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Search for "borane" in Full Text gives 97 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives
Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226
- tetracyclic moieties are planar. The benzophosphole-fused indoles, such as phosphine oxide, phospholium salt, and borane complex, exhibited strong photoluminescence in dichloromethane (Φ = 67–75%). Keywords: benzophospholo[3,2-b]indole; DFT calculation; molecular structure; phosphole derivatives
- benzophosphole-fused indole derivative and its various functionalized analogs such as the corresponding phosphine oxide, phosphonium salt, and borane–phosphine complex. Results and Discussion The synthesis of the parent tetracyclic molecule 10-phenyl-[1]benzophospholo[3,2-b]-N-methylindole (3), is shown in
- , respectively. The reaction of 3 with methyl triflate afforded phospholium triflate 7. Phosphole 3 was treated with chloro(dimethyl sulfide)gold in CH2Cl2, resulting in P-complexation and thus affording the gold complex 8. The borane complex 9 was readily prepared from 3 by treating with borane in THF. The
Phosphonic acid: preparation and applications
Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219
- that finally led to the formation of the phosphonodiamidate 100. The reduction of the nitro function and the hydrolysis under acidic conditions of the phosphonodiamide produced the phosphonic acid 101 [211]. As a last example, lithiated diaminophosphine borane 102 was added to imine to produce the bis
- (diethylamino)phosphone borane 103 (Figure 28C). Then acidic hydrolysis conditions and likely air oxidation produced the phosphonic acid 104 [209]. Phosphonodiamide, which is more robust than phosphonate towards some nucleophilic species like a phosphide anion (R2P-Li), was used to prepare triarylphosphine
The chemistry and biology of mycolactones
Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159
Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine
Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145
- amides 4a–c employing a THF solution of borane (yields 82–93%; see Supporting Information File 1 and Scheme 2). The synthesis of N-(2-aminobenzyl)amides 4a–k was achieved by selective N-acylation of 2-ABA or its N-substituted derivatives 3a–c, whose preparation is depicted in Scheme 2. In spite of the
Total syntheses of the archazolids: an emerging class of novel anticancer drugs
Beilstein J. Org. Chem. 2017, 13, 1085–1098, doi:10.3762/bjoc.13.108
- any traces of water which were shown to lead to unfavourable isomerization pathways. Finally, an oxazaborolidine-assisted borane reduction [78] set the stereogenic center at C15 and global deprotection gave synthetic archazolid A, which proved to be fully identical with a natural sample, thus
- Scheme 9. After reduction the alcohol was protected with TIPS and the TBS ether was cleaved by acetic acid to get to the primary alcohol 43. The reduction with (S)-alpine borane was highly diastereoselective (dr > 20:1). Following this sequence over 6 steps the two stereogenic centers at C7 and C8 were
Highly reactive, liquid diacrylamides via synergistic combination of spatially arranged curing moieties
Beilstein J. Org. Chem. 2017, 13, 372–383, doi:10.3762/bjoc.13.40
- synthesis of 12 and other similar derivatives through a multistep reaction with the final step comprising the treatment of N,N'-dipropylperhydropyridazine-3,6-dione with a borane solution in THF [31]. Considering the high reactivity of 7 and the assumption, that the allylic double bond to the halide is
The reductive decyanation reaction: an overview and recent developments
Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30
- case the two-step protocol is followed by a lactamization and the one-pot reduction of ester and lactam groups of 18. The authors proposed a reductive anionic chain mechanism described in Scheme 10. The exposure of 14a to BH3 generates a borane–amine complex 20 whose fragmentation could be promoted by
