Synthesis and spectroscopic studies on the base-stabilized aryloxyboron derivatives BX2{2-(NMe2CH2)OC6H4}, BX2{2-(NEt2CH2)OC6H4} and BX2{2,6-(NEt2CH2)(2)OC6H3}, (X = Cl, Et, H) and molecular structures of BCl2{2-(NEt2CH2)(2)OC6H4} and [BCl2{2-NHEt2CH

摘要

1-HO-2-(NMe2CH2)C6H4 (1a), 1-HO-2-(NEt2CH2)C6H4 (1b) and 1-HO-2,6-(NEt2CH2)(2)C6H3 (1c) reacted with BuLi to give the lithium salts 1-LiO-2-(NMe2CH2)C6H4 (2a) and 1-LiO-2,6-(NEt2CH2)(2)C6H3 (2c) or the phenol adducts [{1-LiO-2- (NR2CH2)C6H4}(2){1-HO-2-(NR2CH2)C6H4}] (R = Me (3a), Et (3b)). The phenol derivatives 1a-c reacted with BEt3 or BH3. thf with elimination of EtH or H-2 to give BX2 {2-(NMe2CH2)OC6H4} (X = Et (4a). H (5a)), BX2 {2-(NEt2CH2)OC6H4} (X = Et (4b), H (5b)) and BX2(2,6-(NEt2CH2)(2)OC6H3} (X=Et (4c), H (5c)). The reaction of 2a and 3b with BCl3 in toluene yielded BCl2 {2-(NMe2CH2)OC6H4} (6a) and BCl2{2-(NEt2CH2)OC6H4) (6b), while 2c afforded a mixture of BCl2{2,6-(NEt2CH2)(2)OC6H3} (6c) and BCl2{2-N(BCl3)Et2CH2-6-(NEt2CH2)OC6H3} (6c . BCl3). Treatment of this mixture with [PPh4]Cl gave [BCl2{2-NHEt2CH2-6-(NEt2CH2)OC6H3}]Cl (6c . HCl). The HCl-free product 6c was obtained from 6c . HCl and NaH. Compounds 2-6 and 6c . HCl were characterized spectroscopically (NMRI, IR), 5a and 6a-c also by MS, and crystal structures were determined for 6b and 6c . HCl. The borane derivatives 4-6 exhibit dynamic behavior in solution (ring opening and ring inversion), which was studied by VT H-1 NMR spectroscopy. (C) 2001 Elsevier Science Ltd. All rights reserved. [References: 68]