Stereoselective synthesis of 3-mono- and 1,3-disubstituted 4-phenyl-1,2,3,4-tetrahydroisoquinolines

(1S,2S)-(+)-Thiomicamine was transformed in high yield and with high diastereoselectivity into (3R,4R)-4-phenyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid and enantiomerically pure (3R,4R)-3-hydroxymethyl-4-phenyl- and (1R,3R,4R)-3-hydroxymethyl-1-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinoline derivatives.     

A comparative study on the acylative kinetic resolution of racemic fluorinated and non-fluorinated 2-methyl-1,2,3,4-tetrahydroquinolines and 3,4-dihydro-3-methyl-2H-[1,4]benzoxazines

The acylative kinetic resolution of racemic 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline, 7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine, and their non-fluorinated analogues with (S)-naproxen and N-phthaloyl-(S)-amino acyl chlorides has been carried out. It has been shown that the presence of fluorine atoms in the aromatic fragment of a heterocyclic amine results in the increasing stereoselectivity of acylation with (S)-naproxen acyl chloride and in a decrease in the efficiency of acylative kinetic resolution using N-phthaloyl-(S)-amino acyl chlorides. A method for the preparation of enantiopure (S)-6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (ee >99%) was developed.     

Synthesen von 4-Amino-5,6-dihydro-4H-pyrido[3,2,1-j k]-carbazol, 1-Phenyl-4-amino-1,2,3,4-tetrahydrochinolin und deren Derivaten

Zusammenfassung Die Ringschlußreaktion von Carbazol-N-propionsäure ergab 4-Oxo-5,6-dihydro-4H-pyrido[3,2,1-j k]carbazol, dessen Oxim zur 4-Aminoverbindung reduziert wurde. Ähnlich wurden 1-Phenyl-1,2,3,4-tetrahydrochinolin und einige seiner in 4-Stellung substituierten Derivate über das 1-Phenyl-4-oxo-1,2,3,4-tetrahydrochinolin dargestellt: Reduktion gab den Grundkörper, der auch durch Entschwefelung von entsprechenden Heterocyclen erhalten wurde; Nebenreaktionen werden beschrieben. Umsetzung zum Oxim und Reduktion gab 1-Phenyl-4-amino-1,2,3,4-tetrahydrochinolin. Dieses wurde mit Acrylsäuremethylester zu 1-Phenyl-4-(-carbomethoxyäthyl-amino)-1,2,3,4-tetrahydrochinolin, mit -Propiolacton zu 1-Phenyl-4-(-hydroxypropionyl-amino)-1,2,3, 4-tetrahydrochinolin umgesetzt; beide Substanzen wurden durch LiAlH₄ zu 1-Phenyl-4-(-hydroxypropyl-amino)-1,2,3,4-tetrahydrochinolin reduziert.

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Ring closure reaction of carbazole-N-propionic acid gave 4-oxo-5,6-dihydro-4H-pyrido[3,2,1-j k]carbazole, the oxime of which was reduced to the 4-amino compound. Similarly 1-phenyl-1,2,3,4-tetrahydroquinoline and some derivatives thereof (substituted in position 4) were synthesized via 1-phenyl-4-oxo-1,2,3,4-tetrahydroquinoline: reduction gave the tetrahydroquinoline, which also was synthesized by desulfuration of corresponding heterocyclic systems; by-reactions are described. Reduction of the oxime gave 1-phenyl-4-amino-1,2,3,4-tetrahydroquinoline. The latter reacted with methyl acrylate to 1-phenyl-4-(carbomethoxyethyl-amino)-1,2,3,4-tetrahydroquinoline, with -propiolactone to 1-phenyl-4-(-hydroxypropionyl-amino)-1,2,3,4-tetrahydroquinoline, both of which were reduced by LiAlH₄ to 1-phenyl-4-(-hydroxypropylamino)-1,2,3,4-tetrahydro quinoline.

