Ugi post-condensation copper-triggered oxidative cascade towards pyrazoles

• Aurélie Dos Santos,
• Laurent El Kaim,
• Laurence Grimaud and
• Caroline Ronsseray

Beilstein J. Org. Chem. 2011, 7, 1310–1314, doi:10.3762/bjoc.7.153

• reactions [14][15][16][17][18][19][20][21][22][23], however, to the best of our knowledge, there is no report involving α-hydrazonocarboxylic acids. Hydrazone 1a was prepared through condensation of pyruvic acid with phenylhydrazine. Adding 1a to aqueous formaldehyde, allylamine and tert-butylisocyanide in

• these optimized conditions. Results are reported in Table 1. Surprisingly, the reaction appears to be only efficient with Ugi adducts prepared with formaldehyde as the carbonyl component (Table 1, entries 1–5). With other aldehydes and ketones, even if the Ugi reaction was performed easily, the

• reaction with N-alkyl hydrazones: An attempt of Ugi coupling with hydrazone 1d, formaldehyde, allylamine and tert-butylisocyanide failed to give any isolable adduct (Scheme 3). This may be explained by an enhanced nucleophilicity of the N-monoalkyl hydrazone leading to a competition between the hydrazone

Bromine–lithium exchange: An efficient tool in the modular construction of biaryl ligands

• Laurence Bonnafoux,
• Frédéric R. Leroux and
• Françoise Colobert

Beilstein J. Org. Chem. 2011, 7, 1278–1287, doi:10.3762/bjoc.7.148

• was used as an electrophile, 2-azido-2',6-dibromobiphenyl was obtained. The use of lithium aluminium hydride in ether at reflux for 4.5 h gave exclusively 2-amino-2',6-dibromobiphenyl, which was submitted to a reductive methylation by means of formaldehyde and sodium cyanoborohydride. 2-N,N

Lithium phosphonate umpolung catalysts: Do fluoro substituents increase the catalytic activity?

• Anca Gliga,
• Bernd Goldfuss and
• Jörg M. Neudörfl

Beilstein J. Org. Chem. 2011, 7, 1189–1197, doi:10.3762/bjoc.7.138

• ). The synthesis of diol 1 was conducted by an ortho lithiation of 1,1,1,3,3,3-hexafluoro-2-phenylpropan-2-ol and subsequent addition of the in situ generated carbanion to formaldehyde. For comparison, a nonfluorinated diol precursor 2 was synthesized. Diol 3 was used as the precursor to investigate the

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

• 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

• of the imidazole 162 also forms the dichlorination product 164 (as shown in Scheme 33) with formaldehyde as a by-product which proved difficult to suppress and made purification of the reaction mixture problematic. Hence, a sequence involving silyl protection, chlorination and deprotection was

• introduced via a Friedel–Crafts/Mannich-type alkylation starting either from formaldehyde and dimethylamine or 2,2-dimethoxy-N,N-dimethylacetamide (Scheme 45). In a recent study a more straightforward and general copper-catalysed three component coupling leading to imidazopyridines has been reported [69

The cross-metathesis of methyl oleate with cis-2-butene-1,4-diyl diacetate and the influence of protecting groups

• Arno Behr and
• Jessica Pérez Gomes

Beilstein J. Org. Chem. 2011, 7, 1–8, doi:10.3762/bjoc.7.1

• synthesised by the catalytic reaction of 1,3-butadiene with acetic acid on a large scale. The classical preparative method for 1,4-butanediol is the copper catalysed reaction of acetylene with formaldehyde and subsequent hydrogenation of the intermediate [23]. Currently, the symmetric acylated substrate 2 is

ROMP-Derived cyclooctene-based monolithic polymeric materials reinforced with inorganic nanoparticles for applications in tissue engineering

• Franziska Weichelt,
• Solvig Lenz,
• Stefanie Tiede,
• Ingrid Reinhardt,
• Bernhard Frerich and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, 1199–1205, doi:10.3762/bjoc.6.137

• third passage hATSC of three individuals were pooled for the experiment and seeded onto the discs at a density of 20,000 cells per cm². After 1, 2, 4, 8, 12 and 16 days of culture, the discs were harvested and fixed in 4 wt % formaldehyde in PBS (phophate buffered saline, Serva, Heidelberg, Germany) for

Intramolecular hydroxycarbene C–H-insertion: The curious case of (o-methoxyphenyl)hydroxycarbene

• Dennis Gerbig,
• David Ley,
• Hans Peter Reisenauer and
• Peter R. Schreiner

Beilstein J. Org. Chem. 2010, 6, 1061–1069, doi:10.3762/bjoc.6.121

• surprisingly, several hydroxycarbenes exhibit remarkable [1,2]H-tunneling under cryogenic conditions in solid noble gas matrices, even at temperatures as low as 11 K: Hydroxymethylene (1) [13] and phenylhydroxycarbene (3) [14] yield formaldehyde (2) and benzaldehyde (4), respectively, as a result of facile

Novel 2-(ω-phosphonooxy-2-oxaalkyl)acrylate monomers for self-etching self-priming one part adhesive

