Continuous flow based catch and release protocol for the synthesis of α-ketoesters

• Alessandro Palmieri,
• Steven V. Ley,
• Anastasios Polyzos,
• Mark Ladlow and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2009, 5, No. 23, doi:10.3762/bjoc.5.23

• important products in their own right [82][83][84][85][86][87][88]. Common methods for the preparation of α-ketoesters include the modified Dakin-West reaction [89] and the addition of a Grignard reagent to oxalates or oxalyl chlorides [90][91][92] together with a few alternative syntheses [93][94][95][96

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

• by oxidation gave the aldehyde 191, which could readily be converted into the aldehyde 192. The bromide 193 was transformed into the corresponding Grignard reagent, which was allowed to react with the aldehyde 192 to afford the two epimers 194 and 195. The dianion of 196 was allowed to react with (S

Synthesis of densely functionalized enantiopure indolizidines by ring- closing metathesis (RCM) of hydroxylamines from carbohydrate- derived nitrones

• Marco Bonanni,
• Marco Marradi,
• Francesca Cardona,
• Stefano Cicchi and
• Andrea Goti

Beilstein J. Org. Chem. 2007, 3, No. 44, doi:10.1186/1860-5397-3-44

• the addition of organometallic reagents. [21][22] Recently, we developed a general protocol for the synthesis of α,α'-disubstituted enantiopure hydroxylamines 1 through the stereoselective double addition of an excess of a Grignard reagent to C-phenyl-N-erythrosylnitrone 2 (Scheme 1).[23] With this

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

• -acyldihydropyridones 1a-c in good yields (entries 1–3). In addition, the N-methyl-2-indolyl [11] Grignard reagent gave 1d in moderate yield (entry 4). In spite of trying various methods of preparing the 2-pyridyl [12][13][14][15] Grignard reagent, 1e was obtained in only 15% yield (entry 5). Encouraged by these

A divergent asymmetric approach to aza-spiropyran derivative and (1S,8aR)-1-hydroxyindolizidine

• Jian-Feng Zheng,
• Wen Chen,
• Su-Yu Huang,
• Jian-Liang Ye and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2007, 3, No. 41, doi:10.1186/1860-5397-3-41

• the reaction of functionalized Grignard reagent with protected (S)-malimide, either aza-spiropyran or (1S,8aR)-1-hydroxyindolizidine skeleton could be constructed in a concise and selective manner. The results presented herein constitute an important extension of our malimide-based synthetic

• stereoselectively to either hydroxylactams F or G under appropriate conditions. [36][37][38] It was envisioned that if a C4-bifunctional Grignard reagent was used, both aza-spiroketal H (such as aza-spiropyran, n = 1, path a) and indolizidine ring systems I (path b) could be obtained. The synthesis of aza

• of the O-benzyl group in K is an assumption based on our previous observation on a similar case.[42] Conclusion In summary, we have demonstrated that by the reaction of functionalized Grignard reagent with the protected (S)-malimide 4, either aza-spiropyran derivative 7 or (1S,8aR)-1

Development of potential manufacturing routes for substituted thiophenes – Preparation of halogenated 2-thiophenecarboxylic acid derivatives as building blocks for a new family of 2,6-dihaloaryl 1,2,4-triazole insecticides

• John W. Hull Jr.,
• Duane R. Romer,
• David E. Podhorez,
• Mezzie L. Ash and
• Christine H. Brady

Beilstein J. Org. Chem. 2007, 3, No. 23, doi:10.1186/1860-5397-3-23

• -methylthiophene 11 in a 64% yield. [10] This reaction has also been reported using aqueous bromine. [11] The carboxyl functionality was then introduced by formation of the 2-thienyl Grignard reagent [8][9][10][11] followed by treatment with dimethylcarbonate (DMC) to give ester 12a. Alternatively, a palladium

The use of silicon- based tethers for the Pauson- Khand reaction

• Adrian P. Dobbs,
• Ian J. Miller and
• Saša Martinović

Beilstein J. Org. Chem. 2007, 3, No. 21, doi:10.1186/1860-5397-3-21

• procedure was developed, initially adding the allyl arm via the allyl Grignard reagent, followed by a more standard silyl ether formation using an acetylenic alcohol and imidazole (without isolating the intermediate silyl chloride). (Isolation of the intermediate diisopropylallylsilyl chloride was