ChemicalBook CAS DataBase List Tadalafil Impurity 20

Tadalafil Impurity 20 synthesis

3synthesis methods

Product Name:Tadalafil Impurity 20
CAS Number:406938-39-4
Molecular formula:C19H16N2O4
Molecular Weight:336.34

(1R,3R)-METHYL-1,2,3,4-TETRAHYDRO-1-(3,4-METHYLENEDIOXYPHENYL)-9H-PYRIDO[3,4-B]INDOLE-3-CARBOXYLATE

171596-41-1
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406938-39-4
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Yield:406938-39-4 100%

Reaction Conditions:

Stage #1: (1R,3R)-methyl 1,2,3,4-tetrahydro-1-(3,4-methylenedioxyphenyl)-9H-pyrido[3,4-b]indole-3-carboxylatewith lithium hydroxide;water in tetrahydrofuran at 0 - 20;
Stage #2: with hydrogenchloride in tetrahydrofuran;water;

Steps:

1

A suspension of Intermediate 1 (4.11 g, 10.6 mmol) in tetrahydrofuran (10 mL) and water (10 mL) was cooled to 0° C. To this mixture was added lithium hydroxide monohydrate (1.04 g, 24.8 mmol), and the resulting mixture warmed slowly to room temperature overnight. The mixture then was neutralized to pH 7 with hydrogen chloride (1 M in ether), followed by extraction with methylene chloride (2×100 mL). The combined organic extracts were dried over Na2SO4, filtered, then concentrated to provide Intermediate 2 as an off-white powder (3.55 g, 100%): 1H NMR (300 MHz, DMSO-d6): δ 10.32 (s, 1H), 7.41 (d, J=6.2 Hz, 1H), 7.22 (d, J=6.2 Hz, 1H), 7.05-6.87 (m, 5H), 6.01 (s, 2H), 5.25 (s, 1H), 3.57-3.52 (m, 1H), 3.09-3.07 (m, 1H), 2.80-2.70 (m, 1H).

References:

US2003/207906,2003,A1 Location in patent:Page/Page column 11; 12

59259-90-4 Synthesis