 - (4 - phenylbutoxy) benzamido] -2 – cyano-4Η-benzopyran take DMF, S0C12, 4 – oxo-8 – [4 - (4 - phenyl-butoxy)-benzoic amido] _2_ aminocarbonyl-4H-benzopyran, O ~ 15 ° C under stirring for 2 ~ IOh poured into cold water, filtered, and the resulting white solid that is, 4 – oxo-8 – [4 - (4 - phenylbutoxy) benzamido] -2 – cyano-4H-benzopyran; q. Synthesis of pranlukast take four – oxo-8 – [4 - (4 - phenyl-butoxy) benzoyl amino]-2_ cyano-4H-benzopyran, ammonium chloride, sodium azide, DMF, heating I ~ 8h then poured into ice-water, dilute hydrochloric acid, filtered, and the resulting white solid that the final product Pranlukast.

The reaction of ethyl 8-nitro-4-oxo-1-benzopyran-2-carboxylate (I) with ammonia in methanol gives the corresponding amide (II), which is dehydrated with POCl3 yielding 2-cyano-8-nitro-1-benzopyran-4-one (III). The cyclization of (III) with sodium azide by means of pyridinium chloride in hot DMF affords 8-nitro-2-(tetrazol-5-yl)-1-benzopyran-4-one (IV), which is hydrogenated with H2 over Pd/C in methanol – HCl giving 8-amino-2-(tetrazol-5-yl)-1-benzopyran-4-one (V). Finally, this compound is condensed with 4-(4-phenylbutoxy)benzoic acid (VI) by means of oxalyl chloride in dichloromethane-pyridine