Convenient methods for preparing π-conjugated linkers as building blocks for modular chemistry

• Jiří Kulhánek,
• Filip Bureš and
• Miroslav Ludwig

Beilstein J. Org. Chem. 2009, 5, No. 11, doi:10.3762/bjoc.5.11

• easily accessible as a pure (E)-product from the pinacol ester of 4-formylphenylboronic acid and diethyl benzylphosphonate through the Horner–Wadsworth–Emmons reaction in 76% yield [36], methoxy and N,N-dimethylamino substituted (E)-4-bromostilbenes were synthesized from the corresponding benzaldehydes

• and 4-bromobenzyl(triphenyl)phosphonium bromide [37] by the Wittig reaction [37][38] in 37 and 54% yields, respectively. In contrast to the Horner–Wadsworth–Emmons reaction, this procedure afforded both (E)- and (Z)-stilbenes that were isomerized by heating with traces of iodine in toluene to afford

• the Horner–Wadsworth–Emmons reaction described above. These substituted 4-bromostilbenes could be most effectively converted to target pinacol esters 5a–c via borylation (Scheme 1, Method C) utilizing bis(pinacolato)diboron (pin2B2) [39] in a mixed solvent system DMSO/dioxane ensuring good solubility

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

Combining two-directional synthesis and tandem reactions, part 11: second generation syntheses of (±)-hippodamine and (±)-epi-hippodamine

• Annabella F. Newton,
• Martin Rejzek,
• Marie-Lyne Alcaraz and
• Robert A. Stockman

Beilstein J. Org. Chem. 2008, 4, No. 4, doi:10.1186/1860-5397-4-4

• sensitive dialdehyde 5 . Whilst we were able to purify compound 5, this resulted in a significant loss of material through degradation of the dialdehyde on the purification media, be it silica gel or neutral alumina. Thus, we found that use of the crude dialdehyde in the subsequent Horner-Wadsworth-Emmons

New modification of the Perkow reaction: halocarboxylate anions as leaving groups in 3-acyloxyquinoline- 2,4(1H,3H)-dione compounds

• Oldřich Paleta,
• Karel Pomeisl,
• Stanislav Kafka,
• Antonín Klásek and
• Vladislav Kubelka

Beilstein J. Org. Chem. 2005, 1, No. 17, doi:10.1186/1860-5397-1-17

• the corresponding 4-ethoxyquinolin-2(1H)-one. In both reactions, the fluorocarboxylate anion acts as the first observed leaving group. This observation restricts the application of the intramolecular Horner-Wadsworth-Emmons synthesis to modify quinoline-2,4(1H,3H)-diones by the annulation of

• annulation of the fluorobutenolide cycle. An analogous Horner-Wadsworth-Emmons synthesis using ethyl (diethoxyphosphoryl)-fluoroacetate prepared from ethyl fluoroiodoacetate has been reported for the preparation of the α-fluoro-α,β-unsaturated acyclic esters and lactones. [14] However, when 1-benzyl-3-butyl

• -3-(fluoroiodoacetoxy)quinoline-2,4(1H,3H)-dione (4) was reacted with triethyl phosphite an unexpected product 9 (Scheme 3) was obtained instead of the desired Horner-Wadsworth-Emmons intermediate 1-benzyl-3-butyl-3-(diethoxyphosphoryl)fluoroacetyloxy-quinoline-2,4(1H,3H)-dione. We assume the newly