4,8-Dimethyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,3,6,2-dioxazaborocane

Abstract

[1175712-33-0, 1177425-14-7, 1262977-13-8, 1303527-12-9] C12H25B2NO4 (MW 268.95) InChI = S/C12H25B2NO4/c1-9-7-15-8-10(2)17-13(16-9)14-18-11(3,4)12(5,6)19-14/h9-10,15H,7-8H2,1-6H3 InChIKey = IGLQSAGCEMHFPH-UHFFFAOYSA-N (reagent used as a boron source, in conjunction with a copper catalyst, to install a pinacol boronic ester onto electron-deficient alkenes and alkynes) Alternate Names: pinacolatodiisopropanolaminatodiboron; PDIPA diboron. Physical Data: decomposes before melting point is reached. Solubility: dichloromethane, acetonitrile, acetone, DMF, DMSO. Partially soluble in most nonpolar aprotic organic solvents, for example, THF and ethyl acetate. Form Supplied in: fluffy white solid. Analysis of Reagent Purity: purity is analyzed by 1H NMR (500 MHz, CD3CN) δ = 5.45 (s, br, 1H, cis), 5.18 (s, br, 1H, trans), 4.13–4.04 (m, 2H, cis; 1H, trans), 3.70–3.63 (m, 1H, trans), 3.32–3.27 (m, 1H, trans), 2.83 (dd, J = 11.7, 4.5 Hz, 2H, cis), 2.69 (dd, J = 11.5, 3.7 Hz, 1H, trans), 2.51–2.45 (m, 2H, cis), 2.27–2.22 (m, 1H, trans), 1.92–1.86 (m, 1H, trans), 1.15 (s, 12H, cis; 12H, trans), 1.13 (d, J = 6.2 Hz, 3H, trans), 1.12 (d, J = 6.2 Hz, 3H, trans), 1.07 (d, J = 6.0 Hz, 6H, cis); 13C NMR (125 MHz, CD3CN) δ = 81.40 (cis), 81.29 (trans), 70.68 (cis), 67.47 (trans), 66.82 (trans), 57.96 (trans), 57.82 (cis), 56.44 (trans), 24.71 (trans), 24.69 (trans), 24.65 (cis), 20.36 (cis), 19.04 (trans), 18.32 (trans); 11B NMR (160 MHz, CD3CN) δ = 35.51 (sp2-B), 8.95 (sp3-B); IR (NaCl) 3074, 2972, 2928, 2883, 1369, 1250, 1115, 1022, 970, 854, 806 cm−1; HRMS (ESI+): Calcd for C12H26B2NO4 [M+H]+: 270.2048, Found: 270.2046; Calcd for C12H25B2NNaO4 [M+Na]+: 292.1867, Found: 292.1865; Elemental analysis: Calcd for C12H25B2NO4: C, 53.59; H, 9.37; N, 5.21; Found: C, 53.69; H, 9.41; N, 5.14. Preparative Methods: the diboron reagent is readily prepared from commercially available bis(pinacolato)diboron and bis(2-hydroxypropyl)amine in 8:1 CH2Cl2/ether.1 The product precipitates and is isolated as a mixture of diastereomers. This material as a borylating agent is as effective as the enantiopure version. Purification: the white solid is filtered and washed with copious amounts of diethyl ether. Residual ether is removed under high vacuum. Handling, Storage, and Precautions: to help prevent autoxidation, store under nitrogen and refrigerate. Incompatible with strong acids, strong bases, and oxidizing agents. Rapidly hydrolyzes in water and alcoholic solvents and during TLC analysis.