1-Phenyl-6,7-disubstituted-aminopropyl)-1,2,3,4-tetrahydroisoquinolines as possible antituberculer agents

The Condensation of 3,4-disubstituted phenylethylamine and benzaldehyde furnished l-phenyl-6,7-disubstituted-1,2,3,4-tetrahydroisoquinolines l. which on reaction with 1,3-dibromopropane gave l-phenyl-6,7-disubstituted-2-(3-bromoprophyl)-1,2,3,4-tetrahydroisoquinolines 2. The reaction of 2 with different secondary amines resulted in the synthesis of 3. The compounds 3 were screened for their in vitro antituberculer activity against Mycobacterium smegmatis, and some of them have been found to be total inhibitors of M. Smegmatis     

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 New Convenient Approach to Preparation of 5 or 6 or 7-Nitro-1,2,3,4-Tetrahydrisoquinolines and 2-Alkylsulfonyl-5 or 6 or 7-Nitro-1,2,3,4-Tetrahydroisoquinolines

N-alkylsulfonyl-p or m or o -nitrophenylethylamines were treated with (HCHO)n in 60% H₂SO₄/HOAc to give N-alkylsulfonyl-5 or 6 or 7-nitro-1,2,3,4-tetrahydroisoquinolines, then hydrolyzed with 40% HBr to give 5 or 6 or 7-nitro-1,2,3,4-tetrahydroisoquinolines     

Alkylation of N-boc-1,2,3,4-tetrahydroisoquinolines in the 1-position and its application to the synthesis of isoquinoline alkaloids

Boc-protected 1,2,3,4-tetrahydroisoquinolines 2 can be lithiated with t-butyllithium in the presence of N,N,N',N',-tetramethylethylenediamine. Reaction of the anion with alkyl halides provides 1-alkyl N-Boc-1,2,3,4-tetrahydroisoquinolines in 67–71% yield. The protecting group is easily removed in high yield with trifluoroacetic acid. The alkaloids salsolidine ( 8 ) and laudanosine ( 11 ) were synthesized in racemic form using this method.     

A Convenient Synthesis of 3-Aryl-2-Methyl-3,4-Dihydro-1(2H)-Isoquinolones and -1,2,3,4-Tetrahydroisoquinolines

A new methodology for the synthesis of 3-aryl-2-methyl-3,4-dihydro-2H-isoquinolin-l-ones and 3-aryl-2-methyl-1,2,3,4-tetrahydroisoquinolines is reported.     

Studies on Debenzylation and Photolysis of 1-Benzyl- and 1-(β-Phenethyl)-1,2,3,4-tetrahydroisoquinolines

Debenzylation of 1-(3-benzyloxybenzyl)-1,2,3,4-tetrahydroisoquinolines 1 , 6 , 7 with hydrochloric acid and ethanol gave the corresponding phenolic isoquinolines 2 , 8 , 9 and tetrahydroprotoberberines 4 , 12 , 13 . Compounds 2 , 8 , 9 on photolysis also gave, besides the expected noraporphines 3 , 10 , 11 , the tetrahydroprotoberberines 4 , 12 , 13 [1–4] (Schemes 1 and 2). 6-Benzyloxy-1-(5-benzyloxy-2-bromo-benzyl)-1,2,3,4-tetrahydroisoquinoline (27a) containing no methoxy or methylenedioxy groups either in ring A or C does not give protoberberine during debenzylation; but 28 , the debenzylation product of 27a , on photolysis gives both the noraporphine 29 and the tetrahydroprotoberberine 30 (Scheme 6), proving that during debenzylation of 1-(3-benzyloxybenzyl)-1,2,3,4-tetrahydroisoquinolines containing additional methoxy or methylenedioxy groups, the necessary formaldehyde comes from the latter groups. During photolysis both the methoxy groups (methylenedioxy groups) and the C(3) atom of the tetrahydroisoquinoline moiety provide the formaldehyde. Veratrole under debenzylation and photolytic conditions and tetrahydroisoquinoline under the latter condition also give rise to formaldehyde (Schemes 8 and 10). The novel bromohomoprotoberberine 43 along with 42 was formed during debenzylation of the 1-phenethyl-1,2,3,4-tetrahydroisoquinoline 41 . Photolysis of 42 yielded the novel nor-homoaporphine 44 , in addition to 43 ; the latter was debrominated to give the homoberbine 45 .     