- NaBH4. The resulting imine 21 is reduced by BH3 with the help of the cyanoborohydride anion. The formed anion 22 abstracts a proton from complex 20 to produce 23 or 24 and regenerate 21 and BH3CN−. A set of experiments supports this proposal. Notably, borane is the major hydride source for the reduction
- , malononitriles are reacting with a slight excess of NHC-borane 71, in refluxing t-BuOH with DTBP (di-tert-butylperoxide) as radical initiator. The yields are attractive while roughly comparable amounts of boryl nitriles 74 and 75 are formed (Scheme 23). Malononitriles 72d,e are successfully reduced to 73d,e
From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer
Beilstein J. Org. Chem. 2016, 12, 2673–2681, doi:10.3762/bjoc.12.264
- .12.264 Abstract The mesomeric betaine imidazolium-1-ylphenolate forms a borane adduct with tris(pentafluorophenyl)borane by coordination with the phenolate oxygen, whereas its NHC tautomer 1-(2-phenol)imidazol-2-ylidene reacts with (triphenylphosphine)gold(I) chloride to give the cationic NHC complex [Au
- ppm. Minute traces of water protonate the anionic NHC 7 spontaneously to give 6A/B without any traces of decomposition products. The betaine 6A reacted with tris(pentafluorophenyl)borane in dioxane at reflux temperature to give the borane adduct 8. The proton attached to C-2 of the imidazolium ring
- (crystallographic numbering, cf. Figure 2: C9) is clearly detectable at δ = 9.22 ppm in DMSO-d6, while the boron and fluorine atoms give resonance frequencies at δ = −3.45 ppm, and δ = −133.91, −159.97, −165.18 ppm in the 11B NMR and 19F NMR spectra, respectively. A single crystal X-ray analysis of the borane
A direct method for the N-tetraalkylation of azamacrocycles
Beilstein J. Org. Chem. 2016, 12, 2457–2461, doi:10.3762/bjoc.12.239
- quaternary amine species. A number of alternative approaches have been investigated, with differing degrees of success. For example Alcock et al. deployed a two-step route using acid chlorides to first form an intermediate amide, and then reduced this with borane in THF to the tertiary amine; yields were
A detailed view on 1,8-cineol biosynthesis by Streptomyces clavuligerus
Beilstein J. Org. Chem. 2016, 12, 2317–2324, doi:10.3762/bjoc.12.225
- proceeds via (R)- or (S)-6, by determination in which of the distinguishable diastereotopic positions the label ends up. The synthesis of the two enantiomers of (1-2H)GPP (Scheme S1, Supporting Information File 1) was performed by Alpine borane reduction [29] (both enantiomers of this reagent are
Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides
Beilstein J. Org. Chem. 2016, 12, 2293–2297, doi:10.3762/bjoc.12.222
- decreases the free energy of the second formal Mannich reaction, thus improving the reaction rate and chemoselectivity of the [4 + 2] cycloaddition. To extend the usefulness of this reaction, we demonstrate that the adduct can be efficiently reduced with borane. As shown in Scheme 2, 3a was readily reduced
DNA functionalization by dynamic chemistry
Beilstein J. Org. Chem. 2016, 12, 2136–2144, doi:10.3762/bjoc.12.203
- potassium bromide substitution under overall retention of configuration due to double inversion. Next, the subsequent reduction of carboxylic acid 6 to alcohol 7 was achieved by borane dimethyl sulfide (BMS) under dry conditions. The reaction between alcohol 7 and 3-mercaptopropanenitrile (8) resulted in
Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines
Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174
- substituent, each with a different means of cyclisation. A versatile and stable quinolin-2-one intermediate was identified, which could be reduced to the corresponding THQ with borane reagents, or to the DHQ with diisobutylaluminium hydride via a novel elimination that is more favourable at higher
- larger scales was slightly lower, though the DHQ was still isolated in a satisfactory 66% yield on one gram scale. Unlike borane, LiAlH4 and similar reagents, DIBAL did not cause de-iodination, even with larger excesses (up to 2 equivalents). There are few references to this type of reaction in the
A T-shape diphosphinoborane palladium(0) complex
Beilstein J. Org. Chem. 2016, 12, 1573–1576, doi:10.3762/bjoc.12.152
