Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• sulfonamide derivatives 12 by reducing the nitro group to an amino group by catalytic hydrogenation followed by treatment with an arylsulfonyl chloride (Scheme 4). Alternatively, 5-aminopyrazoles 17 containing a cyclohexylmethyl- or phenylmethyl- sulfonamido group at position-3 were prepared by treating β

• cyanoacetaldehyde (7) with hydrazines. Synthesis of 5-aminopyrazoles and their sulfonamide derivatives. Synthesis of 5-aminopyrazoles, containing a cyclohexylmethyl- or phenylmethyl- sulfonamido group at position-3. Regioselective synthesis of 3-amino-2-alkyl (or aryl) thieno[3,4-c]pyrazoles 19. Solid supported

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• , C6F5SSCF3, CF3I as well as (CF3S)2 with (CF3)2S suggesting the following reaction mechanism (Scheme 53). N-Trifluoromethyl-N-nitrosobenzene sulfonamide has been used as a source of CF3• radicals. This reagent (obtained by reaction of CF3NO, NH2OH and benzenesulfonic acid chloride) reacts with organic

Recent advances in carbocupration of α-heterosubstituted alkynes

• Ahmad Basheer and
• Ilan Marek

Beilstein J. Org. Chem. 2010, 6, No. 77, doi:10.3762/bjoc.6.77

• the stoichiometric version, the reaction proceeds smoothly for the addition of alkyl and phenyl substituents but the yield is much lower for the addition of methyl (30% yield, not indicated in Scheme 11). Even when phenylethynylarene sulfonamide 25 is used as starting material, a single regioisomer 26

• centers. Carbocupration of alkynyl sulfonamide. Tandem carbocupration-sigmatropic rearrangement. Silylcupration of alkynyl sulfonamides. Carbocupration of P-substituted alkynes. Carbocupration of alkynylphosphonates. Carbocupration of thioalkynes. Tandem carbocupration-1,2-metalate rearrangement

Anion receptors containing thiazine-1,1-dioxide heterocycles as hydrogen bond donors

• Hong-Bo Wang,
• James A. Wisner and
• Michael C. Jennings

Beilstein J. Org. Chem. 2010, 6, No. 50, doi:10.3762/bjoc.6.50

• potential hydrogen bond donor strength with anionic guests. Alternatively, the possibility of deprotonation in some specific systems by basic anions such as carboxylates or fluoride can be employed as an indicator for these species. Regardless, the incorporation of sulfonamide functional groups has

• typically been realized synthetically by sulfonylation of an amine to form a sulfonamide product. This approach is somewhat limited, from a design perspective, in that the majority of examples to date consist of sulfonamides derived from a few commercially available starting materials such as

• heterocycle can be viewed as a cyclic, vinylogous sulfonamide that presents a different spatial, conformational and electronic relationship between the sulfonyl and NH subunits than that of a typical sulfonamide function (Figure 1B). It is a simple matter to access many such derivatives with this framework

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

Diastereoselective functionalisation of benzo-annulated bicyclic sultams: Application for the synthesis of cis-2,4-diarylpyrrolidines

• Susan Kelleher,
• Pierre-Yves Quesne and
• Paul Evans

Beilstein J. Org. Chem. 2009, 5, No. 69, doi:10.3762/bjoc.5.69

• Scheme 1, a Heck (Heck–Mizoroki) cyclisation [5][6][7][8][9] was employed to form the cyclic sulfonamide. Subsequently, it was shown that high stereofacial bias was achieved on hydrogenation, generating 2 as a single diastereoisomer. Treatment under dissolved metal reduction conditions afforded the cis

• demonstrates that we were able to utilise the functionalisation of bicyclic sulfonamide 5a featuring a Suzuki coupling and a diastereoselective hydrogenation to construct cis-2,4-diarylpyrrolidines in a diastereoselective manner. The epimerisation reaction which led to the formation of carboxylic acid 26

• . Possible explanation for the products formed in the dibromination of 5a and 5b. Lithiation–CO2 quench approach for the synthesis of 26 from vinyl bromide 24a. Suzuki–Miyaura cross-coupling of 24a and the diastereoselective hydrogenation of the resultant styrene adducts. Attempted sulfonamide double

