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Search for "diazo compound" in Full Text gives 52 result(s) in Beilstein Journal of Organic Chemistry.
Gold-catalyzed ethylene cyclopropanation
Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7
- frequently is avoided upon maintaining a low diazo compound/catalyst ratio, employing slow addition devices to incorporate a solution of the diazo reagent into the reaction mixture containing the olefin and the catalyst. Unfortunately, the use of ethylene as the olefin requires a pressure vessel and thus the
Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles
Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256
- -(phenylselanyl)-1H-pyrazol-5-amine was submitted to an oxidative dehydrogenative coupling to produce a diazo compound confirmed by X-ray analysis. Keywords: diaryl diselenide; diazo compound; 1H-pyrazole; molecular iodine; multicomponent reaction; Introduction Selenium-containing compounds are of great
Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds
Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200
- 4 and 5). The reactions of tricyclic diazodiketone 1c and diazoindandione 1f in the presence of benzophenone as sensitizer proceeded in a similar way to diazo compound 1b under the optimal conditions affording hydrazones 2c,f in yields of 63 and 52%, respectively (Table 1, entries 10 and 13). An
Atom-economical group-transfer reactions with hypervalent iodine compounds
Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108
- of elemental nitrogen is lost over the course of the reaction. The overall AE is only diminished by the necessity to use two equivalents of the diazo compound (AE = 74% for 43b). Furthermore, an enantioselective version of this oxyalkynylation (for R1 = H) was developed [57]. Employing a chiral
One hundred years of benzotropone chemistry
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
- benzotropones 11 and 12 (Scheme 14 and Scheme 33) [78]. Diazo compound 76 was prepared from 4,5-benzotropone hydrazone under oxidative conditions. Irradiation of matrix-isolated 7-diazo-7H-benzo[7]annulene (76) afforded a mixture of triplet 7H-benzo[7]annulenylidene (77), 2,3-benzobicyclo[4.1.0]hepta-2,4,6
- ], while the allenic rearrangement product 183 for the carbene 75 was not detected in the photolysis of a diazo compound (Scheme 33) [78]. 2,3-Benzotropone (12) was converted to gem-dichloride 187 to achieve diazirine as carbene precursor (Scheme 33) [77][144]. 3.2.2. Ring-expansion reactions via a tropone
Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes
Beilstein J. Org. Chem. 2017, 13, 2569–2576, doi:10.3762/bjoc.13.253
- diazomalonate, which is unusual for Rh(II)-catalyzed reactions of this diazo compound [26]. Application of more active catalysts like dirhodium tetraoctanoate or tetrapivalate makes it possible to reduce the reaction time at reflux in benzene to 2 h (Table 1, entries 3 and 4). In the case of dirhodium
Hydrolysis, polarity, and conformational impact of C-terminal partially fluorinated ethyl esters in peptide models
Beilstein J. Org. Chem. 2017, 13, 2442–2457, doi:10.3762/bjoc.13.241
- added to a solution of N-acetylproline in water (2.5 mL). The mixture was stirred at room temperature for 16 hours. Then, trifluoroacetic acid (0.1 mL) was added, and the mixture was stirred for an additional hour to quench residual diazo compound. The solution was then freeze-dried. Purification of the
- crude material on a silica gel column afforded 30 mg of 4 as a clear oil (yield 20%). When the diazo compound was generated in an acetonitrile/water (1:1) mixture (4.5 mL), no heating was applied, and N-acetylproline was added to the yellowish mixture 5 min after mixing the amine with the nitrite. From
Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective
Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220
- reaction with α-bromo ketoximes 1 (Scheme 36). The reaction requires a copper catalyst, which transforms the diazo compound 96 into a metal carbene complex 97. The latter reacts with a nitrosoalkene intermediate NSA (formed from α-bromo ketoxime 1) producing isoxazoline 93 with recovery of the catalyst
A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes
