合成路线1

The Friedel-Crafts' condensation of 1,3-difluorobenzene (I) with chloroacetyl chloride (II) by means of AlCl3 yields alpha-chloro-2,4-difluoroacetophenone (III), which is treated with 1,2,4-triazole (IV) and triethylamine in refluxing ethyl acetate giving alpha-(1H-12,4-triazol-1-yl)-2,4-diftuoroacetophenone (V). The reaction of (V) with trimethylsulfoxonium iodide (VI) by means of NaOH in toluene affords 1-[2-(2,4-di fluorophenyl)-2,3-epoxypropyl]-1H-1,2,4-triazole (VII), which is finally treated again with 1,2,4-triazole (IV) and K2CO3 in hot DMF.

合成路线2

The Friedel-Crafts condensation of 1,3-difluorobenzene (I) with 1-acetylpiperidine-4-carbonyl chloride (II) by means of AlCl3 in dichloromethane gives 1-acetyl-4-(2,4-difluorobenzoyl)piperidine (III), which is hydrotyzed with refluxing 6N HCl to yield 4-(2,4-difluorobenzoyl)piperidine (IV). The reaction of (IV) with hydroxylamine in refluxing ethanol affords the corresponding oxime (V), which is cyclized by means of KOH in boiling water giving 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole (VI). Finally, this compound is condensed with 3-(2-chloroethyl)-2-methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidin-4-one (VII) by means of K2CO3 and Kl in a variety of solvents.

合成路线3

The condensation of tetrahydropyran-4-carbonyl chloride (V) with refluxing 1,3-difluorobenzene (VI) by means of AlCl3 gives 1-(2,4-difluorophenyl)-1-(tetrahydropyran-4-yl)methanone (VII), which is treated with hydroxylamine hydrochloride and sodium acetate in refluxing ethanol/water to yield the corresponding oxime (VIII). The cyclization of (VIII) by means of KOH in refluxing methanol affords 6-fluoro-3-(tetrahydropyran-4-yl)-1,2-benzisoxazole (IX), which is treated with NaI and Ac-Cl and then with K2CO3 in refluxing acetonitrile to provide the 5-iodopentanol derivative (X). The reaction of the OH group of (X) with Ms-Cl and TEA in dichloromethane gives the corresponding mesylate (XI), which is finally cyclized with the intermediate amine (IV) by means of NaHCO3 in refluxing acetonitrile to yield the target piperidine.

合成路线4

The condensation of piperidine-4-carboxylic acid (VI) with ethyl chloroformate (VII) by means of Na2CO3 in toluene/water gives 1-(ethoxycarbonyl)piperidine-4-carboxylic acid (VIII), which is treated with SOCl2 to yield the corresponding acyl chloride (IX). The Friedel-Crafts condensation of (IX) with refluxing 1,3-difluorobenzene (X) by means of AlCl3 gives 4-(2,4-difluorobenzoyl)piperidine-1-carboxylic acid ethyl ester (XI), which is treated with concentrated HCl at 100 C to yield 4-(2,4-difluorobenzoyl)piperidine (XII). The condensation of piperidine (XII) with the 2-chloroethyl intermediate (V) by means of KI and NaHCO3 in refluxing acetonitrile affords the adduct (XIII), which is treated with hydroxylamine hydrochloride and KOH in refluxing pyridine/ethanol to provide the corresponding oxime (XIV). Finally, this compound is cyclized by means of KOH in refluxing water or with NaH in refluxing THF to afford in both cases the target 1,2-benzisoxazole.

合成路线5

A synthesis of Sch-42427, the active (RR)-enantiomer of Sch-39304, has been published: The condensation of 1,3-difluorobenzene (I) with (S)-2-chloropropionyl chloride (II) by means of AlCl3 gives 2(S)-chloro-1-(2,4-difluorophenyl)-1-propanone (III), which is reduced with NaCNBH3 to the corresponding alcohol (IV). Epoxidation of (IV) with K2CO3 in methanol yields the chiral epoxide (V). The oxidative opening of (V) by means of BF3 in DMSO affords (R)-1-(2,4-difluorophenyl)-2-hydroxypropanone (VI), which is protected with dihydropyran (DHP) and p-toluenesulfonic acid to the tetrahydropyranyl ether (VIII). Alternatively, the treatment of (V) with trimethylsilyl bromide and dihydropyran gives the (R)-bromo-tetrahydropyranyl ether (VII), which can be oxidized to (VIII) with silver benzoate. The reaction of (VIII) with sodium dimethylsulfoxonium methylide in THF gives the epoxide (IX), which is opened with sodium 1,2,4-triazole (X) to yield the semi-protected diol (XI). Hydrolysis of (XI) in acidic medium affords the diol (XII), which is treated with methanesulfonyl chloride and triethylamine to afford the mono methanesulfonyl ester (XIII). The reaction of (XIII) with sodium methyl mercaptane gives the thioether (XIV), which is finally oxidized with peracetic acid.

