First nucleophilic aromatic substitution of annelated pyrazole.

3-Chloropyrazolo[3,4-c]quinoline 5, 3-chloropyrazolo[3,4-c]isoquinoline 6, 1,2-dihydro-1,2-dimethylpyrazolo[3,4-c]quinolin-3-one 8, and 1,2-dihydro-1,2-dimethylpyrazolo[3,4-c]isoquinolin-3-one 10 were obtained by acid-induced nucleophilic aromatic substitution (S(N)H) of H-3 in N-hydroxypyrazolo[3,4-c]quinoline 1b and in N-hydroxy pyrazolo[3,4-c]isoquinoline 3b. In the acid-induced chlorination, 3b was far more reactive than 1b, whereas the related N-hydroxypyrazolo[4,3-c]quinoline 2b and N-hydroxypyrazolo[4,3-c]isoquinoline 4b were completely unreactive toward S(N)H under identical conditions.     

Synthesis and reactivity of some imidazo‐, triazolo‐ and tetrazolo‐isoquinoline derivatives

1‐Acetylirrüno‐3‐methyl‐1H‐isochromene‐4‐carbonitrile, 1 , reacts with glycine ethyl ester under basic conditions to give an imidazo[2,1‐a]isoquinoline derivative, while reaction with hydrazine hydrate in 1,4‐dioxane, with further chemistry, provides access to [1,2,4]triazolo[5,1‐a]isoquinoline, [1,2,4]triazolo[3,4‐a]isoquinoline and tetrazolo[5,1‐a]isoquinoline analogs. Benzene ring nitration and radical bromination of substituent methyl groups were investigated in the four tricycles, with some different positional reactivities being found. Two bromomethyl derivatives so produced were oxidised; ethyl 2‐bromomethyl‐6‐cyano‐5‐methylimidazo[2,1‐a]isoquinoline‐3‐carboxylate gave the anticipated ethyl 6‐cyano‐2‐formyl‐5‐methylimidazo[2,1‐a]isoquinoline‐3‐carboxylate (which reacted further with hydrazine to form a new system, 8,9‐dihydro‐6‐methyl‐8‐oxopyridazino[4′,5′:4,5]imidazo[2,1‐a]isoquinoline‐5‐carbonitrile), while 5‐bromomethyl‐2‐methyl[1,2,4]triazolo[5,1‐a]isoquinoline‐6‐carbonitrile unexpectedly gave directly another new system, 5,6‐dihydro‐5‐hydroxy‐2‐methyl‐7H‐pyrrolo[3,4‐c][1,2,4]triazolo[5,1‐a]isoquinolin‐7‐one.     

2-Quinolyl- and 1-isoquinolylnitrenes: ring expansion and ring opening in heteroarylnitrenes

Argon matrix photolysis of tetrazolo[1,5-a]quinoline 8 and tetrazolo[5,1-a]isoquinoline 7 causes nitrogen elimination and ring expansion to 1,3-diazabenzo[d]cyclohepta-1,2,4,6-tetraene 13. The photolysis of tetrazolo[5,1-a]isoquinoline 7 also causes ring opening to o-cyanophenylketenimine 22. Mechanisms of ring opening of heteroarylnitrenes are discussed.     

Reaction of 1,2,3,4-tetrahydro-isoquinoline enamines with quinones

The reaction of p-benzoquinone with enamino amides derived from 2,2-dimethyl-1,2,3,4-tetrahydrobenzo[f]isoquinoline proceeds through a Michael addition. The reaction of this quinone with the base of drotaverine leads to a derivative of indolo[2,1-a]isoquinoline. Fusion of isoquinoline enamines by the action of 2,3-dichloro-1,4-naphthoquinone leads to pentacyclic benzo[g]naphtho-[2,3-b]indolyzine-8,13-dione. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1565–1570, October, 2006.     

Synthesis of 3-methyl-3,4-dihydroisoquinolines based on myristicin

The reaction of a natural allylbenzene, myristicin, with nitriles afforded a series of 7,8-dihydro-[1,3]dioxolo[4,5-g]isoquinoline and 6,7-dihydro[1,3]dioxolo[4,5-h]isoquinoline derivatives.     

The reaction of isoquinoline and dimethyl acetylenedicarboxylate with 1,2- and 1,4-benzoquinones: a novel synthesis of spiro[1,3]oxazino[2,3-a]isoquinolines

The 1,4-dipolar intermediate generated by the addition of isoquinoline to dimethyl acetylenedicarboxylate is trapped by 1,2- and 1,4-benzoquinones to afford spiro[1,3]oxazino[2,3-a]isoquinoline derivatives in high yields.     

