Highly brominated anthracenes as precursors for the convenient synthesis of 2,9,10-trisubstituted anthracene derivatives

• Osman Cakmak,
• Leyla Aydogan,
• Kiymet Berkil,
• Ilhami Gulcin and
• Orhan Buyukgungor

Beilstein J. Org. Chem. 2008, 4, No. 50, doi:10.3762/bjoc.4.50

• tribromide 12 was transformed to trimethoxy compound 13 and trinitrile 14 by copper-assisted nucleophilic substitution reactions. Keywords: anthracene derivative; bromination; bromoanthracene; cyanoanthracene; methoxyanthracene; Introduction Anthracene derivatives have been extensively investigated in many

Understanding the mechanism of Pd-catalyzed allylic substitution of the cyclic difluorinated carbonates

• Jun Xu,
• Xiao-Long Qiu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2008, 4, No. 18, doi:10.3762/bjoc.4.18

• Pd-catalyzed allylic substitution reactions. X-ray structure of trans-trans dimer 8. Pd-catalyzed allylic substitution of the gem-difluorinated allylic carbonates 1 and 4. Synthesis of trans-trans dimer 8 and syn-syn dimer 9. Reaction of trans-trans dimer 8 with 3-benzoylthymine sodium / PPh3

Synthesis of the Benzo- fused Indolizidine Alkaloid Mimics

• Daniel L. Comins and
• Kazuhiro Higuchi

Beilstein J. Org. Chem. 2007, 3, No. 42, doi:10.1186/1860-5397-3-42

• indolizidine alkaloid mimics has been developed. The indolizidine derivatives 8 were prepared via heteroaryl Grignard addition to N-acylpyridinium salts followed by an intramolecular Heck cyclization. Further substitution reactions were developed to demonstrate that heterocycles 8 are good scaffolds for

Single and double stereoselective fluorination of (E)-allylsilanes

• Marcin Sawicki,
• Angela Kwok,
• Matthew Tredwell and
• Véronique Gouverneur

Beilstein J. Org. Chem. 2007, 3, No. 34, doi:10.1186/1860-5397-3-34

• ). When a second stereogenic centre is present on the starting (E)-allylsilane, up to four stereoisomers may be formed upon fluorination. This is illustrated in Scheme 1 with the fluorodesilylation of anti (E)-1e. For substitution reactions (SE2') of allylsilanes such as anti (E)-1e, with electrophiles

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

• them from participating as electrophiles in aromatic substitution reactions. Conclusion The useful imidazolium salts IPr·HCl (1), IMes·HCl (2) and IXy·HCl (3) have previously been synthesized by a range of methods giving the products in variable purity and yields. We now present a protocol for the

Pd-catalysed [3 + 3] annelations in the stereoselective synthesis of indolizidines

• Olivier Y. Provoost,
• Andrew J. Hazelwood and
• Joseph P. A. Harrity

Beilstein J. Org. Chem. 2007, 3, No. 8, doi:10.1186/1860-5397-3-8

• reasons for this difference in catalyst activity are unclear at present, we speculate that n-BuLi may be responsible for the formation of hitherto uncharacterised phosphine ligands BunP(OiPr)3-n that promote the annelation over simple P(OiPr)3. Indeed, analogous alkoxide substitution reactions of

Efficient synthesis of 5-substituted 2-aryl- 6-cyanoindolizines via nucleophilic substitution reactions

• Eugene V. Babaev,
• Natalya I. Vasilevich and
• Anna S. Ivushkina

Beilstein J. Org. Chem. 2005, 1, No. 9, doi:10.1186/1860-5397-1-9

• – 8.11 ppm. The halogen atom in 5-chloro-6-cyanoindolizines 2 should be activated to nucleophilic substitution reactions by the suitable ortho-arrangement of the nitrogen atom of the pyridine ring and electron-withdrawing cyano-group. The pattern strongly resembled 2-chloro-3-cyanopyridine, that is why

• obtain 2-aryl-5-chloro-6-cyano-7-methylindolizines from 2-aryl-6-cyano-7-methyl-5-indolizinones and to prove the possibility to employ them in nucleophilic substitution reactions. Moreover, these reactions are the first examples of preparative nucleophilic substitution in indolizines, and our findings