Asymmetric organocatalytic decarboxylative Mannich reaction using β-keto acids: A new protocol for the synthesis of chiral β-amino ketones

• Chunhui Jiang,
• Fangrui Zhong and
• Yixin Lu

Beilstein J. Org. Chem. 2012, 8, 1279–1283, doi:10.3762/bjoc.8.144

• , entry 1). Quinine-derived sulfonamide [40], β-isocupreidine (β-ICD) [41][42] and biscinchona alkaloid (DHQ)2AQN were all found to be poor catalysts (Table 1, entries 2–4). On the other hand, cinchona alkaloid derived bifunctional thiourea tertiary amine catalysts afforded much improved results (Table 1

Synthesis and characterization of Sant-75 derivatives as Hedgehog-pathway inhibitors

• Chao Che,
• Song Li,
• Bo Yang,
• Shengchang Xin,
• Zhixiong Yu,
• Taofeng Shao,
• Chuanye Tao,
• Shuo Lin and
• Zhen Yang

Beilstein J. Org. Chem. 2012, 8, 841–849, doi:10.3762/bjoc.8.94

• [39][40]. It is noteworthy that some polar groups, including amino, hydroxy and sulfonamide, could not tolerate the conditions of Higa cyclization, and had to be introduced through transformation reactions after the N-acylation step. As depicted in Scheme 3, NH2-derivative 7m was prepared from the NO2

Synthetic approaches to multifunctional indenes

• Neus Mesquida,
• Sara López-Pérez,
• Immaculada Dinarès and
• Ermitas Alcalde

Beilstein J. Org. Chem. 2011, 7, 1739–1744, doi:10.3762/bjoc.7.204

• as the most suitable way of functionalizing the 5-position of the indene, e.g., by changing the aryl(heteroaryl) structural motif of a sulfonamide moiety (Scheme 1). This route proceeded in three steps, and allowed the representative (3-indenyl)acetic acids 4 to be conveniently prepared from

Continuous-flow enantioselective α-aminoxylation of aldehydes catalyzed by a polystyrene-immobilized hydroxyproline

• Xacobe C. Cambeiro,
• Rafael Martín-Rapún,
• Pedro O. Miranda,
• Sonia Sayalero,
• Esther Alza,
• Patricia Llanes and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2011, 7, 1486–1493, doi:10.3762/bjoc.7.172

• ], binaphthyl-derived amines [22][23][24], pyrrolidin-2-yl-tetrazoles [25][26][27][28], thiaproline [29], 2-aminomethylpyrrolidine sulfonamide [30] and sulfonylcarboxamide [31], have been successfully used to promote the reaction. As a matter of fact, the rapid development of the methodology for the asymmetric

Amine-linked diglycosides: Synthesis facilitated by the enhanced reactivity of allylic electrophiles, and glycosidase inhibition assays

• Ian Cumpstey,
• Jens Frigell,
• Elias Pershagen,
• Tashfeen Akhtar,
• Elena Moreno-Clavijo,
• Inmaculada Robina,
• Dominic S. Alonzi and
• Terry D. Butters

Beilstein J. Org. Chem. 2011, 7, 1115–1123, doi:10.3762/bjoc.7.128

• unsaturated glycoside 4 to be achieved; phosphomolybdic acid [32] gave the product (α:β, 8:1) in 63% yield. Deacetylation of 4 and regioselective silylation of the primary alcohol gave the threo allylic alcohol 2. The sulfonamide nucleophiles 6, 7 and 9 were prepared from the corresponding amines 5 [33] and 8

• [34], as described previously [6], with only one equivalent of the sulfonylating agent so as to avoid bis-sulfonamide formation. Mixing equimolar equivalents of the erythro allylic alcohol 1 and the glucose-6-nosylamide 6 with DIAD and triphenylphosphine resulted in a smooth coupling reaction to give

• conditions that had failed to give coupling reactions between a primary alcohol and a sulfonamide at a secondary carbohydrate position, or a secondary alcohol and a sulfonamide at a primary carbohydrate position, in our earlier study [6]. Coupling of this threo alcohol 2 with sulfonamide nucleophiles (6, 7

Intramolecular hydroamination of alkynic sulfonamides catalyzed by a gold–triethynylphosphine complex: Construction of azepine frameworks by 7-exo-dig cyclization

