Recent developments in the chemistry of amine- and phosphine-boranes

Synthesis of Racemic and Enantiomerically Pure (R*,R*,R*)‐Tris(α‐methylbenzyl)phosphane − X‐ray Crystal Structures of the Phosphane Oxides and Borane Complexes

“…[32] The organic layer was extracted with Et 2 O (3 ϫ 50 mL), dried (MgSO 4 ) and the solvents evaporated to dryness under reduced pressure yielding a partially solid yellow oil. This crude mixture was purified using flash chromatography, eluting with petroleum ether-EtOAc 20:1, to give a 3:4 mixture of (RS,RS,RS)-tris(α-methylbenzyl)phosphaneϪborane (7) (RS,RS,RS)-Tris(α-methylbenzyl)phosphane (1): (RS,RS,RS)-Tris-(α-methylbenzyl)phosphaneϪborane (7, 50.0 mg, 0.139 mmol) was dissolved in freshly distilled anhydrous diethylamine (1 mL, 9.65 mmol) and heated at reflux (65°C) under N 2 for 2 h. [16,33] The mixture was cooled to room temperature and de-oxygenated HCl (5 mL of an aqueous 2  solution) was added cautiously, followed by de-oxygenated Et 2 O (5 mL). The mixture was stirred vigorously for 5 min to ensure complete extraction of the organics and the aqueous layer was then decanted using a pipette.…”

Chemistry of α‐Aminoboronic Acids and their Derivatives

“…Attempts to obtain the (R)-1,4-diaminobutane-1-boronic acid (108) from (105) and (106) were unsuccessful. The N-protective group in (104) could be desilylated when treated with benzyl chloroformate to give the monoprotected boroornithine derivative (107), which should be a valuable precursor of the arginine boronic acid analogs. Peptides containing C-terminal boronic acid derivatives of ornithine, lysine, arginine, or homoarginine and corresponding isothiuronium analogs are reversible inhibitors of trypsin-like serine proteases such as thrombin, plasma kallikrein, and plasmin, and are useful in treatment of blood coagulation disorders and inflammation [77].…”

“…This resemblance has inspired extensive biological screening of these molecules, and the promising early results led to the syntheses of a large number of ester [96][97][98][99], amide [100,101], peptide [102,103], hydroxamic acid [104], and transition metal [105][106][107] derivatives of amine-carboxyboranes (A-BH 2 COX, X ¼ OR, NR 1 R 2 , or NHOH) containing a broad range substitutes, among other amine-boranes, which have been reviewed recently [2,108,109].…”

Computational study of the fluorination effect on nitrogen–boron bond

“…A typical property of electron-deficient boranes is their Lewis acidity, which reflects the fact that boron possesses fewer valence electrons than valence orbitals. As a result, boron hydride BH 3 and its halides BX 3 readily form donor-acceptor complexes with Lewis bases such as NH 3 and N(CH 3 ) 3 [1][2][3][4][5].…”