     

Asymmetric synthesis of (1R,2S,3R)-2-acetyl-4-(1,2,3,4-tetrahydroxybutyl)thiazole

Two different methods for preparing the thiazole analogue 3 of the biologically active compound (1R,2S,3R)-2-acetyl-4(5)-(1,2,3,4- tetrahydroxybutyl)imidazole 1 are reported.     

Kinetic resolution of racemic 2-methyl-1,2,3,4-tetrahydroquinoline and its structural analogs by using 2-arylpropionyl chlorides

Acylation of 2-methyl-1,2,3,4-tetrahydroquinoline and 2-methylindoline with the acyl chlorides of naproxen, ibuprofen, and 2-phenylpropionic acid has been found to lead to efficient kinetic resolution with predominant formation of the (S,S)-(R,R)-diastereoisomers. The highest acylation stereoselectivity was found in toluene at -20°C. No significant kinetic resolution of N-(sec-butyl)aniline and 2-methylpiperidine was achieved by using 2-arylpropionyl chlorides.     

An efficient synthesis of optically pure (S)-2-functionalized 1,2,3,4-tetrahydroquinoline

Using a copper-catalyzed coupling reaction of amino acid and aryl halide, followed by intramolecular cyclization of N-aryl-1-hydroxyl-3-propylamines under the Swern’s condition as the key steps, (S)-2-hydroxymethyl-1,2,3,4-tetrahydroquinoline was synthesized as an example of optically pure 2-functionalized 1,2,3,4-tetrahydroquinolines.     

Synthesis of enantiomers of 6-nitro- and 6-amino-2-methyl-1,2,3,4-tetrahydroquinolines

Enantiomers of 2-methyl-6-nitro-1,2,3,4-tetrahydroquinoline have been obtained by kinetic resolution of racemic 2-methyl-1,2,3,4-tetrahydroquinoline in acylation with acyl chlorides of N-protected amino acids followed by regioselective nitration of the diastereoisomeric amides and acidic hydrolysis. The introduction of a trifluoroacetyl protecting group into the position 1 of the enantio pure nitro compound followed by the reduction led to (S)-6-amino-2-methyl-1-trifluoroacetyl-1,2,3,4-tetra-hydroquinoline in a high yield.     

Synthesis and Stereochemistry of 4-Amino-2-Phenyl-1,2,3,4-Tetrahydroquinoline

Cis and trans-isomers of the 4-amino-2-phenyl-1,2,3,4-tetrahydroquinoline were synthesized. The relative stereochemistry of the isomers was determined by ¹H-NMR.     

A concise and stereospecific synthesis of some cyclitols containing eight-membered rings: cyclooctane-1,2,3,4-tetraoles

A concise and efficient synthesis of cyclooctane-1,2,3,4-tetraoles, new polyhydroxylated eight-membered carbocycles, is described starting from cis,cis-1,3-cyclooctadiene. Cyclooctene endoperoxide obtained by photooxygenation of cis,cis-1,3-cyclooctadiene was the key compound in the synthesis. Reduction of the endoperoxide with zinc or thiourea followed by acetylation of the hydroxyl group and OsO₄/NMO oxidation of the double bond gave (1R(S),2S(R),3R(S),4S(R))-cyclooctane-1,2,3,4-tetraol. Interestingly, epoxidation of cyclooctene-1,4-diol with m-CPBA also afforded trans-epoxy-diol 17. (1R(S),2R(S),3R(S),4S(R))-cyclooctane-1,2,3,4-tetraol was easily obtained by hydrolysis of epoxy-diol 17.     

Stereocontrolled metalloenamine alkylations: application to the asymmetric synthesis of 4-alkyl-1,2,3,4-tetrahydroisoquinolines

A procedure for the asymmetric synthesis of 4-alkyl-1,2,3,4-tetrahydroisoquinolines is described. The key step in the synthetic route is a stereocontrolled metalloenamine alkylation using (R)-(+)-phenylglycinol methyl ether as the chiral auxiliary. Subsequent N-methylation, hydrogenolysis and cyclization afforded the target heterocycles with enantiomeric excesses higher than 99%.     