合成路线6

A new synthesis of the active (R,R)-isomer of SM-8668 has been reported: The Friedel-Crafts condensation of 1,3-difluorobenzene (I) with 2-bromopropionyl bromide (II) by means of AlCl3 gives the corresponding propiophenone (III), which is treated with sodium methylmercaptide to yield 2',4'-difluoro-2-(methylsulfanyl)propiophenone (IV). The reaction of (IV) with trimethylsulfoxonium chloride affords the epoxide (V) as a D,L-threo-mixture of isomers, which is treated with a chiral carboxylic acid (VI), giving the diastereomeric mixture of esters (VII). The separation of the isomers by column chromatography or fractional crystallization affords the (2R,3R)-isomer (VIII), which by hydrolysis with NaOH is converted to the diol (IX). The epoxidation of the diol (IX) with mesyl chloride, NaOH and benzyltriethylammonium chloride yields the (2R,3R)-epoxide (X), which is condensed with 1,2,4-triazole (XI) by means of NaOH to give the precursor (XII). Finally, this compound is oxidized with H2O2 and sodium tungstate.

合成路线7

The synthesis of [9-14C]-SM-10888 has been described: The carboxylation of 1,3-difluorobenzene (I) with labeled CO2 by means of butyllithium in THF gives 2,6-difluorobenzoic acid (II), which by reaction first with SOCl2 and then with NH4OH yields the corresponding amide (III). The reaction of (III) with SOCl2 in hot DMF affords the nitrile (IV), which by reaction with ammonia in ethanol at 135 C gives 2-amino-6-fluorobenzonitrile (VI). Finally, this compound is cyclized with bicyclo[3.3.1]heptan-2-one (VI) by means of ZnCl2 at 105 C in nitrobenzene.

合成路线8

The reaction of piperidine-4-carboxylic acid (I) with formic acid and acetic anhydride gives 1-formylpiperidine-4-carboxylic acid (II), which is treated with SOCl2 and acetic anhydride to yield the corresponding acyl chloride (III). The Friedel-Crafts condensation of (III) with refluxing 1,3-difluorobenzene (IV) by means of AlCl3 affords 4-(2,4-difluorobenzoyl)-1-formylpiperidine (V), which is treated with hydroxylamine in refluxing ethanol to give the corresponding oxime (VI). The cyclization of (VI) by means of NaH in hot THF/DMF yields 6-fluoro-3-(1-formylpiperidin-4-yl)-1,2-benzisoxazole (VII), which is treated with HCl in refluxing ethanol to afford 6-fluoro-3-(4-piperidyl)-1,2-benzisoxazole (VIII). Finally, this compound is condensed with 4-(3-chloropropoxy)-3-methoxyacetophenone (IX) by means of K2CO3 in hot DMF. The intermediate 4-(3-chloropropoxy)-3-methoxyacetophenone (IX) can be obtained by condensation of 4-hydroxy-3-methoxyacetophenone (IX) with 3-chcloropropyl bromide (X) by means of NaH or K2CO3 in DMF.

合成路线9

The Friedel Craft condensation of 1,3-difluorobenzene (I) with succinic anhydride (II) gives the 4-oxobutyric acid (III); which by a Wittig reaction with methylene triphenylphosphorane (IV) yields the 4-pentenoic acid (V). The condensation of (V) with the chiral auxiliary, 4(R)-benyzloxazolidin-2-one (VI) by means of pivaloyl chloride and BuLi affords the chiral imide (VII), which is submitted to a diastereoselective hydroxymethylation with trioxane and TiCl4 in THF to provide the hydroxymethyl adduct (VIII). The direct iodocyclization of (VIII) by means of I2 and pyridine in acetonitrile gives the chiral cis-tetrahydrofuran derivative (IX). The reductive cleavage of the chiral auxiliary of (IX) by means of LiBH4 in THF yields the iodoalcohol (X)???(X)a, which is condensed with 1,2,4-triazole sodium salt (XI) to afford the adduct (XII). Finally, this compound is treated with Ts-Cl and pyridine to afford the target intermediate tosylate (XIII) (see scheme no. 20027601a, intermediate no. (II)).