Beilstein J. Org. Chem. 2017, 13, 1900–1906, doi:10.3762/bjoc.13.185
- applied [14]. Another approach, which opens access to diverse ethenes, is the ‘two-fold extrusion reaction’, which comprises the [3 + 2]-cycloaddition of a diazo compound with a thiocarbonyl dipolarophile and subsequent elimination of N2 followed by sulfur extrusion [15][16][17]. In our continuing studies
Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis
Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51
- to maximize the formation of the diazo compound (Scheme 18) [87]. Starting from this initial investigation, Ley and co-workers developed an elegant application of this strategy for a sequential formation of up to three C–C bonds in sequence, by an iterative trapping of boronic acid species. The
- sequence starts with the reaction of diazo compound 20, generated under flow conditions, and boronic acid 19 (Scheme 19). Further sequential coupling with diazo compounds 21 and 22 led to boronates 23 or protodeboronated products 24 at the end of the sequence (Scheme 19). With the aim to exploit the
On the cause of low thermal stability of ethyl halodiazoacetates
Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155
- bimolecular dimerization leading to azines; and 3) a reaction of the diazo compound with the solvent or a reactant prior to nitrogen extrusion. The fact that the decomposition rate of all halodiazoacetates showed first order kinetics and that t1/2 for 2b is independent of its concentration indicates that
- ) was included in the calculations even though the synthesis of this diazo compound has not been reported in the literature. We excluded 2c in our molecular modeling due to the need for a different basis set for iodine compared to the other halogens. We also included diethyl diazomalonate (2e, t1/2
Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates
Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121
- prepare phosponylpyrazoles 217 in the presence of KOH in MeOH in 73–95% yields (Scheme 44) [82]. Based on their explanation, the treatment of dimethyldiazomethylphosphonate 213 with a nucleophilic base generates diazo compound 215. The subsequent [3 + 2] cycloaddition reaction of 215 with Knoevenagel
Enantioselective carbenoid insertion into C(sp3)–H bonds
Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87
- -cuparenone (8) through the construction of a five-membered ring prepared by an enantioselective carbenoid insertion into a C(sp3)–H bond (Scheme 3) [34]. To carry out the cyclization, the carbenoid was formed by the action of Rh2(OAc)4 on the diazo compound 6. That intermediate intramolecularly inserted into
- the interaction of the diazo compound 28 and the dirhodium complex 27. In sequence, the reaction proceeds through the transition state TS-30 to release N2, and yields the carbenoid 31. The divalent carbon attached to the rhodium atom starts to interact with the hydrogen of the C(sp3)–H bond of the
- )–H when X = Ph or H. The first reason concerns the relative stability of the carbenoids 38-Ph and 38-H. The first one, prepared from the donor/acceptor diazo compound 36-Ph, is 10.9 kcal more stable than the carbenoid 38-H obtained from the acceptor diazo compound 36-H. This observation was
Evidencing an inner-sphere mechanism for NHC-Au(I)-catalyzed carbene-transfer reactions from ethyl diazoacetate
Beilstein J. Org. Chem. 2015, 11, 2254–2260, doi:10.3762/bjoc.11.245
- of a gold(I) source and a diazo compound. It was not until 2005 that the first example of this transformation was reported by our group [15][16], when the complex IPrAuCl (1) (IPr = 1,3-bis(diisopropylphenyl)imidazole-2-ylidene), in the presence of NaBArF4 (BArF4− = tetrakis(3,5-bis(trifluoromethyl
- two molecules of the diazo compound convert into an olefin and/or an azine (Scheme 4b), the second acting as a nucleophile attacking the metallocarbene intermediate [28]. However, our previous studies have shown that this gold-based catalytic system does not induce such non-desired carbene
- with the diazo compound and then evolution of nitrogen. However, that first step of substrate dissociation would be in disagreement with the observation of the enhancement of the reaction rate of nitrogen evolution when increasing the substrate:catalyst ratio, the dissociation of the substrate should
