Boron Analogs of Valine, Leucine, and Isoleucine: Synthesis of Amine-Alkyl(C-alkoxycarbonyl)boranes and Amine-Alkyl(N,N-diethylcarbamoyl)boranes

Synthesis of Amine-dicyanohydroboranes, [Amine-bis(ethylnitrilium)hydroboron(2+)] Tetrafluoroborates, and Their Derivatives as Precursors of Amine-dicarboxyboranes

“…Sutton et al have put considerable effort into the synthesis of amine-alkyl(carboxy)boranes via e.g. [amine-alkyl( C -alkoxy- N -ethylnitrilium)hydroboron(1+)] cations, but their attempts remained unsuccessful, similarly to those of Spielvogel et al, due to the presence of electron-donating alkyl group on the boron, which caused an increase in the hydridic character of the hydrogen attached to boron. Such compounds decomposed in acidic media instead of hydrolyzing into the corresponding carboxyborane complexes.…”

“…These investigations revealed anticancer, − antiosteoporotic, antiinflammatory, ,, and hypolipidemic ,, properties, and these molecules have also been mentioned as possible boron carriers to tumor cells for boron neutron capture therapy . Initiated by these biological properties numerous derivatives of amine carboxyboranes have been prepared, nevertheless, attempts aimed at the synthesis of derivatives substituted on the boron resulted in only a limited number of new molecules. − …”

Synthesis and examination of amine-cyanocarboxyboranes, the boron analogues of α-cyanocarboxylic acids: X-ray structural study of the first lactam containing a boron atom in the lactam ring

“…However, only a limited number of amine-carboxyboranes containing an additional substituent on the boron atom [A AE BH(Y)COX] have been synthesized so far [17]. Lately several new derivatives of amine-cyanoboranes and amine-carboxyboranes containing substituents on the boron atom have been prepared in our laboratory, such as amine-bromocyanoboranes (A AE BH(Br)-CN), amine-dibromocyanoboranes (A AE BBr 2 CN), salts of boronium ions having the composition of [AA 0 B(H)-CN] + [18,19], amine-bromocarboxyboranes (A AE BH(Br)-COOH) and their ester derivatives (A AE BH(Br)COOX, X = Me, Et, i-Pr) [2,6,20], amine-dibromocarboxyborane methyesters (A AE BBr 2 COOMe) [20], salts of diaminhydrocarboxyboronium cations [AA 0 B(H)COX] + (X = OH, OMe) [19], cyclic diazaborolidinium and diazaborinanium ions [[C n N 2 B](Y)COX] (n = 2-4; Y = H, Br; X = OH, OMe) [2], as well as amine-dicarboxyboranes and their ester and amide derivatives A AE BH(COX) 2 (X = OH, OMe, NHEt) [21].…”

Synthesis, Characterization, and Bromine Substitution of Diamine Complexes of Carboxyborane and Methoxycarbonylborane. Diazabora Rings Containing B-Carboxyl and B-Carboxylato Groups

“…The biological role of these complexes is still being explored. ,, With respect to these biological and pharmacological activities we focused our efforts on the synthesis and characterization of boron-substituted derivatives, a type of compounds, which have attracted less attention so far. To date only few derivatives of the type amine·BH(R)COX (R = alkyl, X = OR, NR 2 ) , and a couple of carboxylated diazadiborinanes and diazadiborolidines , have been prepared. We planned to attach different substituents to boron via the brominated derivatives of carboxyboron compounds, as intermediates, taking advantage of the good leaving character of the bromine.…”