Enamines of the 1,2,3,4-tetrahydroiso-quinoline series in the Chichibabin synthesis of pyrrolo[2,1-a]isoquinolines and in reaction with oxalyl chloride

It has been shown that the Chichibabin reaction of enamines of the 1,2,3,4-tetrahydroisoquinoline series and 1,2,3,4-tetrahydrobenzo[f]isoquinoline series with p-bromophenacyl bromide leads to pyrrolo[2,1-a]isoquinoline derivatives. The same heterocyclic system is obtained on interaction of 1-alkyl-3,4-dihydroisoquinolines or their benzo[f]-analogs with oxalyl chloride. The obtained dioxopyrrolines form derivatives of benzo[g]quinoxalino[2,3-b]indolizine on condensation with o-phenylenediamine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1068–1074, July, 2007.     

A Three‐Component Reaction for the Efficient Construction of the 2′,11b′‐Dihydrospiro[indoline‐3,1′‐pyrido[2,1‐a]isoquinoline] Skeleton

The three‐component reactions of isoquinoline, acetylenedicarboxylates, and 3‐phenacylideneoxindoles in ethanol at room temperature resulted in a mixture of two diastereoisomers of 2′,11b′‐dihydrospiro[indoline‐3,1′‐pyrido[2,1‐a]isoquinoline] derivatives, which were successfully separated and characterized. The regioselectivity and diastereoselectivity of this reaction were briefly discussed.     

Efficient One-pot Synthesis of Pyrrolo[2,1-a]isoquinoline and Pyrrolo[1,2-a]quinoline Derivatives

A one-pot sequential reaction for efficient synthesis of pyrrolo[2,1-a]isoquinoline and pyrrolo[1,2-a]-quinoline derivatives has been developed. The reaction included firstly the Cu-catalyzed three-component reaction of isoquinoline(quinoline), acetylenedicarboxylate and alkynylbenzene and then Cs₂CO₃-promoted intramolecular cyclization reaction of initially formed 1-alkenyl-2-alkynyl-1,2-dihydroisoquinoline(1,2-dihydroquinoline).     

Three-component reactions involving quinoline or isoquinoline,dialkyl acetylenedicarboxylate and β-trifluoroacetyl vinyl ethyl ether

The three-component reactions (TCRs) involving quinoline or isoquinoline, dialkyl acetylenedicarboxylate and β-trifluoroacetyl vinyl ethyl ether were investigated. The reaction proceeded smoothly under ambient temperature in DMSO to give the 4-trifluoroacetyl substituted benzo[c]quinolizine derivatives in moderate yields. However, under the same reaction condition, isoquinoline afforded the 2-trifluoromethyl substituted 1-oxa-(11H)-benzo[a]dihydroquinolizine or 4-trifluoroacetyl substituted benzo[a]dihydroquinolizine products. The possible reaction pathways were proposed.     

Reaction of N-Heterocycles with Acetylenedicarboxylates in the Presence of N-Alkylisatins or Ninhydrin. Efficient Synthesis of Spiro Compounds

Summary. The 1,3-dipolar intermediates generated by addition of isoquinoline, to dialkyl acetylenedicaboxylates are trapped by N-alkylisatins to produce dialkyl 1,2-dihydro-2-oxo-1-alkylspiro[3H-indol-3,2′-[2H,11bH][1,3]oxazino[2,3-a]isoquinoline]-3′,4′-dicarboxylates in excellent yields. The reaction of isoquinoline, quinoline, or pyridine with dimethyl acetylenedicarboxylate in the presence of ninhydrin led to dimethyl 1,2-dihydro-1,3-dioxospiro[3H-indene-3,2′-[2H,11bH][1,3]oxazino[2,3-a]isoquinoline]-3′,4′-dicarboxylate, dimethyl 1,2-dihydro-1,3-dioxospiro[3H-indene-3,3′[3H,4aH][1,3]oxazino[3,2-a]quinoline]-1,2-dicarboxylate, or dimethyl 1,2-dihydro-1,3-dioxospiro[3H-indene-3,2′-[2H,9aH]pyrido[2,1-b][1,3]oxazino]-3,4-dicarboxylate.     

Reactions of 4-cyanobenzo[<Emphasis Type="Italic">c</Emphasis>]pyrylium salts with nitrogen-containing nucleophiles

The recyclization reactions of 4-cyanobenzo[c]pyrylium salts with ammonia, primary amines, and hydrazines have been studied. New derivatives of isoquinoline, benzo-2,3-diazepine, and pyrazolo-[ 5,4-c]isoquinoline have been obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1645–1651, November, 2004.     

