13061-96-6Relevant articles and documents
Synthesis of Boroxine and Dioxaborole Covalent Organic Frameworks via Transesterification and Metathesis of Pinacol Boronates
Hamzehpoor, Ehsan,Jonderian, Antranik,McCalla, Eric,Perepichka, Dmitrii F.
supporting information, p. 13274 - 13280 (2021/09/07)
Boroxine and dioxaborole are the first and some of the most studied synthons of covalent organic frameworks (COFs). Despite their wide application in the design of functional COFs over the last 15 years, their synthesis still relies on the original Yaghi's condensation of boronic acids (with itself or with polyfunctional catechols), some of which are difficult to prepare, poorly soluble, or unstable in the presence of water. Here, we propose a new synthetic approach to boroxine COFs (on the basis of the transesterification of pinacol aryl boronates (aryl-Bpins) with methyl boronic acid (MBA) and dioxaborole COFs (through the metathesis of pinacol boronates with MBA-protected catechols). The aryl-Bpin and MBA-protected catechols are easy to purify, highly soluble, and bench-stable. Furthermore, the kinetic analysis of the two model reactions reveals high reversibility (Keq ～1) and facile control over the equilibrium. Unlike the conventional condensation, which forms water as a byproduct, the byproduct of the metathesis (MBA pinacolate) allows for easy kinetic measurements of the COF formation by conventional 1H NMR. We show the generality of this approach by the synthesis of seven known boroxine/dioxaborole COFs whose crystallinity is better or equal to those reported by conventional condensation. We also apply metathesis polymerization to obtain two new COFs, Py4THB and B2HHTP, whose synthesis was previously precluded by the insolubility and hydrolytic instability, respectively, of the boronic acid precursors.
FUNCTIONALIZED PRIMARY ALKYLTRIFLUOROBORATE SALTS AND METHOD FOR MAKING THE SAME
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Paragraph 0100-0102, (2017/03/21)
The invention provides methods for preparing boronic acids, for example, primary alkyl or alkenyl boronic acids, and alkali metal alkyl trifluoro borate salts, as described herein, wherein the primary alkyl boronic acids and the potassium alkyl trifluoroborate salts can contain one or more unprotected functional groups.
Isolation and characterization of borane complexes of dimethylsulfoxonium methylide
Stoddard,Shea
, p. 1124 - 1131 (2008/10/08)
Trialkylboranes (R3B) catalyze the repetitive insertion of methylene from dimethylsul-foxonium methylide (1) to form polymethylene. A proposed intermediate in this reaction is a 1:1 complex between R3B and ylide 1. Following complexation, an alkyl group (boron-substituted) undergoes a 1,2-migration to the methylide carbon with displacement of a molecule of DMSO. A series of complexes of dimethylsulfoxonium methylide (1) and various organoboranes, X3B (X = H, Ph, F, C6F5), have been prepared and isolated. Molecular structures, obtained by single-crystal X-ray diffraction, for ylide·BF3 (3) and ylide·B(C6F5)3 (4) were found to contain geometries with potential migrating groups anti-periplanar to the carbon-sulfur bond. The stability of solutions of these complexes ranges considerably. For example, ylide·BPh3 (6) undergoes reaction at room temperature, while ylide·B(C6F5)3 (3) is stable to temperatures > 100 °C. All complexes can be prepared as solids stable at room temperature. The solid-state stability of ylide·BR3 complexes was evaluated by differential scanning calorimetry. The decomposition temperature increases across the series for R = H, Ph, C6F5, F. The heats of reaction of ylide·BR3 are R = H (-54.7), Ph (-15.7), C6F5 (-21.6), and F (-17.1) kcal mol-1, respectively.
Organoboranes. 39. Convenient procedures for the preparation of methylboronic acid and trimethylboroxin
Brown, Herbert C.,Cole, Thomas E.
, p. 816 - 821 (2008/10/08)
Methylboronic acid and its anhydride, trimethylboroxin, were prepared by three routes. The carbonylation of borane-dimethyl sulfide gives in high yields trimethylboroxin, readily hydrated to methylboronic acid. The reaction of methyllithium with selected