Olefin metathesis in air
Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221
- reaction with styrene, avoiding the use of hazardous diazo compound 7 [82]. Towards the end of 2013, a report by Olszewski, Skowerski and co-workers showed how a variety of commercially available catalysts (Figure 12) could be employed in air with nondegassed ACS grade green solvents. Their results were in
Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization
Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35
- successful procedure involving addition of Rh2(OAc)4 to a boiling 1:1.25 mixture of azirine 1a and diazo compound 2a in 1,2-dichloroethane (DCE) (procedure A) gave rise to oxazine 4a and azadiene Z-3a in 60 and 7% yields, respectively (Scheme 2, Table 1, entry 1). It was also shown that azadiene Z-3a did not
- -1,3-dienes with the C=C bond in Z-configuration have a sufficiently high activation barrier for cyclization and are usually stable up to 90–100 °C. Oxazine 4b was synthesized in a similar way from azirine 1b and diazo compound 2a (Table 1, entry 2), but in this case no traces of azadiene Z-3b were
- published procedure [25]. Diazo compound 2b slowly decomposes in the presence of Rh2(OAc)4 and 2,2-dimethyl-3-phenylazirine (1c) even at room temperature, but no conversion of the latter was observed according to 1H NMR spectroscopy. A satisfactory result was obtained, when the reaction was carried out at
Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines
Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197
- as well as oxazines 3a–c [10]. The corresponding ethyl 2-((E)-4-oxo-3-phenylpent-2-en-2-ylimino)acetate (E)-4j was not isolated from the reaction of azirine 5 with diazo compound 2b, probably due to its instability. Conclusion According to DFT calculations at the B3LYP/6-31G(d) level and experimental
- Cambridge Crystallographic Data Centre. Isoxazoles 1a [29], 1b [30], 1c–e [31], 1f,g [32] were prepared by the reported procedures. General procedure of reacting isoxazoles with diazo compounds. A long Schlenk tube containing a mixture of isoxazole (0.3–1.2 mmol) and diazo compound (1 equiv) in PhCF3 (1–2
- mL) was put into an oil bath preheated to 110 °C. To the vigorously stirred mixture, Rh2(OAc)4 (1–5 mol %) was added in one portion and stirred until N2 evolution has been stopped (10–15 min). An additional amount of diazo compound was added dropwise, and then the mixture was heated for an additional
C–H-Functionalization logic guides the synthesis of a carbacyclopamine analog
Beilstein J. Org. Chem. 2014, 10, 1564–1569, doi:10.3762/bjoc.10.161
- analog that still exhibits similar inhibitory activity on hedgehog-signaling. For the sake of brevity of the overall synthetic sequence we defined carbacyclopamine analog 2 (see Figure 1) as our primary target. Results and Discussion A retrosynthetic analysis identified diazo compound 3 as a key
- was thought to establish the C-nor-D-homo steroid system, and a gold-catalyzed amination/annulation/aromatization sequence was planned to install the pyridine F-ring. Diazo compound 3 originates from diene 4 through standard transformations, the latter being accessible from commercially available and
Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems
Beilstein J. Org. Chem. 2014, 10, 784–793, doi:10.3762/bjoc.10.74
- compound. Boiling an o-xylene solution of furanedione 1d and azirine 2a (1:1 ratio) gave bisadduct 18 in 34% yield (Scheme 6). This is less than when using the diazo compound as a source of acylketene, probably due to dimerization of ketene 6d under higher temperature. Compounds 3 and 17, stable at room
- . 4,5-Diphenylfuran-2,3-dione (1d) is the source of benzoylphenylketene 6d. Reaction of ketene 6d, generated from 2-diazo-1,3-diphenylpropane-1,3-dione, with azirine 2a was studied earlier [22]. Higher temperatures are needed to generate benzoylphenylketene 6d from furanedione 1d, than from the diazo
Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis
Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14
