Borheterocyclen, 1. Mitt.

Waste‐Free and Facile Solid‐State Protection of Diamines, Anthranilic Acid, Diols, and Polyols with Phenylboronic Acid

“…217 ± 220 8C) are co-ground in a mortar at room temperature and heated to 40 8C in a vacuum for 1 h. Alternatively the mixture of reagents can be melted at 100 ± 110 8C in a vacuum, while the water of reaction is removed by evaporation from the hot melt (Scheme 1). This reaction is superior to the corresponding solution reaction, which gave a 79 % [3] or 92 % [4] yield and required purifying workup. The deprotection of 3 has been described, [5] and it can also be quantitatively performed in boiling aqueous Na 2 CO 3 .…”

“…If they are present in 1,2-or in favorable 1,3-positions, cyclic amides or esters may be formed for that purpose. The synthesis of some 1,3,2-dioxaborolanes/-dioxaborinines, [2] and 1,3,2-diazaborolanes/-diazaborinines [3] (five-and six-membered heterocyclic aryl boronic acid esters and amides) has been described. These cyclization reactions of 1,2-diamines and 1,2-diols were performed in solution or at functionalized polymer surfaces with yields ranging from 21 to 97 %.…”

“…The same product 7 was obtained in a solution reaction, however, in only 90 % yield. [3] Scheme 3. Quantitative solid-state synthesis of 7 in a ball-mill.…”

“…224 À 226 8C; ref. [3]: 228 8C. Complete deprotection was achieved by boiling 7 (200 mg) in 5 % NaHCO 3 solution (20 mL) for 1 h.…”

Solution-state 15N NMR and solid-state single-crystal XRD study of heterosubstituted diazaboroles and borinines prepared via an effective and simple microwave-assisted solvent-free synthesis

“…Literature had presented a possible method which makes use of commercially available boronic acids and simple 1,2-diols or diamines to create a wide range of dioxo-or diazaboroles and borinines (Scheme 3) [6,7]. However, these reactions make use of hazardous solvents such as benzene and toluene, and therefore, in an attempt to find a "greener" method, a solventless approach was desired.…”