First synthesis of thiazepino[3,4-a]isoquinolines,a facile new synthetic route to diazepino[3,4-a]isoquinolines and assessment of their dopamine and σ receptor affinities

Heterocycles that bear the novel 5,6,14,14a-tetrahydro-8H-benzo[6,7][1,4]thiazepino[3,4-a]isoquinoline and the 5,6,14,14a-tetrahydro-8H-13l2-benzo[6,7][1,4]diazepino[3,4-a]isoquinoline frameworks were synthesized in a facile manner. These tetrahydroprotoberberine (THPB)-inspired scaffolds demonstrate selective affinity for the σ₁R in contrast to the naturally occurring THPB congeners that show D₁R and σ₂R selectivity.     

Synthesis of 6-methyl-6H-indolo[3,2-c]isoquinoline and 6-methyl-6H-indolo[2,3-c]isoquinoline: two new unnatural isoquinoline isomers of the cryptolepine series

11H-indolo[3,2-c]isoquinoline has been synthesized in two steps starting from 4-bromoisoquinoline and 2-bromoaniline via a selective Buchwald-Hartwig reaction followed by a Pd-catalyzed intramolecular direct arylation involving C(sp²)-H activation. The synthesis of 7H-indolo[2,3-c]isoquinoline was achieved by a combination of a Suzuki reaction with an intramolecular nitrene insertion reaction starting from 4-bromoisoquinoline and {2-[(2,2-dimethylpropanoyl)amino]phenyl}boronic acid. Selective methylation of the tetracyclic skeletons yielded the title compounds 6-methyl-6H-indolo[3,2-c]isoquinoline and 6-methyl-6H-indolo[2,3-c]isoquinoline, which have never been described in the literature before.     

A novel multicomponent reaction involving isoquinoline,allenoate and activated ketone

The reaction of isoquinoline and allenoate with activated ketone resulted in a novel three component reaction, affording [1,3]oxazino[2,3-a]isoquinoline derivatives in moderate yields along with moderate diastereoselectivities via 1,4-dipolar cycloaddition. It was also found that when isatins were used as substrates, the regioselectivity of cycloadducts was different from those using ethyl trifluoropyruvate as substrate.     

Synthesis of derivatives of the new heterocyclic systems benz[f] imidazo [2,1 -a ] isoquinoline and benz [f] pyrimido [2,1 -a] isoquinoline

The synthesis of several derivatives of benz [f] imidazo [2,1 -a] isoquinoline and benz [f] pyrimido-[2,l-a]isoquinoline, both new heterocyclic structures, is described.     

Reaction of 1-aminomethyl-1,2,3,4-tetrahydroisoquinoline with diethyl fumarate

The reaction of 1-aminomethyl-1,2,3,4-tetrahydroisoquinoline with diethyl fumarate goes by two possible paths, to form a mixture of 3-carbethoxymethyl-4-oxo-1,2,3,6, 7,IIb-hexahydro-4H-pyrazino[2,1-a]isoquinoline and its isomer 4-carboxymethyl-3-oxo-1,2,3,6,7-llb-hexahydro-4H-pyrazino[2,1-a]isoquinoline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 798–800, June, 1985.     

Synthesis of indolo[2,1-a]isoquinolines by CF3COOH-induced cyclization

Indolo[2,1-a]isoquinoline alkaloids and related compounds have been known to have interesting biological activities, such as antileukemic and antitumor activities. We found that 1-(3,4-dimethoxyphenethyl)indole gave 2,3-dimethoxyindolo[2,1-a]isoquinoline and 1-(3,4-dimethoxyphenylacetyl)indole gave 2,3-dimethoxy-6-oxoindolo[2,1-a]isoquinoline, respectively, by an intramolecular cyclization carried out in boiling trifluoroacetic acid.     

Facile Access to Benzothiazole‐Containing Pyrrolo[1,2‐a]quinolines and Pyrrolo[2,1‐a]isoquinolines via Nitrogen Ylides

Quinoline and isoquinoline react with 2‐(bromoacetyl)benzothiazole ( 1 ) in dry benzene to give the corresponding quinolinium and isoquinolinium salts 2 and 10 which undergo base‐mediated [3+2] 1,3‐dipolar cycloaddition with some acetylene and ethylene derivatives to give the corresponding benzothiazole‐containing pyrrolo[1,2‐a]quinoline and pyrrolo[2,1‐a]isoquinoline derivatives.     

Synthesis of phenanthro[2,3-h]isoquinoline and phenanthro[3,2-h]isoquinoline

The suspected environmental contaminants phenanthro[2,3-h]isoquinoline 12 and phenanthro[3,2-h]isoquinoline 11 were synthesized in four steps from a common intermediate 1,4-phenanthroquinone 3 , using a Diels-Alder reaction.