3-AMINO-4,5,6,7-TETRAHYDRO-BENZO[B]THIOPHENE-2-CARBOXYLIC ACID METHYL ESTER synthesis

Yield:119205-38-8 80%

Reaction Conditions:

with potassium tert-butylate in tetrahydrofuran; for 0.5 h;Reflux;Inert atmosphere;

Steps:

Methyl-3-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxylate (1)

Methyl-S-(2-cyanocyclohex-1-enyl)sulphanylacetate (9) (0.17 g, 0.78 mmol) was mixed with freshly distilled dry THF (3 mL). Potassium t-butoxide (0.09 g, 0.78 mmol) was added and the solution was heated at reflux for 30 minutes. The reaction was monitored by TLC (eluent: PE/EtOAc 5:1). The mixture was concentrated under vacuum, CH₂Cl₂ (25 mL) was added and the solution was washed by distilled water (2x20 mL) and dried over MgSO₄. The solvent was evaporated and the obtained oil was dried under high vacuum (10^-1 mbar). The yellowish solid was obtained after refrigerating overnight (135 mg, 80 %). Mp 70-73 °C; δ_H (CDCl₃): 1.82 (m, 4H, H5 a H6), 2.30 (m, 2H, H7), 2.67 (m, 2H, H4), 3.79 (s, 3H, COOCH₃), 5.36 (brs, 2H, NH₂); δ_C (CDCl₃): 21.9 and 22.6 (2CH₂ - C5 and C6), 23.1 (CH₂ - C4), 25.8 (CH₂ - C7), 51.1 (COOCH₃), 97.3 (C_Ar), 126.2 (C_Ar), 143.5 (C_Ar), 152.6 (C_Ar), 165.4 (COOCH₃); IR (KBr): 768, 1072, 1095, 1130, 1198, 1263, 1300, 1342, 1448, 1493, 1568, 1604, 1668, 1734 (ester), 2858, 2933, 3361 (NH₂), 3464 (NH₂); MS (EI, 70 eV): m/z (%) = 32 (80), 40 (10), 45 (10), 65 (10), 77 (15), 91 (15), 118 (15), 151 (65), 179 (90), 211 (M⁺, 100), 212 (M+H⁺, 10); HRMS-FAB: m/z [M+H]⁺ calcd for C₁₀H₁₃NO₂S: 211.0667; found: 211.0745.

References:

Tenora, Luká?;Buchlovi?, Marian;Man, Stanislav;Potá?ek, Milan [Tetrahedron Letters,2011,vol. 52,# 3,p. 401 - 403] Location in patent:supporting information; experimental part