New Procedures for the Synthesis of Symmetrical Bisbenzylated Ureas Based on N-Benzyltrichloroacetamides

Atom Transfer Radical Cyclization of Trichloroacetamides to Electron-Rich Acceptors Using Grubbs’ Catalysts: Synthesis of the Tricyclic Framework of FR901483

“…Method C : To a suspension of CuCl (17.5 mg, 0.18 mmol, 30%) in acetonitrile (2 mL) was added 1a (200 mg, 0.59 mmol), and the mixture was heated at 80 °C overnight in a sealed tube. The solution was then allowed to reach rt, concentrated, and purified by chromatography (hexane/CH 2 Cl 2 1:1 to CH 2 Cl 2 ) to yield 2a (104 mg, 61%) and secondary amide 1g as a solid (58 mg, 35%). For 1g (see Table ): IR (film) 3316, 3044, 3002, 2955, 2838, 1693, 1659, 1615, 1583 cm –1 ; 1 H NMR (CDCl 3 , 400 MHz) δ 3.81 (s, 3H), 4.48 (s, 2H), 6.90 (dm, J = 8.6 Hz, 2H), 7.24 (dm, J = 8.6 Hz, 2H); 13 C NMR (CDCl 3 , 100 MHz) δ 44.9 (CH 2 ), 55.3 (CH 3 ), 92.6 (CCl 3 ), 114.3, 129.2, 128.3, 159.5, 161.7 (NCO).…”

Urea Derivatives from Pentadiplandra brazzeana

“…N , N ‘ -Di-(4-methoxybenzyl)urea (2) : white crystals (hexane−EtOAc); mp 171−173 °C (lit . 170−172 °C); IR (KBr) ν max 3325, 2920, 1615, 1580, 1510, 1250, 1175, 1030, 810 cm -1 ; 1 H NMR (CDCl 3 , 500 MHz) δ 3.69 (6H, s, 2 × OMe), 4.17 (4H, s, H-2,-2‘), 6.75 (4H, d, J = 8.5 Hz, H-5,-5‘,-7,-7‘), 7.09 (4H, d, J = 8.5 Hz, H-4,-4‘,-8,-8‘); 13 C NMR (CDCl 3 , 125 MHz) δ 158.6 (C-1,-6,-6‘), 131.3 (C-3,-3‘), 128.4 (C-4,-4‘,-8,-8‘), 113.8 (C-5,-5‘,-7,-7‘), 56.9 (C-2,-2‘), 55.1 (2 × OMe); EIMS (70 eV) m / z [M] + 300 (25), 271 (17), 270 (14), 192 (4), 180 (44), 136 (100), 121 (89), 106 (15), 91 (18), 77 (14), 51 (3); anal .…”

“…Compounds 2 , 3 , and 4 were identified as N , N ‘-di-(4-methoxybenzyl)urea, N , N ‘-dibenzylurea, and p -methoxythiobenzaldehyde from their physical and spectroscopic data. These three compounds have previously been prepared by synthesis and are reported herein from nature for the first time. − …”

“…These three compounds have previously been prepared by synthesis and are reported herein from nature for the first time. [6][7][8]…”

“…crystals (hexane-EtOAc); mp 171-173 °C (lit 6. 170-172 °C); IR (KBr) νmax 3325, 2920, 1615, 1580, 1510, 1250, 1175, 1030, 810 cm -1 ; 1 H NMR (CDCl3, 500 MHz) δ 3.69 (6H, s, 2 × OMe), 4.17 (4H, s, H-2,-2′), 6.75 (4H, d, J ) 8.5 Hz, H-5,-5′,-7,-7′), 7.09 (4H, d, J ) 8.5 Hz, H-4,-4′,-8,-8′); 13 C NMR (CDCl3, 125 MHz) δ 158.6 (C-1,-6,-6′), 131.3 (C-3,-3′), 128.4 (C-4,-4′,-8,-8′), 113.8 (C-5,-5′,-7,-7′), 56.9 (C-2,-2′), 55 1.…”