Abstract
2-Isopropoxy-4H-1,3,2-benzodioxaborin(I), obtained from isopropyl borate and o-hydroxybenzyl alcohol, reacts with a variety of hydroxy compounds (viz., t-butyl alcohol, phenol, ethane- 1,2-diol, 2-aminoethanol, o-amino phenol) and acetic anhydride to give the corresponding 2-substituted heterocycles. Reactions of (I) as well as other 1,3-dioxa-2-bora heterocycles with bases (viz., ammonia, triethylamine, pyridine, dimethylformamide) show that the electrophilicity of boron decreases in the order: 2-alkoxy-1,3,2-benzodioxaborole>2-phenoxy-4H-1,3,2-benzodioxaborin>(I)>2-alkoxy-1,3,2-dioxaborinane. Codisproportionation reaction between bis(4H-1,3,2-benzodioxaborin-2-yl)oxide (obtained directly from boric acid and o-hydroxybenzyl alcohol) and triorganotin hydroxide or oxide yields 2-triorganostannoxy-4H-1,3,2-benzo-dioxyborin. Cleavage and insertion reactions of these compounds have been studied.