The synthesis of isoquinolines, indoles and benzthiophen by an improved Pomeranz-Fritsch reaction, using boron trifluoride in trifluoroacetic anhydride

Bevis, M.J.; Forbes, E.J.; Naik, Nagaraja; Uff, B. C.

doi:10.1016/s0040-4020(01)90874-9

Cited by 48 publications

(22 citation statements)

References 25 publications

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“…11 When 21 was treated with the acid chloride 19 in THF at -23 o C and stirred for 1h a precipitate was formed (presumably an isoquinolinium quaternary salt) which redissolved on the addition of methylmagnesium iodide. Chromatography of the crude product gave 22 in good yield (92%).…”

Section: Methodsmentioning

confidence: 99%

“…After 3h the mixture was filtered through a thin pad of silica and washed with methanol (20 mL). The filtrate was concentrated and purified by radial preparative layer chromatography to yield (±)-O-methylcorytenchirine (390 mg, 1.06 mmol, 71%) as an oil; 1 H NMR δ 1.41 (d, 3H, J = 7, CH 3 ), 2.79 (dd, 1H, J = 16.5 and 11, 13-H ax ), 2.85-3.00 (m, 4H, 5-CH 2 and 6-CH 2 ), 3.06 (dd, 1H, J = 4.5 and 16.5 Hz, 13H eq ), 3.85, 3.87, 3.89 (3s, 12H, 4 x OCH 3 ), 4.11 (q, 1H, J = 7, 8-H eq ), 4.24 (dd, 1H, J = 4.5 and 11, 13a-H), 6.59, 6.60, 6.62, 6.70 (4 x ArH); 13 109.08,109.75,111.11,111.39 (1,4,9,125.26,126.45,130.68,131.78 (4a,8a,12a,174.26 (2,3,11, (14), 79(7), 78(3), 77 (9), 65(4), 55(3), 53(3), 51(4); HRMS exact mass calcd. for C 22 H 27 NO 4 369.1940NO 4 369. , found 369.1922Anal.…”

Section: -Tetramethoxy-6h-dibenzo-[ag]quinolizine [(±)-O-methylcormentioning

confidence: 99%

“…The combined organic extracts were dried with MgSO 4 , filtered, and evaporated. Chromatography of the residue with 50% ethyl acetate in petroleum spirits afforded the title compound 30 as an oil (1.87 g, 7.19 (NCO,rotamers),; m/z: 261(M+2, 26%), 259(M + , 26%), 246(7), 244(7), 215(5), 180(7), 179(27), 164 (9), 126(9), 125(68), 124(8), 111 (11), 110(100), 109 (14), 107 (15), 82(30), 80 (9), 73(24), 55(41). Anal.…”

Section: -(2-bromophenoxycarbonyl)-2-phenyl-23-dihydro-4-pyridone (mentioning

confidence: 99%

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Diastereoselective radical cyclization reactions: the synthesis of O-methylcorytenchirine

Beckwith¹,

Mayadunne²

2004

Arkivoc

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Highly diastereoselective cyclization of radicals such as 4 provides a model for the synthesis of 8-substituted berbines. Thus the reaction of 6,7-dimethoxyisoquinoline 21 with the acid chloride 19 affords the key intermediate 22, which undergoes free radical cyclization on treatment with tributylstannane to give (±)-23 as the sole product. Reduction of 23 affords (±)-Omethylcorytenchirine 14. The carbamate 24 does not undergo radical cyclization when treated with tributylstannane, but the acetyl pyridine 33 affords the cyclized products 37 and 38 in reasonable yield and with good diastereoselectivity.

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Section: Methodsmentioning

confidence: 99%

Section: -Tetramethoxy-6h-dibenzo-[ag]quinolizine [(±)-O-methylcormentioning

confidence: 99%

Section: -(2-bromophenoxycarbonyl)-2-phenyl-23-dihydro-4-pyridone (mentioning

confidence: 99%

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Diastereoselective radical cyclization reactions: the synthesis of O-methylcorytenchirine

Beckwith¹,

Mayadunne²

2004

Arkivoc

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“…We prepared the previously unreported 8-bromo-6,7-dimethoxyisoquinoline 12 from 2-bromo-3,4-dimethoxybenzaldehyde (20,21) via the modified Pomeranz-Fritsch procedure developed by Bewis et al (17). Treatment of isoquinoline 12 with 3,4-dimethoxyphenylmagnesium bromide according to Pridgen's procedure in the presence of "Ni dppp" did not yield the expected 8-phenylisoquinoline.…”

Section: -mentioning

confidence: 99%

Synthesis of indeno[1,2,3-ĳ]isoquinolines

Patel¹,

MacLean²

1983

Can. J. Chem.

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1-Methyl and 1-benzyl-1,2,3,10b-tetrahydro-5,6,8,9-tetramethoxyindeno[1,2,3-ĳ]isoquinoline have been synthesized from the corresponding 8-phenyl-3,4-dihydro-1(2H)isoquinolinones by treatment with POCl3 under Vilsmeier conditions followed by borohydride reduction. The isoquinolinones were prepared in six steps from 2-(2,3,4-trimethoxyphenyl)-4,4-dimethyl-2-oxazoline. This sequence of reactions provides a new route to dihydro and tetrahydroindeno[1,2,3-ĳ]isoquinolines.

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“…[8] Their almost unrestricted availability puts anilines of course in a privileged position as indole precursors. Two classical methods, the Berlinerblau-Nordlander [9][10][11][12][13] and the Bischler-Möhlau [14] route, alkylate the amino function with a side chain containing a protected or unprotected β-oxo group, which enables an acid catalyst to perform an intramolecular Friedel-Crafts hydroxyalkylation. Alternatively one may begin with an ortho-acylation of the aniline.…”

Section: Introductionmentioning

confidence: 99%

In Search of Simplicity and Flexibility: A Rational Access to Twelve Fluoroindolecarboxylic Acids

2006

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All twelve indolecarboxylic acids 1-12 carrying both a fluorine substituent and a carboxy group at the benzo ring have been prepared either directly from the corresponding fluoroindoles 13-16 or from the chlorinated derivatives 22, 23 and 25 by hydrogen/metal permutation ("metalation"), or from the bromo-or iodofluoroindoles 17-20 and 26, 27, 29 and 30 by halogen/metal permutation, the organometallic intermediate being each time trapped with carbon dioxide. In most, though not all cases, the nitrogen atom in the fivemembered ring had to be protected by a trialkylsilyl group. Some of the bromo-or iodofluoroindoles (26 and 27) were successfully subjected to a basicity gradient-driven selective migration of the heavy halogen. An unexpected finding on the way to the target compounds were the rigorously site-

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The synthesis of isoquinolines, indoles and benzthiophen by an improved Pomeranz-Fritsch reaction, using boron trifluoride in trifluoroacetic anhydride

Cited by 48 publications

References 25 publications

Diastereoselective radical cyclization reactions: the synthesis of O-methylcorytenchirine

Diastereoselective radical cyclization reactions: the synthesis of O-methylcorytenchirine

Synthesis of indeno[1,2,3-ĳ]isoquinolines

In Search of Simplicity and Flexibility: A Rational Access to Twelve Fluoroindolecarboxylic Acids

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