• Joachim E. Klee and
• Uwe Lehmann

Beilstein J. Org. Chem. 2010, 6, 766–772, doi:10.3762/bjoc.6.95

• acrylate and formaldehyde, and subsequent etherification of the obtained product with diols and phosphorylation using POCl3. The polymerization enthalpy of 2-(ω-phosphonooxy-2-oxaalkyl)acrylates 3 as measured by DSC ranges from −29 to −53 kJ·mol−1. The shear bond strength of adhesive compositions 4

• , comprising of phosphoric acid ester moieties, were synthesized via a three step synthesis via Baylis–Hillman reaction of ethyl acrylate and formaldehyde, and subsequent etherification of the obtained product with diols and phosphorylation using POCl3 (Scheme 1, Table 1). The double bonds in 3 are evident in

• -phosphonooxy-2-oxaalkyl)acrylate monomers 3 with phosphoric acid moieties and alkyl as well as oxyalkyl spacers were synthesized in three steps via Baylis–Hillman reaction of ethyl acrylate and formaldehyde, and subsequent etherification of the obtained product with diols and phosphorylation using POCl3. The

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

Comparison of zwitterionic N-alkylaminomethanesulfonic acids to related compounds in the Good buffer series

• Robert D. Long,
• Newton P. Hilliard Jr,
• Suneel A. Chhatre,
• Tatiana V. Timofeeva,
• Andrey A. Yakovenko,
• Daniel K. Dei and
• Enoch A. Mensah

Beilstein J. Org. Chem. 2010, 6, No. 31, doi:10.3762/bjoc.6.31

• were synthesized in aqueous solution by reaction of primary or secondary amines with formaldehyde/sodium hydrogensulfite addition compound. The pKa values of the ammonium ions of this series of compounds (compared to existing Good buffers) was found to correlate well with the length of the carbon chain

• approach previously reported in the literature for the specific synthesis of aminomethanesulfonates. In this approach amines are reacted with the product of addition of sodium hydrogensulfite to formaldehyde [9][10]. The sodium hydrogensulfite/formaldehyde addition product 7 (sodium hydroxymethanesulfonate

• solution titrimetry (min. 5 repetitions from low to high, then high to low pH) using standardized NaOH and HCl solutions. General synthetic procedure The compounds were prepared by dissolving 0.200 mol (26.8 g) of sodium hydrogensulfite-formaldehyde addition product in 250 mL deionized water in a 500 mL

A short synthesis of (±)-cherylline dimethyl ether

• Bhima Y. Kale,
• Ananta D. Shinde,
• Swapnil S. Sonar,
• Bapurao B. Shingate,
• Sanjeev Kumar,
• Samir Ghosh,
• Soodamani Venugopal and
• Murlidhar S. Shingare

Beilstein J. Org. Chem. 2009, 5, No. 80, doi:10.3762/bjoc.5.80

• moderate yield. Immediate reduction of the isocyanate 10 by lithium aluminium hydride in tetrahydrofuran gave N-methylamine 6 in 90% yield. The crude amine 6, on Pictet–Spengler reaction with formaldehyde in acetic acid, gave (±)-cherylline dimethyl ether [15] 5 in 45% yield. In short, we have devised a

• ). A mixture of 6 (2.0 g, 0.006 mol), formaldehyde (0.64 g, 0.007 mol) and acetic acid (5 mL) was stirred at 90 °C under nitrogen atmosphere for 2 h. After cooling to room temperature, the reaction mixture was basified using saturated NaHCO3 solution. This basified solution was extracted ethyl acetate

An expedient synthesis of 5-n-alkylresorcinols and novel 5-n-alkylresorcinol haptens

• Kirsti Parikka and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2009, 5, No. 22, doi:10.3762/bjoc.5.22

• preparation of stilbenes from benzyltriphenylphosphonium salts and aryl aldehydes [30][31] and also include reactions of stabilized ylids with aryl aldehydes or short alkyl chain alkanals [32][33][34][35][36] and the preparation of o- and p-nitrostyrenes from the highly reactive formaldehyde [37]. To provide

Synthesis of methylenebisamides using CC- or DCMT- activated DMSO

• Qiang Wang,
• Lili Sun,
• Yu Jiang and
• Chunbao Li

Beilstein J. Org. Chem. 2008, 4, No. 51, doi:10.3762/bjoc.4.51

• ], hexamethylenetetramine [21] or activated DMSO [6], or by the reaction of nitriles with formaldehyde [22] or activated sulfoxides [23]. However, each method has certain limitations with regards to scope and reaction conditions, for example, longer reaction time [20], lower yield [6], purification problems [21][23] and

Expedient syntheses of the N-heterocyclic carbene precursor imidazolium salts IPr·HCl, IMes·HCl and IXy·HCl

• Lukas Hintermann

Beilstein J. Org. Chem. 2007, 3, No. 22, doi:10.1186/1860-5397-3-22

• behind such differences of the reaction outcome? To our knowledge, the mechanism of the Arduengo imidazolium salt synthesis has not been discussed in the literature. We propose that alkylation of the DADs A by formaldehyde and HCl (or TMSCl) leads to an iminium salt B (Scheme 2); analogous alkylations

• (Scheme 3a). [21] This is one potential side-reaction, but brown colored side-products can also derive from electrophilic aromatic alkylations of arylamine units by iminium salts from formaldehyde or protonated DADs (as in the bakelite reaction). Such side-reactions will be most prominent with DADs from