Synthesis and Properties of 2-(Dimesitylboryl)benzylideneamines

Abstract

Lithiation of 2-(2-bromophenyl)-dioxolane (1) followed by reaction with dimesitylboron fluoride afforded 2-(2-dimesitylborylphenyl)-dioxolane (2) which was deprotected to afford 2-dimesitylboryl-benzaldehyde (3). Compound 3 reacts with aliphatic amines such as n-butylamine and ethanolamine to afford the corresponding imines 2-(dimesitylboryl)benzylidenebutylamine (4) and 2-(dimesitylboryl)benzylideneethanolamine (5), respectively. Structural studies indicate coordination of the imine-nitrogen atom to the boron center. Imines 4 and 5 emit a green fluorescence near 510 nm with quantum yields approaching 10 %. TD-DFT calculations suggest that this emission arises from an intramolecular charge-transfer excited state.

Direct and Base-Catalyzed Diboration of Alkynes Using the Unsymmetrical Diborane(4), pinB-BMes2

“…The major isomer ( 11a ) was structurally characterized by single-crystal X-ray diffraction analysis (Figure ). The intramolecular Mes 2 B–N coordination bond [1.717(3) Å] in 11a was slightly longer than that of a similar B–N coordination bond in a three-carbon-containing five-membered ring, ,,,,,, probably due to the ring strain of the fused tricyclic system in 11a . A similar structural characterization of 11d by X-ray diffraction analysis was prevented by the isomerization of 11d to 11a upon recrystallization.…”

A simple multi-responsive system based on aldehyde functionalized amino-boranes

“…Analytical thin-layer chromatography was performed on glass plates of Silica Gel GF-254. Compounds BN 10 a and BO 14 were prepared using methods described in the literature. 5-( N , N -Dimethylamino)-2-bromobenzaldehyde ( 1a ) was also prepared according to a literature procedure.…”

“…In addition, an aldehyde group was chosen as the donor for binding to boron because it is a relatively weak donor, as indicated by the 11 B chemical shift of the previously reported compound BO at 25 ppm (compared to the corresponding imine analogue that has a 11 B chemical shift of 5 ppm). 14 The second feature is the installation of an NMe 2 donor unit, which is well known to produce strong intramolecular charge transfer (ICT) transitions when combined with a triarylboron. 9 , 10 Furthermore, the amino group allows the modulation of the electron density/electrophilicity of the boron centre.…”

Structural Dynamics and Stereoselectivity of Chiral Benzylideneamine N,C‐Chelate Borane Photo–Thermal Isomerization

“…Chiral B(bza‐R)Mes 2 compounds were synthesized and isolated as mixtures of the major diastereomer and the minor diastereomer, 1S + 1S′ , 1R + 1R′ , 1S‐Me + 1S‐Me′ , and 1R‐Me + 1R‐Me′ , respectively, in good yields, using a modified literature procedure, as shown in Scheme . Within the 1S + 1S′ mixture, 1S is the major diastereomer, whereas 1S′ is the minor diastereomer.…”

“…First, the precursor 1‐(2‐(dimesitylboraneyl)phenyl)ethan‐1‐one was prepared according to a modified literature procedure (see Supporting Information). Compound 1S‐Me + 1S‐Me′ was prepared by using a modified literature procedure in which 1‐(2‐(dimesitylboraneyl)phenyl)ethan‐1‐one (0.13 mmol) and ( S )‐1‐phenylethan‐1‐amine (2 m in THF, 0.15 mL, 0.3 mmol) were dissolved in dichloromethane with an excess amount of magnesium sulfate, and the reaction mixture was heated to 50 °C for 1.5 h . After reaction completion was confirmed by TLC (1:1 CH 2 Cl 2 /hexane), the crude product was purified by using column chromatography on neutral alumina gel (1:2 CH 2 Cl 2 /hexane) to afford 1S‐Me + 1S‐Me′ as a yellow solid, in a ratio of 6:1 (50 % yield).…”