New isoquinolines as potential bronchodilator agents

The syntheses of 5-hydroxy-6-hydroxymethyl, 6-hydroxy-7-hydroxymethyl and 7-hydroxy-6-hydroxymethyl-1-(3,4,5-trimethoxybenzyl)-1,2,3,4-tetrahydroisoquinolines (1d), (1b) and (1c) respectively, are described.     

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%.     

Synthesis of 6,7-dimethoxy-1-[(halophenoxy)-methyl]-1,2,3,4-tetrahydroisoquinolines

Some 6,7-dimethoxy-1-[(halophenoxy)methyl]-1,2,3,4-tetrahydroisoquinolines were synthesized from N-[2-(3,4-dimethoxyphenyl)ethyl]-2-chloroacetamide via three steps in good yield.     

Quinone methide initiated cyclization reaction: synthesis of 4-aryl-1,2,3,4-tetrahydroisoquinolines

4-Aryl-1,2,3,4-tetrahydroisoquinolines were synthesized in very good yields by in situ generation of p-quinone methides resulting in a novel C-C bond formation.     

Tungstophosphoric acid catalyzed synthesis of N-sulfonyl-1,2,3,4-tetrahydroisoquinoline analogs

An operationally simple and eco-friendly protocol has been developed for the synthesis of N-sulfonyl-1,2,3,4-tetrahydroisoquinolines 3 using the modified Pictet-Spengler reaction of N-sulfonylphenylethylamines 1 and various aldehydes 2 in the presence of tungstophosphoric acid hydrate.     

A convenient synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines via Pictet-Spengler reaction using titanium(IV) isopropoxide and acetic-formic anhydride

A synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines (6) was achieved in a highly efficient manner via Pictet-Spengler reaction of arylethylamines (1) and acyclic and cyclic ketones (2) using titanium (IV) isopropoxide and acetic-formic anhydride. The cyclization of the in situ formed acyliminium ion (4) to N-formyl 1,2,3,4-tetrahydroisoquinoline (5) was greatly facilitated by using trifluoroacetic acid as an additional reagent. The Pictet-Spengler reaction was carried out by one pot procedure, providing a convenient and effective method for preparing various 1,2,3,4-tetrahydroisoquinolines.     

Saturated heterocycles. 57. Synthesis of 4-substituted-9,10-dialkoxy-1,6,7,11b-tetrahydro-2H-pyrimido[6,1-a]isoquinolin-2-ones

A large number of 4-substituted-9,10-dialkoxy-1,6,7,11b-tetrahydropyrimido[6,1-a]isoquinolin-2-ones were prepared by the reaction of 1-(ethoxycarbonylmethyl)-6,7-dialkoxy-1,2,3,4-tetrahydroisoquinolines with iminoethers. Reaction of the corresponding isoquinoline-1-acetic acid derivatives with iminoethers led to the formation of N-acyl-1,2,3,4-tetrahydroisoquinolin-1-acetamides. In the hydrolysis of the prepared 4-substituted-pyrimido[6,1-a]isoquinolin-2-ones, the corresponding N-acyl-1,2,3,4-tetrahydroisoquinolin-1-acetamides were obtained. While reduction of the 4-phenyl derivative resulted in the corresponding 1,3,4,6,7,11b-hexahydropyrimidinone. The steric structures of the tetrahydro- and hexahydropyrimido[6,1-a]isoquinolines were determined by nmr spectroscopy.     