合成路线10

Treatment of 4-nitrophenol (I) with propyl iodide derivative (II) and K2CO3 in DMF, followed by reduction with hydrazine hydrate, FeCl3 and activated carbon affords (III). Conversion of aniline derivative (III) into phenylcarbamate (IV) by means of PhOCOCl and treatment of (IV) with hydrazine hydrate yields semicarbazide (V), which is then subjected to cyclization with formamidine (VI) to give triazolone derivative (VII). Benzyl (S)-lactate (VIII) is converted to triflate (IX) by means of Tf2O in the presence of DIEA and its reaction with triazolone (VII) and NaH in DMF provides derivative (X). Debenzylation of (X) by hydrogenolysis over Pd/C followed by treatment with oxalyl chloride in CH2Cl2/DMF furnishes chloride (XI), which reacts with 1,3-difluorobenzene (XII) in CH2Cl2 in the presence of AlCl3 to yield intermediate (XIII).

合成路线11

3) The Friedel Crafts condensation of m-difluorobenzene (XXXIV) with succinic anhydride (XXXV) gives 4-(2,4-difluorophenyl)-4-oxobutyric acid (XXXVI), which is converted by a Wittig reaction into 4-(2,4-difluorophenyl)-4-pentenoic acid (XXXVII) and subsequently into its acyl chloride (XXXVIII). The condensation of (XXXVIII) with 4(R)-benzyloxazolidin-2-one (XXXIX) gives the acyl oxazolidinone (XL), which is regioselectively hydroxymethylated with 1,3,5-trioxane and TiCl4 to afford 4(R)-benzyl-3-[4-(2,4-difluorophenyl)-3(S)-(hydroxymethyl)-4-pentenoyl] oxazolidin-2-one (XLI). The cyclization of (XLI) with iodine and pyridine yields the tetrahydrofuran derivative (XLII), which is reduced with LiBH4 to (5R-cis)-5-(2,4-difluoromethyl)-5-(iodomethyl)tetrahydrofuran-3-methanol (XLIII). Finally, this compound is condensed with sodium 1,2,4-triazole (XXXI) to afford (5R-cis)-5-(2,4-difluoromethyl)-5-(1,2,4-triazol-1-ylmethyl) tetrahydrofuran-3-methanol (XXXIII), already obtained in Scheme 22656201c.

合成路线12

Reaction of L-aspartic acid (I) with trifluoroacetic acid and trifluoroacetic anhydride afforded N-trifluoroacetyl-L-aspartic anhydride (II). Then, Friedel-Crafts acylation of 1,3-difluorobenzene (III) with this anhydride in the presence of AlCl3 gave ketone (IV). The reduction of the carbonyl group of (IV) was effected by catalytic hydrogenation in the presence of Pearlman's catalyst, and the resulting phenylbutyric acid (V) was converted to acid chloride on treatment with PCl5 in cold dichloromethane, and subsequently cyclized by addition of AlCl3 to yield tetralone (VI). Hydrogenolysis of (VI) in the presence of Pearlman's catalyst gave tetrahydronaphthalene (VII), and further hydrolysis of trifluoroacetamide with LiOH yielded (S)-5,7-difluoro-1,2,3,4-tetrahydronaphthalen-2-yl amine (VIII). Imidazole ring was then constructed by treatment of this amine with 1,3-dihydroxyacetone (IX) and potassium thiocyanate in acidic medium, and the hydroxyl group of the resulting X was substituted by a formamido group by either heating in formamide at 175 C or with ammonium formate. Finally, formamide (XI) was hydrolyzed in refluxing isopropanolic HCl.

