Efficient electroorganic synthesis of 2,3,6,7,10,11-hexahydroxytriphenylene derivatives

• Carolin Regenbrecht and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2012, 8, 1721–1724, doi:10.3762/bjoc.8.196

• acidic hydrolysis. The electrolysis is conducted in propylene carbonate circumventing toxic and expensive acetonitrile. The protocol is simple to perform and superior to other chemical or electrochemical methods. The key of the method is based on the low solubility of the anodically trimerized product

• [11][12]. Furthermore, no transition metal cations, which promote the cleavage of the ketal moiety [11], are involved. The anodic oxidation of catechol derivatives was first demonstrated by Parker et al. [13]. Applying this methodology in a specific electrolysis cell, Simonet et al. established a

• trimerization protocol [14][15][16]. Usually, yields are in a moderate range (≤35%) [15] when the electrolysis is performed on platinum or graphite anodes in anhydrous and non-nucleophilic electrolytes [14]. Poor yields are caused by the low oxidation potential of the products and the preference for over

Electrochemical generation of 2,3-oxazolidinone glycosyl triflates as an intermediate for stereoselective glycosylation

• Toshiki Nokami,
• Akito Shibuya,
• Yoshihiro Saigusa,
• Shino Manabe,
• Yukishige Ito and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2012, 8, 456–460, doi:10.3762/bjoc.8.52

• often observed for pyranosides with a 2,3-trans carbamate group, under acidic conditions. The yield of disaccharide 8 was improved by raising the temperature to 0 °C after the completion of electrolysis at −78 °C (Table 3, entry 5). The fact that disaccharide 8 was obtained in higher yields (59% to 78

• %) and that only a trace amount of α-isomer 9 (4%) was obtained strongly suggests that the isomerization of thioglycoside donor 1a occurs during the electrolysis at 0 °C. It is noteworthy that the α- and β-glycosides could be selectively prepared from the same glycosyl donor with a 2,3-trans carbamate

• situ by the reaction of glycosyl triflate 2a with alcohols. Thus, TfOH (1.0 equiv) and tetrabutylammonium triflate (Bu4NOTf) (5.0 equiv), which was used as a supporting electrolyte for electrolysis, were added to a CH2Cl2 solution of the β-isomer of disaccharide 8β at 0 °C. After stirring at 0 °C for 1

Evaluation of a commercial packed bed flow hydrogenator for reaction screening, optimization, and synthesis

• Marian C. Bryan,
• David Wernick,
• Christopher D. Hein,
• James V. Petersen,
• John W. Eschelbach and
• Elizabeth M. Doherty

Beilstein J. Org. Chem. 2011, 7, 1141–1149, doi:10.3762/bjoc.7.132

• a convenient bench-top hydrogen flow reactor, the H-Cube®, designed for smaller-scale use in academic and drug discovery labs [6]. The reactor features a built-in hydrogen generator that functions by the electrolysis of water. Disposable pre-packed catalyst cartridges (CatCart®) are also available

A practical microreactor for electrochemistry in flow

• Kevin Watts,
• William Gattrell and
• Thomas Wirth

Beilstein J. Org. Chem. 2011, 7, 1108–1114, doi:10.3762/bjoc.7.127

• trapped immediately after generation. In the "cation flow" method, a carbocation is generated continuously in a flow system by low temperature electrolysis. The generation of the cation can be monitored by a FTIR spectrometer in the flow system. The electrochemically generated N-acyliminium ions can then

• conversion was achieved as established by GC/MS. The reaction shown in Scheme 2 has previously been performed in batch electrolysis leading to product 5 in 78% yield [17]. In addition, Kolbe-type reactions were investigated in flow. 2-Phenylacetic acid (6a) was used as a substrate and yields of up to 40% of

• the reduction of methanol at the cathode. The Kolbe electrolysis of 6a has also been described as a batch reaction, with a solid base, providing the product 7a in 44% yield [19]. This means that the reaction conditions in the electrochemical microreactor were comparable to batch synthesis. The

Prediction of reduction potentials from calculated electron affinities for metal-salen compounds

• Sarah B. Bateni,
• Kellie R. England,
• Anthony T. Galatti,
• Handeep Kaur,
• Victor A. Mendiola,
• Alexander R. Mitchell,
• Michael H. Vu,
• Benjamin F. Gherman and
• James A. Miranda

Beilstein J. Org. Chem. 2009, 5, No. 82, doi:10.3762/bjoc.5.82

• evidence for the formation of a Ni(II)-salen radical anion during electrolysis was later put forth by Peters and co-workers [6]. In mediated ERC, while Ni(II)-salen (reduction potential or Epc = −2.1 V vs. Ag/AgNO3) is an effective electrochemical mediator, the analogous Co(II)-salen (Epc = −1.6 V vs. Ag

Generation of pyridyl coordinated organosilicon cation pool by oxidative Si-Si bond dissociation

• Toshiki Nokami,
• Ryoji Soma,
• Yoshimasa Yamamoto,
• Toshiyuki Kamei,
• Kenichiro Itami and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2007, 3, No. 7, doi:10.1186/1860-5397-3-7

• organosilicon cation stabilized by intramolecular pyridyl coordination was effectively generated and accumulated by oxidative Si-Si bond dissociation of the corresponding disilane using low temperature electrolysis, and was characterized by NMR and CSI-MS. Findings We have recently developed the "cation pool