Pd/C促进的四氢异喹啉高选择性部分脱氢(英文)

采用K3PO4?3H2O修饰的Pd/C为催化剂实现了取代四氢异喹啉高选择性部分脱氢,并成功地避免了当量有害氧化剂的使用.多相催化剂Pd/C对四氢异喹啉化合物具有催化脱氢活性,但反应选择性较差,同时产生完全脱氢的芳构化产物异喹啉.而K3PO4?3H2O修饰的Pd/C催化剂能有效提高脱氢反应的化学选择性,在最优条件下可获得最高89%的分离收率.这为取代3,4-二氢异喹啉的合成提供了一种简便、高原子经济性和高化学选择性的反应途径.此外,该多相催化剂可回收循环使用多次,且活性和选择性基本保持不变.     

A general procedure for the asymmetric synthesis of 3-aryl-1,2,3,4-tetrahydroisoquinolines

A general procedure for the asymmetric synthesis of 3-aryl-1,2,3,4-tetrahydroisoquinolines with any desired substitution pattern at both aromatic rings is reported. The methodology relies on the deoxygenation of 3-aryl-1,2,3,4-tetrahydroisoquinolin-4-ols 1a–e, which can be easily prepared from chiral non-racemic arylglycines under ionic hydrogenation conditions The target heterocycles are obtained as almost enantiomerically pure compounds. Further experiments allow establishing that this transformation occurs via S_N1 mechanism in which a carbocationic intermediate species is firstly formed and afterwards it undergoes rapid reaction with a nucleophilic hydride carrier to afford the reduction product.     

Oxazoline as a useful tool in organic synthesis: preparation of 4-aryl-1,2,3,4-tetrahydroisoquinoline alkaloid skeleton

New direct strategy for the synthesis of 4-aryl-1,2,3,4-tetrahydroisoquinolines. The key steps are based on oxazoline chemistry: nucleophilic substitution in an ortho-methoxyphenyloxazoline with a Grignard reagent and a 1,6-conjugate addition of a lithium amide to o-styrylphenyloxazoline.     

Synthesis of 1,2,3,4-tetrahydroisoquinolines and 2,3,4,5-tetrahydro-1H-2-benzazepines combining sequential palladium-catalysed ortho alkylation/vinylation with aza-Michael addition reactions

1-Substituted 1,2,3,4-tetrahydroisoquinolines and 2,3,4,5-tetrahydro-1H-2-benzazepines were synthesised from o-iodoalkylbenzene, N-Cbz-bromoalkylamine and an electron-poor olefin through a one-pot palladium-catalysed sequence involving ortho alkylation, alkenylation and intramolecular aza-Michael reaction.     

Controlling stereoselectivity by enzymatic and chemical means to access enantiomerically pure (1S,3R)-1-benzyl-2,3-dimethyl-1,2,3,4-tetrahydroisoquinoline derivatives

A chemoenzymatic strategy for the synthesis of enantiomerically pure novel alkaloids (1S,3R)-1-benzyl-2,3-dimethyl-1,2,3,4-tetrahydroisoquinolines is presented. The key steps are the biocatalytic stereoselective reductive amination of substituted 1-phenylpropan-2-one derivatives to yield chiral amines employing microbial ω-transaminases, and the diastereoselective reduction of a Bischler–Napieralski imine intermediate by catalytic hydrogenation in the presence of palladium on charcoal, leading exclusively to the desired cis-isomer.     

Synthesis and acylation of tertiary enamines: 1,2,3,4-tetrahydroisoquinoline derivatives

N-methyl-3,3-R¹R²-1-(R³-methylene)-1,2,3,4-tetrahydroisoquinolines were obtained; they react with acylating agents forming enaminocarbonyl derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 939–942, July, 1988.     

A New Approach to Prepare 2-Acetyl-Mono (5,6,7,8)-Nitro-1,2,3,4-Tetrahydroisoquinolines

N-Acetyl-p, m or o-nitro-phenylethylamines and (HCHO)n were treated in 60% H2SO4/HOAc, via α-amidoalkylation to give 2-acetyl-mono(5, 6, 7 or 8)-nitro-1,2,3,4-tetrahydro-isoquinolines.Additionally, some interesting phenomena were observed when the comparison between 2-acetyl-5, 6, 7 or 8-nitro-1,2,3,4-tetrahydroisoquinolines and 2-alkylsulfonyl-5 , 6 or 7- nitro-1,2,3,4-tetrahydroisoquinolines was made.