N,N'-(Hexane-1,6-diyl)bis(4-methyl-N-(oxiran-2-ylmethyl)benzenesulfonamide): Synthesis via cyclodextrin mediated N-alkylation in aqueous solution and further Prilezhaev epoxidation

• Julian Fischer,
• Simon Millan and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2834–2840, doi:10.3762/bjoc.9.318

• bonded hydroxy stretching vibrations originating from epoxide ring opening. The epoxide bands seem to vanish after curing, which is a sign for high conversion. However, due to overlaps of broader bands in adjacent areas, no clear statement can be made in this regard (Figure S5, Supporting Information

A protecting group-free synthesis of the Colorado potato beetle pheromone

• Zhongtao Wu,
• Manuel Jäger,
• Jeffrey Buter and
• Adriaan J. Minnaard

Beilstein J. Org. Chem. 2013, 9, 2374–2377, doi:10.3762/bjoc.9.273

• efficient synthesis of the aggregation pheromone of the Colorado potato beetle (S)-1,3-dihydroxy-3,7-dimethyl-6-octen-2-one (1). Combining Sharpless asymmetric epoxidation, stereoselective epoxide ring-opening and catalytic chemoselective alcohol oxidation with [(neocuproine)PdOAc]2OTf2 (2), (S)-1 was

Synthesis of the calcilytic ligand NPS 2143

• Henrik Johansson,
• Thomas Cailly,
• Alex Rojas Bie Thomsen,
• Hans Bräuner-Osborne and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 1383–1387, doi:10.3762/bjoc.9.154

• . Similar to a previously reported synthesis of (R)-3 [13], we decided to activate epoxide 5 as the m-nosyl derivative that has been shown to minimise racemisation during epoxide ring opening [15]. The synthesis of amine 6 was accomplished from commercially available 2-cyanonaphthalene (7) in four steps

Chemoenzymatic synthesis and biological evaluation of enantiomerically enriched 1-(β-hydroxypropyl)imidazolium- and triazolium-based ionic liquids

• Paweł Borowiecki,
• Małgorzata Milner-Krawczyk and
• Jan Plenkiewicz

Beilstein J. Org. Chem. 2013, 9, 516–525, doi:10.3762/bjoc.9.56

• oxide (1) under solvent-free conditions. The epoxide ring-opening reactions were carried for 24 h at elevated temperature (32 °C) and resulted in the formation of the appropriate alcohols (±)-3a and (±)-3b in high yields (Scheme 1). In the next step, the influence of crucial parameters in enzyme

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

• in the presence of catalytic amounts of gold and an external nucleophile such as water or an alcohol (Scheme 11) [32]. The reaction seems to commence with the epoxide ring opening in the presence of the nucleophile to give intermediate 33 (as already proposed in Scheme 9) followed by activation of

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• products 16 with complete inversion of configuration [16][17]. Acid catalysed cleavage of a thioether or thioacetate yields tert-thiols 17 in good yield. 1.1.2 Epoxide ring opening SN2 displacements from quaternary electrophiles require specific structural features to avoid competing racemisation

• epoxide ring opening of 18 with potassium hydrogen sulfide (Scheme 7) [18]. Epoxide ring opening by a sulfur nucleophile was also employed as the key step in the synthesis of (+)-BE-52440A (22) [22] (Scheme 8). Dimerisation of nanaomycin derivative 21 through a bridging sulfide involves a double

Carbasugar analogues of galactofuranosides: α-O-linked derivatives

• Jens Frigell and
• Ian Cumpstey

Beilstein J. Org. Chem. 2010, 6, 1127–1131, doi:10.3762/bjoc.6.129

• isolated in a pure state. The pseudodisaccharide ketone 16 was also then reduced with L-selectride, again very good diastereoselectivity for the α-galacto configured carbasugar 18 was observed. Conclusion Complementing our approach to β-configured O-linked galactofuranosides by epoxide ring opening, the

• ; the difference in efficiency of the “up” (β-manno) and “down” (α-gluco) carbapyranose 1,2-epoxides in coupling reactions was not observed in the carbafuranose series. It is possible that this strategy for pseudodisaccharide formation by epoxide ring opening in the (α and β) carbagalactofuranose series

Synthesis and crystallographic analysis of meso-2,3-difluoro-1,4-butanediol and meso-1,4-dibenzyloxy-2,3-difluorobutane

• Bruno Linclau,
• Leo Leung,
• Jean Nonnenmacher and
• Graham Tizzard

Beilstein J. Org. Chem. 2010, 6, No. 62, doi:10.3762/bjoc.6.62

• (Table 1, entry 1), however, the product was isolated as a mixture of isomers, which were not further characterised. Reaction with potassium hydrogen difluoride in ethylene glycol [36][37] gave the fluorohydrin in only modest yield (entry 2). Interestingly, the product arising from epoxide ring opening

Prins fluorination cyclisations: Preparation of 4-fluoro-pyran and -piperidine heterocycles

• Guillaume G. Launay,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2010, 6, No. 41, doi:10.3762/bjoc.6.41

• incorporated into the product generating a C–F bond and a new stereogenic centre. Liberation of fluoride ion from BF3·OEt2 has, for example, been observed in epoxide ring opening reactions [8][9]. This was first recognised in a Prins reaction as an unexpected side reaction by Al-Mutairi et al. [10][11] and was

Three step synthesis of single diastereoisomers of the vicinal trifluoro motif

• Vincent A. Brunet,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2009, 5, No. 61, doi:10.3762/bjoc.5.61

• manner. Conversion of the free hydroxyl group to fluorine would generate α-fluoro-epoxides B. Epoxide ring opening with an HF source could then provide difluoroalcohols C. Insertion of the third fluorine would reasonably be achieved by fluorination of the free hydroxyl group of C to generate D. Such a

• the anti-isomers 6b and 7b was attempted using Deoxo-Fluor® [17]. α,β-Epoxy-alcohol 7b reacted smoothly with Deoxo-Fluor® at 40 °C (Scheme 4) to give fluoroepoxide (2S,3S,4R)-8b in 83% yield and with a 97:3 dr. Epoxide ring opening of 8b was then explored with HF/pyridine and this reaction proved to

• be both regio- and stereo-selective [18][19]. When the reaction was carried out at 0 °C the resultant difluoro alcohol 10 was obtained in 36% yield, whereas the yield improved as the temperature was lowered (47% at −35 °C and 56% at −60 °C). Epoxide ring opening was stereospecific, and the (2S,3S,4S

Photosonochemical catalytic ring opening of α-epoxyketones

• Hamid R. Memarian and
• Ali Saffar-Teluri

Beilstein J. Org. Chem. 2007, 3, No. 2, doi:10.1186/1860-5397-3-2

• epoxide ring opening. On the other hand, ultrasound can seriously affect photocatalytic ring opening of α-epoxyketones predominantly because of the efficient mass transfer of the reactants and the excited state of NBTPT. The higher yields and shorter reaction times are advantages of this method

The oxanorbornene approach to 3-hydroxy, 3,4-dihydroxy and 3,4,5-trihydroxy derivatives of 2-aminocyclohexanecarboxylic acid

• Ishmael B. Masesane,
• Andrei S. Batsanov,
• Judith A. K. Howard,
• Raju Mondal and
• Patrick G. Steel

Beilstein J. Org. Chem. 2006, 2, No. 9, doi:10.1186/1860-5397-2-9

• overcome the directing influence of the carbamate and deliver the epoxide to the opposite face of diene 5. Similarly, whilst the alternative regiochemistry in the epoxide ring opening product could be achieved exploiting neighbouring group participation by the NBoc group to afford the cyclic carbamate 29