TiCl₄/Et₃N-Mediated Condensation of Acetate and Formate Esters: Direct Access to β-Alkoxy- and β-Aryloxyacrylates

Abstract

A methodology to build (E)-β-alkoxy- and (E)-β-aryloxyacrylate moieties from acetate and formate esters promoted by the TiCl/EtN system is presented. The reaction is compatible with a broad range of structural skeletons and elapses through an unusual condensation pathway. Taking into account the obtained results, we propose a plausible mechanism involving a bimetallic titanium intermediate for this type of transformation.

Selective C–H bond electro-oxidation of benzylic acetates and alcohols to benzaldehydes

“…Preparation of benzyl acetates. 22 A round bottom flask equipped with a magnetic stirrer was charged with the appropriate benzyl alcohol (10.0 mmol) and acetic anhydride (15.0 mmol). The reaction mixture was refluxed (85°C) for 15 h. Upon cooling to room temperature the reaction mixture was poured into water (50 mL).…”

Catalyst-Controlled Selective Functionalization of Unactivated C–H Bonds in the Presence of Electronically Activated C–H Bonds

“…8, 140.7, 135.8, 132.0, 131.5, 130.3, 130.2, 122.9 (q, J = 277.3 Hz), 122.0, 119. 7,60.5 (q,J = 36.6 Hz)., 57.6, 35.8, 35.0, 32.2, 17.7; 19 F NMR (282 MHz, CDCl3) δ -73.7 (t, J = 8.5 Hz); IR (neat) 2932,1749,1488,1130,1072,1011,826,801,760, 717 cm -1 ; HRMS (+p NSI) calcd for C20H20O2Br2F3 (M+H) + 506.9777 found 506.97899; HPLC (the ester product was reduced to 2,5-bis(4-bromophenyl)-3-methylpentan-1-ol for better separation) (ODH column, 6% i-propanol in hexane, 0.25 mL min -1 , 1 mg mL 70 min,UV 230 nm) retention times of 43.05 min (major) and 50.56 min (minor) 92% ee with Rh2(S-2-Cl-5-BrTPCP)4.…”

“…Ueq F1 3107.8 7-1535 33482.8 (6) 40.3 (4) F22927.5 7-699 44163.9 743.1 (5) F33029. 6(8) 2168 33682.3 744.3 (5) F46931.1 (8) 10422 (4) 11116.2 (8) 54.0(5) F5 6790.1 (7) 13309 (3) 11567.5 (6) 34.1(4) F6 7051.5 (9) 14083 (5) 10937. 5(8) 63.2(7) O1 4027.…”

“…Rf = 0.64 (pentane/diethyl ether = 9/1); [α] 20 D: +25.3° (c = 1.04, CHCl3, 93% ee); 1 H NMR (600 MHz, CDCl3) δ 7.58 (d, J = 8.1 Hz, 2H), 7.41 (d, J = 8.0 Hz, 2H), 7.33 (d, J = 8.3 Hz, 2H), 6.91 (d, J = 8.3 Hz, 2H), 4.55 (dq, J = 12.7, 8.4 Hz, 1H), 4.33 (dq, J = 12.7, 8.4 Hz, 1H), 3.43 (d, J = 10.5 Hz, 1H), 2.49 -2.43 (m, 1H), 2.37 -2.30 (m, 1H), 2.29 -2.19 (m, 1H), 1.64 -1.55 (m, 1H), 1.49 -1.41 (m, 1H), 1.19 -1.12 (m, 1H), 1.03 (d, J = 6.5 Hz, 3H), 0.99 -0.91 (m, 1H). ;13 C NMR (151 MHz, CDCl3) δ 171 7,. 141.1, 141.0, 131.4, 130.1, 129.1, 125.8 (q, J = 3.7 Hz), 124.1…”

“…m.p. 141-143 o C Rf = 0.45 (pentane/diethyl ether = 9/1); [α] 20 D: -11.0 ° (c = 1.00, CHCl3, 5.6:1 d.r., >99% ee); 1 H NMR (600 MHz, CDCl3) δ 7.16 (d, J = 8.0 Hz, 4H), 7.01 (d, J = 8.1 Hz, 4H), 4.55 (dq, J = 12.7, 8.5 Hz, 2H), 4.27 (dq, J = 12.7, 8.4 Hz, 2H), 3.21 (d, J = 11.4 Hz, 2H), 2.58 (dt, J = 13.1, 6.4 Hz, 2H), 2.42 (dt, J = 13.6, 7.6 Hz, 2H), 2.19 -2.09 (m, 2H), 1.48 -1.27 (m, 6H), 1.12 -0.96 (m, 10H), 0.96 -0.85 (m, 4H), 0.80 -0.68 (m, 2H);13 C NMR (151 MHz, CDCl3) δ 172 7,. 141.8, 134.4, 128.8, 128.2, 122.95 (q, J = 277.3 Hz), 60.21 (q, J = 36.5 Hz), 58.…”