- formal [4 + 3] cycloaddition [82]. Starting from 4-methoxyphenol (90) Friedel–Crafts acylation and cyclization provided bicycle 91. Wittig olefination furnished benzofuran 92. Diazotransfer using p-ABSA yielded the crucial diazo compound 93, which was used in the following enantioselective
- -catalyzed cyclopropanation of silyl-enol-diazo compound 101 and Boc-protected pyrrole 147 resulted in the formation of intermediate cis-divinylcyclopropane 148, that rearranged under the reaction conditions to give the corresponding highly substituted bridged cycloheptadiene 149. Deprotection of the enolate
- coworkers [174] applied the DVCPR in the core structure synthesis of actinophyllic acid (218, see Scheme 25) [175]. Subjection of diazo compound 213 to copper catalysis yielded vinylcyclopropane 214. Deprotonation and silyl ether formation resulted in intermediate cis-divinylcyclopropane 215, which smoothly
Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion
Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309
- -dicarbonyl compounds with cycloaliphatic thioketones. The study was aimed at (i) the determination of the key directions of these processes in dependence of the type of diazo compound and (ii) the identification of their usefulness for the synthesis of sulfur-containing heterocycles and derived compounds
- formation of these compounds can be rationalized by pathways presented in Scheme 2 [4][22]. 1) Pathway A implies the initial 1,3-dipolar cycloaddition between the diazo compound 2 and the С=S bond of thioketone 1 giving rise to 1,3,4-thiadiazoline 10. The latter is usually an unstable intermediate species
- the thiocarbonyl ylide 6 is also possible via an alternative pathway C, that implies interaction of a dioxocarbene (formed after thermal decomposition of the diazo compound) with the sulfur atom of the C=S group [4][7][8]. The subsequent intramolecular 1,5-electrocyclization of the same intermediate 6
α-Bromodiazoacetamides – a new class of diazo compounds for catalyst-free, ambient temperature intramolecular C–H insertion reactions
Beilstein J. Org. Chem. 2013, 9, 1407–1413, doi:10.3762/bjoc.9.157
- cycloaddition, ylide formation, cyclopropanation and C–H insertion reactions [1][2][3]. A generally useful modification of diazo compounds is the substitution of the α-hydrogen for an electrophile. This substitution can be effected in the presence of a base or starting from the metalated diazo compound, and
- which the α-substituent on the carbene carbon varies (see below). The α-phenyl analogue of β-lactam 5b has previously been prepared by carbene C–H insertion. In these reports, the base-promoted decomposition of a hydrazone and subsequent thermolysis of the diazo compound in, e.g., toluene under reflux
4-Pyridylnitrene and 2-pyrazinylcarbene
Beilstein J. Org. Chem. 2013, 9, 754–760, doi:10.3762/bjoc.9.85
- liquid N2 at −196 °C, or at 2092 cm−1 upon isolation in an Ar matrix at 10 K. The diazo compound is also formed on matrix photolysis of the triazole (Figure 1). Compound 22 can exist as s-Z and s-E conformers. One conformer dominates, absorbing strongly at 2092 cm−1; the other, minor absorption is at
- 2076 cm−1 (Figure 1). Warming the neat diazo compound to ca. −30 °C causes ring closure to triazole 24. Compound 24 can be isolated in up to 20% yield in preparative pyrolysis of 23 [16]. Further FVT of either 23 or 24 at ≥450 °C/10−3 mbar results in the formation of approximately equal amounts of the
- ) or triazole 24 in an Ar matrix at 7–10 K causes efficient ring expansion to the cyclic seven-membered ring ketenimine 20 as observed by IR spectroscopy (Figure 2). In the case of triazole 24, efficient ring opening to the diazo compound 22 happens first (Figure 1), so the latter is the immediate
Flow photochemistry: Old light through new windows
Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229
Continuous flow photolysis of aryl azides: Preparation of 3H-azepinones
Beilstein J. Org. Chem. 2011, 7, 1124–1129, doi:10.3762/bjoc.7.129
- expansion of 12, via 2H-azirine 3, affords didehydroazepine 4, which can be trapped by variety of nucleophiles to provide the corresponding azepine 5. Alternatively, intersystem crossing (ISC) of 12 gives rise to 32, which can dimerize to form diazo compound 6. Performing the reaction in the presence of
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