合成路线13

The acylation of m-difluorobenzene (I) with 2-bromoacetyl bromide (II) by means of AlCl3 gives the phenacyl bromide (III), which is treated with ethylmercaptan (IV) and K2CO3 to yield the sulfanyl derivative (V). The fluorination of (V) with N-fluoro-4-methylpyridinium-2-sulfonate affords the difluoroacetyl derivative (VI). The methylenation of the carbonyl group of (VI) with trimethylsulfoxonium iodide provides the oxiranyl derivative (VII), which is opened with 1,2,4-triazole (VIII) and K2CO3, furnishing the propanol derivative (IX). The oxidation of the sulfanyl group of (IX) by means of H2O2 or MCPBA gives the corresponding sulfonyl derivative (X). Finally, the racemic mixture (X) is submitted to optical resolution by crystallization of the (+)-3-bromocamphorsulfonic acid. Alternatively, intermediate (VI) can be obtained as follows: The reaction of 2-chloro-2,2-difluoroacetic acid ethyl ester (XI) with ethylmercaptan (IV) by means of NaH gives the sulfanyl derivative (XII), which is finally condensed with 2,4-difluorobromobenzene (XIII) by means of BuLi to afford the desired intermediate (VI).

合成路线14

The known chiral epoxide (IX) can be synthesized by several different ways shown in the following: 1) 2(S)-Acetoxypropionic acid (XII) is treated first with oxalyl chloride in DMF/CH2Cl2, and then the resultant acyl chloride is submitted to a Friedel-Crafts reaction with 1,3-difluorobenzene (XIII) by means of AlCl3 to provide a 1:1 mixture of a(S)-acetoxypropiophenone (XIV) and a(S)-hydroxy-propiophenone (XV). This mixture is treated with H2SO4 in MeOH to give the pure alcohol (XV). Tosylation of alcohol (XV) with p-toluenesulfonyl chloride in pyridine furnishes tosylate (XVI), which is converted into a(R)-hydroxypropiophenone (XVII) by an SN2 displacement reaction with LiOH in DMF/H2O. Reaction of the hydroxy group of (XVII) with 2,3-dihydropyran (XVIII) and pyridi-nium p-toluenesulfonate (PPTS) in CH2Cl2 gives the protected compound (XIX), which is converted into the silyl alcohol (XXI) by a Grignard reaction with (chloro-methyl)dimethylisopropoxysilane (XX) in the presence of Mg and a small amount of MeI. Oxidative desilylation of (XXI) by means of NaHCO3 and H2O2 in THF/MeOH, followed by hydrolysis with TsOH in MeOH, affords the triol (XXII), which is then mesylated with methanesulfonyl chloride in pyridine to provide the dimesylate (XXIII). Finally, nucleofilic substitution of one mesylate group of (XXIII) with 1H-1,2,4-triazole (XXIV) by means of NaH in DMF with concomitant epoxide formation affords the desired intermediate (IX).

合成路线15

Conversion of 4-hydroxy-L-proline (I) into the corresponding cis-N-Boc-4-hydroxy-L-proline methyl ester (II) is performed as follows: Treatment of (I) with SOCl2 in MeOH followed by reaction with Boc2O and Et3N in EtOAc affords the corresponding protected acid chloride; then the methyl ester moiety is formed under Mitsunobu conditions with formic acid, DIAD and PPh3 in THF followed by treatment with NaOH in MeOH. The OH group of (II) is converted into thioether (IV) by first mesylation with MsCl and Et3N in toluene followed by reaction with triphenylmethanethiol (III) in THF in the presence of NaH. Reduction of the methyl ester of (IV) with LiBH4 in THF provides alcohol (V), which is mesylated with MsCl and Et3N in THF and then treated with NaN3 and HMPA to furnish azide (VI). Boc removal in (VI) is performed by treatment with HCl in EtOAc to give derivative (VII), which is then converted into compound (VIII) by condensation with 2-(2,4-difluorobenzoyl)benzoic acid (XI) by means of water-soluble carbodiimide (WSC) and HOBt in DMF (compound (XI) can be obtained by Friedel-Crafts reaction between phthalic anhydride (IX) and 1,3-difluorobenzene (X) in the presence of AlCl3). Reduction of the azido moiety of (VIII) by means of SnCl2 and NaOH in EtOH furnishes amine (XII), which is finally converted into the desired product by condensation with carboxylic acid (XIII) by means of WSC and HOBt (derivative (XIII) can be obtained by Knoevenagel reaction between 4-formyl-benzoic acid (XIV) and 2,4-thiazolidinedione (XV) in refluxing 2-methoxyethanol in the presence of piperidine).

合成路线16