Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• oxycarbenium ion, which enables high enantioselectivities up to 95% ee and yields up to 91%. Furthermore, an investigation of the involved halide counter-anion revealed that chloride was the most potent one in regards of both yield and enantioinduction. Bromine and iodine on the other hand, afforded the final

Carbonylonium ions: the onium ions of the carbonyl group

• Daniel Blanco-Ania and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2018, 14, 2568–2571, doi:10.3762/bjoc.14.233

• aldehyde- and ketone-based intermediates, respectively. Keywords: carboxonium ion; glycosylium ion; oxacarbenium ion; oxocarbenium ion; oxycarbenium ion; Introduction There is much confusion in the literature over the name of the intermediates R1C(=O+R3)R2 (R1, R2, R3 = H or organyl [1], 1; Figure 1). In

• group with mercury to a double bond. “Oxycarbenium ion” can also be found in the literature with this meaning that it correctly describes the same intermediate, although not the more realistic representation of it [30]. Carboxonium ions Other research groups, e.g., Olah’s and Prakash’s, have used the

• for this term [23][28]. Not only is the term “oxocarbenium ion” not suitable for describing intermediate 1, but also it is used to name another intermediate more accurately. Oxycarbenium ions Thirdly, another term that presents confusion because it is used for different intermediates is “oxycarbenium

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• fragmentation to produce radical 132. The radical 132 could be trapped with iodine, giving iodide 133. The oxycarbenium ion 134 generated by the extrusion of iodide from 133 reacted with the acetoxy ion to furnish the resulting acetate derivatives. The acetates 130 and 131 were then treated with silylated

• thymine or N4-benzoylcytosine in the presence of a Lewis acid to give the desired acyclic nucleosides 135 and 136 in excellent yields. The results revealed that the nucleophilic attack of the nucleobase selectively occurred from the less hindered side of the oxycarbenium ion intermediates, giving 1’,2

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• nucleosidation (Scheme 32) [86]. In this procedure an O-silylated pyrimidone (3.9) is combined with the acylated or benzoylated ribose derivative 3.10 in the presence of a strong Lewis acid. The generation of the reactive oxycarbenium ion as well as the liberated nucleophilic pyrimidone therefore occurs in situ