Borates and Boronates from Bidentate Ligands

While 1,2- and 1,3-alkanediols form only monomeric 1,3,2-dioxaborolanes and 1,3,2-dioxaborinanes with triethylborane, 1,4- and 1,5-alkanediols give mainly dimeric macrocyclic boronates 41 and 42, which are obtained in yields of 70-75% after purification by vacuum distillation. As lateral products oligo-and polymeric molecules are formed. The main products have a 14- and 16-membered heterocyclic ring, respectively (Fig. 15) [84]. 

Dimeric diboronates 43 and 44 are obtained if the dithioboronic ester RB(SBu)2 (R = nBu, Ph) is heated with bisphenol H0C6H4CMe2C6H40H (Fig. 15) [86]. 

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