Synthesis and characterization of monosubstituted borane adducts of diethyl [(dimethylamino)methyl]phosphonate

Mittakanti, M.; Charandabi, M. R. M. D.; Morse, Karen W.

doi:10.1021/ic00342a033

Cited by 10 publications

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“…The synthesis of 5 was attempted by acidic hydrolysis of the known [amine-bis( C -methoxy- N -ethylimidate)hydroboron(2+)] cations ( 6 ): 29 These experiments were based on literature data stating that hydrolyses of C -alkoxy- N -alkylimidates in acidic media typically result in the formation of carboxylic acid esters and some amine-alkoxycarbonylboranes are known to be synthesized from [amine-( N -ethylnitrilium)dihydroboron(1+)] cations via amine-( C -alkoxy- N -ethylimidate)dihydroboron(1+)] species. , Therefore, the hydrolyses of 6a,b,f , which were readily obtained by nucleophilic addition of methanol to 1a,b,f , were systematically studied (basically by 1 H NMR monitoring) at various pH values. Our findings, different from those expected, can be summarized in Scheme 2.…”

Section: Resultsmentioning

confidence: 99%

Syntheses of the First Amine-dicarboxyboranes and Their Bis(methylester) and Bis(N-ethylamide) Derivatives

Győri

Berente

2001

Inorg. Chem.

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Amine-bis(N-ethylcarbamoyl)boranes [A.BH(CONHEt)(2), 3; A = trimethylamine (Me(3)N, a), quinuclidine (Q, b), pyridine (py, f), 4-picoline (pic, g)] have been prepared after deprotonation of [amine-bis(C-hydroxy-N-ethylimidate)hydroboron(2+)] cations (2), which were formed by the hydrolysis of [amine-bis(ethylnitrilium)hydroboron(2+)]tetrafluoroborates (1). Numerous representatives of 3 [A = diethylamine (Et(2)NH, c), piperidine (pip, d), pyrrolidine (pyrr, e), 4-aminopyridine (4-NH(2)-py, h), 4-(dimethylamino)pyridine (DMAP, i), imidazole (Him, j), 1-methylimidazole (Mim, k)] have been prepared by base exchange reactions from 3a. 3a-e are extremely stable in aqueous media, either acidic or alkaline, probably because of the considerable steric hindrance of possible reaction centers. However, they were transformed into amine-dicarboxyboranes [A.BH(COOH)(2), 4a-e] in acidic medium under vigorous conditions (100-130 degrees C). This transformation was accompanied by significant decomposition, probably owing to the protonation on the N atom, resulting in the rupture of the B-N bond. As an exception, 4b, where N atom in a rigid bicycle is not prone to attacks, could be isolated in very good yield. On the other hand, amine-bis(N-ethylcarbamoyl)boranes containing amines with sp(2)-hybridized N atoms (3f-k) undergo complete decomposition under similar conditions probably because of the increased hydridic character of the hydrogen adjacent to boron. Base exchange reactions starting from 4b resulted in the ammonium salts of 4c-e, h, i of composition [A.BH(COOH)(COO(-))][AH(+)], which in turn could be transformed into the diacids 4, except 4h, by protonation. As salt formation indicates, the 4 compounds are stronger acids as univalent acids than the corresponding A.BH(2)(COOH) complexes. 4a-e, i were readily esterified into amine-bis(methoxycarbonyl)boranes (5a-e, i) in methanol, employing a catalytic amount of HBr. 5a-e, i are stable in alkaline medium but are readily hydrolyzed in acidic medium. Hydrolysis of [amine-bis(C-methoxy-N-ethylimidate)hydroboron(2+)] cations did not give the corresponding bisesters 5 in alkaline, neutral, or acidic medium.

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Section: Resultsmentioning

confidence: 99%

Syntheses of the First Amine-dicarboxyboranes and Their Bis(methylester) and Bis(N-ethylamide) Derivatives

Győri

Berente

2001

Inorg. Chem.

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“…Previous papers in the literature describe the ethylation reactions (Scheme , ii) employing 50−100% excess of Et 3 OBF 4 and 24−72 h reaction times. ,,− In contrast, we have found that diamine-bis(cyanoboranes) 1 could be completely converted into their bis(ethylnitrilium dihydroborane) tetrafluoroborates 2 in 2−3 h using a small (3−5%) excess of Et 3 OBF 4 .…”

Section: Resultsmentioning

confidence: 99%

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

Győri

Berente

1998

Inorg. Chem.

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DA·2BH2CN (1) [DA = N,N,N‘,N‘-tetramethylethanediamine (TMEDA, a), N,N,N‘,N‘-tetramethylpropanediamine (TMPDA, b), and N,N,N‘,N‘-tetramethylbutanediamine (TMBDA, c)], (DA·2BH2CNEt)(BF4)2 (2), and DA·2BH2COOH (3) complexes were prepared from Me2S solution of (BH2CN) n (→ 1 → 2 → 3) in fast procedures, differently from those usually applied, in good yields. Dimethyl esters (4) were prepared from 3 with methanol in very fast reactions catalyzed by HBr. 3 and 4 were transformed into DA·BH2COOH (5a,b) and DA·BH2COOMe (6) with DA in THF. Bromination of 3 in aqueous HBr yielded diamine-bis(monobromocarboxyboranes) (7), in vigorous conditions diamine-bis(dibromocarboxyboranes) (9) were produced. N-Bromosuccinimide in methanol transformed 3a,b directly into diamine-bis(bromomethoxycarbonylboranes) (8a,b). BrH·DA·BH(Br)COOH (10a,b) could be prepared from 5a,b with bromine in strongly acidic medium. N-Deprotonated 10a quickly transformed into a five-membered cyclic cation [TMEDA·BHCOOH]+ (cation in 12a) in both water and methanol. Thus, this ion was formed by dissolution of 10a in water, bromination of 5a or destroying one of the borane moieties in 7a by a base. N-Deprotonated 10b in water decomposed with a pH-dependent rate, but in methanol, in the presence of base, it transformed into a six-membered cyclic cation [TMPDA·BHCOOH]+ (cation in 12b). 8a,b could also be transformed into cyclic cations by destroying one of their borane moieties in methanol, (8b in absence of acids only). All cations were prepared as bromide, hexafluorophosphate and tetraphenylborate salts. pK a values of 12a,b (pK a = 5.5−5.6) are 3 units lower than those of amine-carboxyboranes. Zwitterions (18a,b) formed by their deprotonation were prepared. Cyclic cation [TMEDA·B(Br)COOH]+ (cation in 19a) formed on destroying one dibromocarboxyborane of 9a. This cation, quite a strong acid (pK a ≈ 4.2), was prepared as hexafluorophosphate and tetraphenylborate salt. The latter was transformed with aqueous KOH into the corresponding zwitterion (21a).

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ChemInform Abstract: Synthesis and Characterization of Monosubstituted Borane Adducts of Diethyl ((Dimethylamino)methyl)phosphonate.

1990

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Synthesis and characterization of monosubstituted borane adducts of diethyl [(dimethylamino)methyl]phosphonate

Cited by 10 publications

References 0 publications

Syntheses of the First Amine-dicarboxyboranes and Their Bis(methylester) and Bis(N-ethylamide) Derivatives

Syntheses of the First Amine-dicarboxyboranes and Their Bis(methylester) and Bis(N-ethylamide) Derivatives

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

ChemInform Abstract: Synthesis and Characterization of Monosubstituted Borane Adducts of Diethyl ((Dimethylamino)methyl)phosphonate.

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