Enantiopure vic-amino alcohols and vic-diamines from (1R,2S)-1,2-dihydroxy-1,2-dihydronaphthalene

(1S,2S)-2-Hydroxy-1-amino-1,2,3,4-tetrahydronaphthalene, (1R,2R)-1-hydroxy-2-amino-1,2,3,4-tetrahydronaphthalene, (1S,2R)-1,2-diamino-1,2,3,4-tetrahydronaphthalene, (2R,3S)-2-hydroxy-3-amino-1,2,3,4-tetrahydronaphthalene and (2S,3S)-2,3-diammino-1,2,3,4-tetrahydronaphthalene have been synthesized from (1R,2S)-1,2-dihydroxy-1,2-dihydronaphthalene. The latter was obtained, using a protocol reported in a previous paper, from naphthalene using an Escherichia coli recombinant strain containing the naphthalene dioxygenase gene cloned from Pseudomonas fluorescens N3.     

Photochemical synthesis of 1,2,3,4-tetrahydroisoquinolin-3-ones from N-chloroacetylbenzylamines

When N-chloroacetyl-3-hydroxybenzylamine (37) in aqueous acetonitrile was irradiated, both ortho and para photocyclizations with reference to the OH group occurred to give 7- and 5-hydroxy-3-oxo-1,2,3,4-tetrahydroisoquinolines (52,53). Similarly, 1-methylisoquinoline derivatives (54,55) were synthesized. N-Chloroacetyl-3,5-dihydroxybenzylamine (39) gave a single photoproduct, 5,7-dihydroxy-3-oxo-1,2,3,4-tetrahydroisoquinoline (56). These photocyclizations were smoothly extended to the synthesis of 1-benzyl, 1-(4′-methoxybenzyl)- and 1-(3′,4′,5′-trimethoxybenzyl)-isoquinoline derivatives (58～64).     

Chiral aziridine-2-carboxylates: versatile precursors for functionalized tetrahydroisoquinoline (THIQ) containing heterocycles

Preparation of functionalized 3,4-dihydroisoquinolines 17a–j from (S)-N-methoxy-N-methyl-1-[(R)-1-phenylethyl]aziridine-2-carboxamide 4 is an effective route for the synthesis of 3-(hydroxymethyl)-1,2,3,4-tetrahydroisoquinolin-4-ols. Stereoselective reduction of the cyclic imines 17a–j resulted in (1S,3S,4R)-4-(tert-butyldimethylsilyl-oxy)-3-[(tert-butyldimethylsilyloxy)methyl]-6,7-dimethoxy-1,2-disubstituted-1,2,3,4-tetrahydroisoquinolines and the desilylation of the TBS groups afforded (1S,3S,4R)-3-(hydroxymethyl)-6,7-dimethoxy-1,2-disubstituted-1,2,3,4-tetrahydroisoquinolin-4-ols 19a–i in good yields. Also, an asymmetric synthesis of novel tetracyclic 3-(hydroxymethyl)-1,2,3,4-tetrahydroisoquinolin-4-ols 23 and 25 was successfully achieved via Pd-catalyzed N-arylation and C–C coupling reaction.     

