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

• approximately equal yield. In entry (iii) of that table, these yields were estimated from a calibrated NMR determination; following this, the mixture was subjected to epoxidation with mCPBA, leading to isolation of 20b and the epoxide 20c (not shown in Scheme 3) derived from 20a. From this series of experiments

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• materials (e.g. amino acids, sugars, tartaric acid, etc.) or on asymmetric reactions {e.g. Sharpless asymmetric epoxidation (AE), Sharpless asymmetric dihydroxylation (AD), diastereoselective Williamson etherification, etc.}. Semi-synthesis of natural ACGs as well as derivatised ACGs (e.g. amines, esters

• absolute configuration of natural-8 at C-8 to R (Scheme 3). In their synthesis, asymmetric epoxidation of 19 directed by L-(+)-diisopropyl tartrate gave epoxy alcohol 20; the THF ring of 21 was then constructed under CSA catalyzed one-pot transformation. After deprotection of the isopropylidene acetal of

• building block 45 by means of the Sharpless AD reaction and cyclization catalyzed by Co(modp)2 (the Mukaiyama epoxidation method) under mild reaction conditions. The connection of the THF unit 46 with the γ-lactone segment 47 was carried out by means of a Wittig reaction. The target compound 42 had

End game strategies towards the total synthesis of vibsanin E, 3-hydroxyvibsanin E, furanovibsanin A, and 3-O-methylfuranovibsanin A

• Brett D. Schwartz,
• Craig M. Williams and
• Paul V. Bernhardt

Beilstein J. Org. Chem. 2008, 4, No. 34, doi:10.3762/bjoc.4.34

• procedure based on the epoxidation of silyl enol ethers. Ketone 23 was smoothly converted into the TBS enol ether 27 (85% yield) with TBS triflate, which was then treated with dimethyldioxirane (DMDO). When work up was restricted to a simple 1 M hydrochloric acid wash (i.e. separatory funnel) only the

Allylsilanes in the synthesis of three to seven membered rings: the silylcuprate strategy

• Asunción Barbero,
• Francisco J. Pulido and
• M. Carmen Sañudo

Beilstein J. Org. Chem. 2007, 3, No. 16, doi:10.1186/1860-5397-3-16

• groups in appropriate positions undergo silylcupration-ring formation, when treated with higher order cyanocuprates as (PhMe2Si)2CuCNLi2. Intramolecular trapping of the vinylcuprate intermediate allows the synthesis of methylenecyclopentanes 20–22 (Scheme 4). [14] Epoxidation of the oxoallylsilanes

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

• selectivity leading to exclusive formation of 12. In a similar fashion, and in agreement with the idea of two directing groups working in concert, epoxidation of the exo derived diene 5 afforded exclusive formation of epoxide 13. Speculating that disruption of any directing effects through the use of more

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• aminocyclitols it could be an epoxidation followed by the nucleophilic opening of the epoxide moiety by a primary amine or another nitrogen nucleophile. Accordingly (Scheme 1), treatment of the fully O-protected L-ido-cyclooctene 1 with a 5 mol% aqueous solution of osmium(IV) tetroxide [34] in acetone in the

• epoxidation [35] of the cyclooctenes 1 and 2 (Scheme 2). Thus, treatment of 1 and 2 with meta-chloroperbenzoic acid in the presence of sodium hydrogen carbonate afforded the epoxides 7 and 8 in 91–96% yield. As precedently, because of the C2-axis of symmetry displayed by the L-ido or D-manno-cyclooctenes 1

Reagent controlled addition of chiral sulfur ylides to chiral aldehydes

• Varinder K. Aggarwal and
• Jie Bi

Beilstein J. Org. Chem. 2005, 1, No. 4, doi:10.1186/1860-5397-1-4

• respects it is surprising that the subtle effect of stereochemistry of the aldehyde has such a significant impact on the bond rotation step and therefore reversibility of betaine formation. Epoxidation of (+)-Glyceraldehyde with Sulfur Ylides Supporting Information Supporting Information File 28