A convenient method for preparing rigid-core ionic liquid crystals

• Julien Fouchet,
• Laurent Douce,
• Benoît Heinrich,
• Richard Welter and
• Alain Louati

Beilstein J. Org. Chem. 2009, 5, No. 51, doi:10.3762/bjoc.5.51

• −). UV–vis (CH2Cl2): λmax (ε, L·mol−1·cm−1) = 256 nm (10100). Elemental analysis for C22H35F3N2O4S, Cacld: C 56.08, H 7.16, N 6.59%. Found: C 55.84, H 6.86, N 5.40%. 1-[4-(Dodecyloxy)phenyl]-3-methyl-1H-imidazol-3-ium bis(trifluoromethane) sulfonamide (1e) 1a (0.101 g, 0.21 mmol) and lithium bis

• (trifluoromethane)sulfonamide (0.145 g, 0.51 mmol) were dissolved in water (3 mL) and stirred for 140 h. The precipitate was filtred and washed. Crystallization (chloroform/cyclohexane) provided 1e with a yield of 90% (0.121 g, 0.19 mmol). 1H NMR (300 MHz, CDCl3): δ = 0.89 (t, 3H, J = 6.8 Hz, CH3 aliphatic chain

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• equivalent of TDAE in acetone as solvent. The reaction mixture instantaneously turned deep red, with accompanying effervescence of nitrogen, and afforded the tetracyclic sulfonamide 65 in 60% yield along with indole (63) and indole sulfonamide 64 in 33% and 5% yield respectively (Scheme 8). Initial SET from

• , would result in the formation of the tetracyclic sulfonamide 65 (Scheme 9). Indole (63) and indole sulfonamide 64 can be formed via the indolinyl radical intermediate 71 (Scheme 10). The formation of the indolinyl radical 71 could be envisaged by abstraction of the hydrogen atom (1,5-hydrogen

• precedent for this radical fragmentation of the sulfonyl group comes from the previous work of our group [71], where a similar indolinyl radical underwent a radical cleavage of N-S bond to eliminate the sulfonyl group. Indole sulfonamide 64 could be explained by deprotonation of radical 71 by TDAE to form

N-Arylation of amines, amides, imides and sulfonamides with arylboroxines catalyzed by simple copper salt/EtOH system

• Zhang-Guo Zheng,
• Jun Wen,
• Na Wang,
• Bo Wu and
• Xiao-Qi Yu

Beilstein J. Org. Chem. 2008, 4, No. 40, doi:10.3762/bjoc.4.40

• reaction. In an endeavor to expand the scope of the above methodology, the catalytic system was also applied to imides, amines, amides and sulfonamides. Such coupling was found to give the desired N-arylation products in moderate yields, as shown in Table 5, except for sulfonamide, which afforded the

• , amides, imides, and sulfonamide with phenylboroxine using copper salt/EtOH systema. Supporting Information Supporting Information File 112: N-Arylation of amines, amides, imides and sulfonamides with arylboroxine catalyzed by simple copper salt/EtOH system Acknowledgements This work was financially

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

• Andrew Kennedy,
• Adam Nelson and
• Alexis Perry

Beilstein J. Org. Chem. 2005, 1, No. 2, doi:10.1186/1860-5397-1-2

• diastereoselective functionalisation of piperidines were developed using a racemic model ring system. Oxidative ring expansion[38] of the 2-furyl sulfonamide 11, prepared by addition of n-butyl lithium to the N-tosyl imine of 2-furaldehyde,[39] was followed by protection to yield the piperidin-3-one 12 (Scheme 3

• materials were prepared from the 1,3-amino alcohol derivatives 1,3syn- and 1,3anti-10 (Scheme 6). Treatment of the difuryl 1,3-sulfinimido alcohols 1,3syn- and 1,3anti-10 with NBS in buffered THF-water precipitiated sulfonamide oxidation and two-directional ring expansion of both furan rings;[50] the crude

• structural complexity had been introduced as a consequence of the two-directional nature of the approach (sulfonamide oxidation, two oxidative ring expansions, two protection reactions and one N,O acetal substitution reaction). The stage was set for two-directional functionalisation of the heterocyclic rings