1,3,2‐Diselenaborolanes with an Annelated Dicarba‐closo‐dodecaborane(12) Unit: Synthesis, Molecular Structure and Reactivity

Abstract

Keywords: Main group elements / Carboranes / Boron / Selenium / Heterocycles / Density functional calculations / Multinuclear NMR spectroscopy Exchange reactions of 2,2-dimethyl-1,3-diselena-2-silacyclopentane and 2,2,3,3-tetramethyl-1,4-diselena-2,3-disilacyclohexane, as the 4,5-and 5,6-[1,2-dicarba-closo-dodecaborano(12)] derivatives, respectively, with boron trihalides (BCl 3 , BBr 3 , BI 3 ) and dichlorides (PhBCl 2 , iPr 2 NBCl 2 ) afford the corresponding 1,3,2-diselenaborolanes in essentially quantitative yield. The products were characterized in solution by multinuclear magnetic resonance spectroscopy ( 1 H,

Selective Consecutive Insertion of Alkynes into the B–Se Bonds of 1,3,2‐Diselenaborolane Derivatives: Synthesis and Molecular Structures of Nine‐Membered Rings

“…[7] Dried [D 8 ]toluene was saturated with acetylene (1 atm) at 0°C. Carefully dried solvents and oven-dried glassware were used throughout.…”

“…The starting materials, that is, 2a-e, were prepared as described previously. [7] ] was cooled to -50°C, and tert-butylethyne (0.032 mL, 21 mg, 0.26 mmol) was added through a microsyringe. Other starting materials were purchased from Aldrich [hex-3-yne (99 %), 3,3-dimethylbut-1-yne (98 %), 1-phenylbut-1-yne (99 %), 1,4-dichlorobut-2-yne (99 %), phenylethyne (98 %), dimethyl acetylenedicarboxylate (99 %)], and used as received.…”

“…[7] Dried [D 8 ]toluene was saturated with acetylene (1 atm) at 0°C. 1 [7] ] was cooled to -50°C, and hex-3-yne (0.027 mL, 19.5 mg, 0.24 mmol) was added through a microsyringe. NMR measurements: Bruker DRX 500 and Bruker ARX 250: 1 H, 10 10 B NMR spectra were recorded to observe the extremely broad 10 B NMR signals of diluted samples.…”

“…Reactions of the 1,3,2-diselenaborolanes 2a with two terminal alkynes. The 77 Se NMR spectra [11] of the reaction solutions are particularly instructive, because compounds of type 4 give rise to two signals, one broad [7] (B-Se-C) and one sharp (C-Se-C; see Figure 1B or Figure 2). 13 C, 11 B and 77 Se NMR spectroscopic data [a] for the ortho-carborane derivatives 4a, 5a-d and 7a in [D 8 step.…”

“…[1,2] Although some applications of noncyclic selenoboranes [1,2] have been described, [3] their cyclic analogues appear to be even more intriguing due to their potential use in heterocyclic synthesis [4,5] or as ligands for transition-metal complexes. [5b,5c] Recently, we prepared the first stable 1,3,2-diselenaborolane derivatives 2 (Scheme 1) [7] starting from the silane 1 [8] through exchange reactions. [5b,5c] Recently, we prepared the first stable 1,3,2-diselenaborolane derivatives 2 (Scheme 1) [7] starting from the silane 1 [8] through exchange reactions.…”