• Hideto Ito,
• Tomoya Harada,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2011, 7, 951–959, doi:10.3762/bjoc.7.106

• linker chain of the alkynic N-tosylsulfonamide 4a (Table 3). The introduction of the substituents at the α or β positions relative to the alkyne moiety caused a significant decrease in the reactivity, but the cyclization of the substituted alkynic sulfonamide 4g–l proceeded smoothly, with 2.5–5.0 mol

• -dig cyclization in good yields (Table 3, entries 4–6). Among the cyclization products (5a–l) described above, only the β,β-diphenyl-substituted sulfonamide 5k was contaminated with a small amount of exomethylene product 6k (Table 3, entry 5). It should be noted that the geminal disubstitution in 4j–l

• reaction time and product yield. The reaction of N-tosylbenzamide 4n with L1 afforded the benzene-fused ε-caprolactam 6n within an exomethylene structure in 97% yield in an isomerically pure form (vide infra for discussion) (Table 4, entry 3). Sulfonamide 4o, with a cyclohexane-fused linker, also

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• method to construct synthetically useful four-membered carbocycles. Ye et al. reported a new type of gold(I)-catalyzed ring expansion of an non-activated alkynylcyclopropane/sulfonamide to obtain (E)-2-alkylidenecyclobutanamines [73]. For example, treatment of alkynylcyclopropane 159 with TsNH2 and 5 mol

• by the AuCl3/AgSbF6 catalyst and ionization of the starting material, which causes intramolecular nucleophilic addition of the sulfonamide unit to the allylic cation moiety and construction of a 1,2-dihydroquinoline. Our group also discovered that a regioselective hydroamidation of 2-(1-alkynyl

Synthesis of novel 5-alkyl/aryl/heteroaryl substituted diethyl 3,4-dihydro-2H-pyrrole-4,4-dicarboxylates by aziridine ring expansion of 2-[(aziridin-1-yl)-1-alkyl/aryl/heteroaryl-methylene]malonic acid diethyl esters

• Satish S. More,
• T. Krishna Mohan,
• Y. Sateesh Kumar,
• U. K. Syam Kumar and
• Navin B. Patel

Beilstein J. Org. Chem. 2011, 7, 831–838, doi:10.3762/bjoc.7.95

• ], pyrrolines [10][11][12][13][14], imidazolidinones [15], β-lactams [16][17][18] and azepines [19][20][21]. There is ample evidence in the literature to confirm that the syntheses and applications of the N-acyl, N-sulfonamide or N-benzyl protected C-vinylaziridines are of considerable interest in organic

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• and trapping of the carbocation by the sulfonamide. Subsequent intramolecular hydroamination gave the pyrrolidine products. 1.3 Oxiranes As an oxophilic Lewis acid, gold can activate epoxides towards the attack of nucleophiles. A good example is the AuCl3 catalyzed ring opening of aryl alkyl epoxide

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• yield (99%) and with high diastereoselectivity (dr > 96:4) by gold-catalyzed cycloisomerization of the N-allyl sulfonamide 70 (Scheme 28) [25]. The success of the gold-catalyzed cycloisomerization of cyclopropene-enes, proceeding with intramolecular cyclopropanation of the olefin, lies in the

• , underwent nucleophilic attack by the cyclopropene in a 5-exo-dig manner followed by ring-opening. A subsequent Friedel–Crafts cyclization allowed the formation of the indene subunit (Equation 1, Scheme 32). Sulfonamide 91 contains a 1,7-enyne subunit and its gold-catalyzed cycloisomerization delivered

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• yields (Scheme 9). However, in sumatriptan the indole product resulting from the Fischer synthesis can still react further which leads to the formation of by-products and significantly reduced yields. One way to minimise this was to protect the nitrogen of the sulfonamide group prior to indole formation

• and decarboxylation then affords sumatriptan [14]. All the reported methods for the synthesis of sumatriptan begin with the sulfonamide group already present on the aromatic ring and several routes are possible to introduce this functional group. The scalable route to the sulfonamides inevitably

• formaldehyde as by-products [15]. Another possible approach is based on the direct displacement of a benzylic chloride by sodium sulfite and subsequent sulfonamide formation as shown in Scheme 13 [16]. A more recent method utilises a palladium-catalysed Negishi coupling to access a diverse library of benzylic

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