- (CyDPBPh)Pd(0) 9, which was characterized by X-ray analysis. Keywords: ambiphilic ligand; coordination chemistry; diphosphinoborane; organometallics; palladium; Introduction The amplification of traditional bidentate chelating L2-type ligands with a tethered borane functionality (e.g., Bourissou’s
- diphospinoborane (o-PR2-C6H4)2BR’ ligand RDPBR’) has received considerable attention [1][2][3], with first catalytic applications emerging [4]. The acyclic boron group in these ligands can adopt a variety of coordination modes (Figure 1) [5]. The borane can act as a σ-acceptor ligand in case of η1-B coordination
- chelating diphosphine, such as in Hofmanns Rucaphos complexes 6, are very scarce [11]. While the dative Pd→B bond is strong in zerovalent Pd(0) DPB complexes such as 2, only weak Pd→B interactions have been observed for the respective Pd(II) complexes [7][12]. Discrimination by the borane functionality
Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms
Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273
- iodide 97. The following palladium-catalyzed B-alkyl Suzuki–Miyaura cross coupling between the borane derived from alkene 98 and vinyl iodide 97 furnished a Z-configured alkene. Deprotection of the trimethylsilyl ether then afforded alcohol 99. A rhodium(II)-catalyzed O–H insertion reaction of the
A facile synthetic route to benzimidazolium salts bearing bulky aromatic N-substituents
Beilstein J. Org. Chem. 2015, 11, 1656–1666, doi:10.3762/bjoc.11.182
- can be tuned and, based on these properties, they possess great electronic flexibility. These ligands or catalysts reached a prominent position in the mentioned fields of chemistry. It is noteworthy that on the material’s side NHC-type carbene–borane adducts and metal complexes of them can also be
The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry
Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134
- this account each step was performed and optimised individually in flow, with analysis and purification being accomplished off-line. The synthesis commences with the reduction of the advanced intermediate ketone 47 using a solution of pre-chilled borane–THF complex (48) to yield alcohol 49 (Scheme 8
Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test
Beilstein J. Org. Chem. 2014, 10, 2729–2737, doi:10.3762/bjoc.10.288
- combustion analysis is not suitable for this type of nanodiamond derivatives. The dicyanopyrazine conjugate 4 can be submitted to a reduction of the nitrile groups using borane solution in THF. This mild yet efficient reaction leads to the complete transformation of the nitriles to amino groups as evidenced
- : negative, zetapotential: not measured as no stable colloidal solution in water was obtained. Particle size: 15 nm (acetone). Synthesis of 5: 65 mg of 4 was suspended in 5 mL BH3∙THF (1 M) and heated for 20 h under nitrogen atmosphere at 50 °C. Excess borane was decomposed by adding 2 N HCl. The diamond
Derivatives of the triaminoguanidinium ion, 3. Multiple N-functionalization of the triaminoguanidinium ion with isocyanates and isothiocyanates
Beilstein J. Org. Chem. 2014, 10, 2255–2262, doi:10.3762/bjoc.10.234
- was combined with benzaldehyde and hydratropic aldehyde to furnish the corresponding tris(imines), which were converted into 1,2,3-tris(benzylamino)guanidinium salts by catalytic hydrogenation in the former, and by borane reduction in the latter case. The resulting alkyl-substituted
- no success either. According to a procedure by Casarini et al. [19] compound 5 could finally be obtained. This procedure uses dimethylaminoborane/p-toluenesulfonic acid, where the acid serves as an activator to release free borane. With a large excess of p-toluenesulfonic acid an anion exchange also
Atherton–Todd reaction: mechanism, scope and applications
Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117
- expected phosphoramidate was jointly isolated with 5 to 10% of thiophosphoramidate resulting from a cyclization reaction. The chiral phosphoramidates (Scheme 32-ii and iii) were tested as a chiral catalyst for the nucleophilic addition of diethylzinc [107] on benzaldehyde or for the asymmetric borane
Preparation of phosphines through C–P bond formation
Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106
- the corresponding phosphine–borane complex [16][17]. The phosphine–borane complex is a stable intermediate toward the free phosphine. If necessary the boranato group can be removed by treatment with an excess of amine [18]. However, not all phosphines are prone to oxidation and show good air-stability
- preparative HPLC or recrystallization. Nucleophilic substitution of pure diastereomer (RP)-2a with methyllithium afforded the phosphine–borane (S)-4 with 94% enantiomeric excess. The substitution resulted in inversion of the configuration at the phosphorus center. Deboranation of the air stable borane adduct
- result of the reaction between bis(diethylamino)alkylphosphine 6 and ephedrine, followed by protection with borane. The subsequent stereoselective ring opening of compound 7 with an organolithium reagent gives way to acyclic products 8 with retention of configuration at the phosphorus center. These
Addition of H-phosphonates to quinine-derived carbonyl compounds. An unexpected C9 phosphonate–phosphate rearrangement and tandem intramolecular piperidine elimination
Beilstein J. Org. Chem. 2014, 10, 883–889, doi:10.3762/bjoc.10.85
- (R/S). The homologous aldehyde can be prepared by oxidation of the double bond in a hydroboration–oxidation sequence, however, the presence of the nitrogen atoms, particularly that of the tertiary amino group of quinuclidine, may be troubleshooting [28][29]. Borane complexes with heteroaromatic and
- aliphatic amines are considered inconveniently stable in protic solvents (water, alcohols) and dissociate only at an elevated temperature [30]. Most probably, in our case the formation of the amine–borane complex proceeded faster than the hydroboration of the vinyl group. When compound 2 was reacted with
- complexed forms (borane-tertiary amino group). Again, step-by-step approach and separation of the intermediate appeared more profitable. First, the alcohol 7 was synthesized by hydroboration of the substrate with BH3·THF under an inert atmosphere followed by oxidation of the intermediate borane 5 complex
Aminofluorination of 2-alkynylanilines: a Au-catalyzed entry to fluorinated indoles
Beilstein J. Org. Chem. 2014, 10, 449–458, doi:10.3762/bjoc.10.42
- to C-3 fluorinated indole derivatives was less investigated. Fluorination of trialkylstannylindole derivatives with cesium fluoroxysulfate or Selectfluor was investigated for the synthesis of the corresponding 3-fluoroindoles [17]. A borane–tetrahydrofuran complex has been used to study the reduction
Cyclic phosphonium ionic liquids
Beilstein J. Org. Chem. 2014, 10, 271–275, doi:10.3762/bjoc.10.22
- , BrMg(CH2)4MgBr and BrMg(CH2)5MgBr respectively. The resultant cyclic phosphines are air sensitive and therefore were allowed to react with BH3·THF to provide the air-stable 1-n-butylphospholane–borane and 1-n-butylphosphinane–borane complexes that were purified by silica-gel chromatography. The pure
- compounds were then treated under nitrogen with 1,4-diazabicyclo[2.2.2]octane (DABCO) at 80 °C to remove the borane, and the resultant mixture was purified in a nitrogen-filled glove box on a short silica-gel column. The pure cyclic phosphines (1-n-butylphospholane and 1-n-butylphosphinane) were allowed to
- -phenylphospholane–borane complex, followed by silica-gel chromatography and then removal of the borane with DABCO, to give the pure 1-phenylphospholane. The six-membered cyclic phosphine, which appears to be less air sensitive than the 1-butylphosphinane species, was purified in open air using a short column of
One-pot synthesis of cyanohydrin derivatives from alkyl bromides via incorporation of two one-carbon components by consecutive radical/ionic reactions
Beilstein J. Org. Chem. 2014, 10, 150–154, doi:10.3762/bjoc.10.12
- work in collaboration with Dennis Curran has revealed that, with the use of NHC-borane [18], hydroxymethylation of aromatic iodides can be attained [19]. All these reactions consist of the combination of radical formylation with CO and ionic hydride reduction by hydride reagents (Scheme 1, reaction 1
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