Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• polymerized via various heterophase polymerizations, including polymerization in miniemulsion. The first report on polymerization of ethylene in miniemulsion describes the synthesis of polyethylene nanoparticles in the presence of a nickel–ylide complex [10]. The catalyst was dissolved in toluene and

• ethylene and up to 3 mol % 1-butene. Small nanoparticles (~200 nm) could be obtained by ethylene polymerization with a nickel(II) keto–ylide complex with 10% solids content in direct miniemulsion [63]. The same group copolymerized ethylene and polar and non-polar α-olefins in miniemulsion with a P,O

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

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

• used in the total synthesis of mucocin (Scheme 21) [65]. The ylide 149, which was synthesized from the cis-THF alcohol 148a, was coupled with the butenolide aldehyde 150 via a Wittig reaction to afford the THF aldehyde 151 after further 3 steps. Then addition of the magnesium derivative of iodide 152

• Swern oxidation, and then reaction of the resulting aldehyde with CH3(CH2)13MgCl gave the bis-THF segment 250. The coupling reaction between the aldehyde prepared from 250 and the ylide prepared from 47 gave the enyne 251, which was hydrogenated. Global deprotection allowed completion of the synthesis

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

• can be induced by chloromethylethers. Loss of HCl from B (presumably to A, which is a monobasic species)[13] gives an imino-azomethin-ylide 1,5-dipole C (only one mesomeric structure shown), which will undergo 1,5-dipolar cyclization (6π electrocyclization) [18][19][20] to an oxy-imidazoline D

Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes

• Stephen P. Marsden and
• Pascal C. Ducept

Beilstein J. Org. Chem. 2005, 1, No. 5, doi:10.1186/1860-5397-1-5

• )ketenes were used as substrates.[16][17] Thus, only 3-substituted and 3,3-disubstituted allenylsilanes have thus far been accessed by alkylidenation of silylketenes, whilst no reports of the successful introduction of non-stabilised ylide equivalents have been forthcoming. A second impediment to the

• yield, Scheme 2, Table 2. As expected, reactions with the more substituted ylide 4 were significantly slower than those with the parent ylide 5 (compare reaction temperatures and times, entries 1, 3 and 5 versus entries 2, 4 and 6). Increasing the steric bulk of the ketene substituent also slows the

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

• transformations.[1] Indeed, near perfect levels of asymmetric induction with high diastereocontrol have been achieved with aromatic aldehydes (Scheme 1). In such reactions, the C1 stereochemistry is controlled by ylide conformation, face selectivity, and the degree of reversibility in formation of the anti

• clearly shown by sulfide 2 could be exploited in reactions with chiral aldehydes and to what extent it might dominate over substrate control (Scheme 2).[3] Again C1 stereochemistry should be controlled by ylide conformation, face selectivity, degree of reversibility in anti betaine formation, and is not

• (dimethylamino)-phosphoranylidene]-phosphoric triamide ethylimine,) [4][5] (sulfur ylide 4) was initially investigated to establish the degree of substrate control. This furnished a mixture of 3 epoxides 7a, 7b, and 7c in a 37:14:49 ratio (Table 1, entry 1). The cis and trans isomers are easily distinguished by