A stereoconvergent synthesis of (+)-4-demethoxydaunomycin

Sharpless kinetic asymmetric epoxidation on (±)-2-(l-hydroxyethyl)-5,8-dimethoxy-3,4-dihydronaphthalene (8) followed by LAH reduction gave R-2-(S-l-hydroxyethyl)-2hydroxy-5,8-dimethoxy-1,2,3,4-tetrahydronaphthalene and the undesired antipode. The former was converted to R-(-)-2-acetyl-2 hydroxy-5,8-dimethoxy-l,2,3,4-tetrahydronapthalen[R-(-)-5],while the latter was epimerized and recycled. R-(-)-5 has been exploited for the synthesis of(+)-4-demethoxydaunomycin     

Efficient construction of 1,2-dihydroquinoline and 1,2,3,4-tetrahydroquinoline rings using tandem Michael-aldol reaction

1,2-Dihydroquinolines and a 1,2,3,4-tetrahydroquinoline were efficiently constructed using tandem Michael-aldol reaction starting from N-protected o-aminobenzaldehydes and α,β-unsaturated carbonyl compounds in good yield.     

Enantioseparation of 1-Phenyl-1,2,3,4-tetrahydroisoquinoline on Polysaccharide-Based Chiral Stationary Phases

The enantiomers of 1-phenyl-1,2,3,4-tetrahydroisoquinoline have been directly separated on polysaccharide-based chiral stationary phases (CSPs). The normal phase separation of (S)- and (R)-1-phenyl-1,2,3,4-tetrahydroisoquinoline was accomplished by screening of the immobilized Chiralpak IC column with different eluents. The effect of mobile phase type on retention, selectivity and resolution was studied. 2-Propanol or ethanol/n-hexane/ethanolamine mixtures were applied as mobile phases by screening of following polysaccharide-based immobilized (Chiralpak IA, Chiralpak IC) and coated (Lux Cellulose-1, Lux Cellulose-2, Lux Amylose-2) CSPs. Polar organic and reversed-phase conditions were also tested for direct enantioseparation of 1-phenyl-1,2,3,4-tetrahydroisoquinoline.     

A contribution to the asymmetric synthesis of isoquinolines: Concise stereoselective approach to (3S,4S)-6,7-dimethoxy-4-hydroxy-3-phenyl-1,2,3,4-tetrahydroisoquinoline

A highly efficient stereoselective synthesis of (3S,4S)-6,7-dimethoxy-4-hydroxy-3-phenyl-1,2,3,4-tetrahydroisoquinoline 8 (e.e.=96%) starting from enantiomerically pure imine 3 is reported.     

Five-membered 2,3-dioxo heterocycles: CII. Spiro heterocyclization of 3-aroylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones by the action of tetrahydroquinoline

3-Aroylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with 1,2,3,4-tetrahydroquinoline to give 3-aroyl-4-hydroxy-1-(2-hydroxyphenyl)-5′,6′-dihydrospiro[pyrrole-2,1′-pyrrolo[3,2,1-ij]quinoline]-2′,5(1H,4′H)-diones.     

两相体系中羟化酶催化-1,2,3,4-四氢喹啉不对称羟基化反应

以菌株Pseudomonas plecoglossicidas ZMU-T02整细胞为生物催化剂,1,2,3,4-四氢喹啉经不对称羟基化反应合成了(R)-4-羟基-1,2,3,4-四氢喹啉,其结构经¹H NMR, ¹³C NMR, HR-MS和HPLC确证。在细胞浓度为30 g cdw·L^-1, pH为9.0,整细胞悬浮液/有机溶剂比例为1 ：1的两相体系中,底物浓度为10 mmol·L^-1时,收率37%, ee值98%。     

Chemoenzymatic synthesis of the enantiomerically pure 1,2,3,4-tetrahydroquinoline moiety of the antithrombotic (21R)- and (21S)-argatroban

The synthetic antithrombotic argatroban is a dipeptide between the nonproteogenic (2R,4R)-4-methyl-2-piperidine carboxylic acid and l-arginine, in turn bonded to a 3-methyltetrahydroquinoline sulfonyl group; the drug is usually prepared and administered as a mixture of C-21-diastereoisomers. By means of a biocatalytic transformation enantiomerically pure (R)- and (S)-synthons, suitable for the synthesis of separate (21R)- and (21S)- argatroban, were obtained.