A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• -symmetric I(III) reagent 8b was used to obtain high enantioselectivity. Ishihara et al. appealingly reported an oxidative cycloetherification of ketophenols 92 in the presence of an in situ generated chiral quaternary ammonium (hypo)iodite salt 94, with hydrogen peroxide as an oxidant to deliver chiral

Synthesis of substituted Z-styrenes by Hiyama-type coupling of oxasilacycloalkenes: application to the synthesis of a 1-benzoxocane

• James R. Vyvyan,
• Courtney A. Engles,
• Scott L. Bray,
• Erik D. Wold,
• Christopher L. Porter and
• Mikhail O. Konev

Beilstein J. Org. Chem. 2017, 13, 2122–2127, doi:10.3762/bjoc.13.209

• the eight-membered ring. We endeavored to test the strategy through the preparation of a simplified model compound 1 (Figure 1). We envisaged the precursor to the cycloetherification, 2, would be prepared from the Hiyama-type cross-coupling of the appropriate aryl iodide 3 and the oxasilacycloalkene 4

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• cycloetherification reactions based on the use of in situ-generated chiral quaternary ammonium hypoiodite species. By using Maruoka-type catalysts B, which contain an iodide counter anion, in the presence of a simple oxidant like H2O2 they were able to generate a chiral hypoiodite species in situ, which then

• facilitates the asymmetric intramolecular cycloetherification of starting materials 27 (Scheme 13). One of the important observations in this impressive report was the necessity of the imidazole moiety to achieve high selectivities [125]. In a subsequent study, the same group also expanded this concept to 6

• dearomatization of phenols and naphthols. Ishihara’s ammonium salt-catalysed oxidative cycloetherification. Chiral phase-transfer-catalysed α-sulfanylation reactions. Chiral phase-transfer-catalysed α-trifluoromethylthiolation of β-ketoesters 1. Chiral phase-transfer-catalysed α-amination of β-ketoesters 1 using

C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• –X containing compounds. Recently, Zhu and co-workers reported a new approach for the synthesis of 2 or 4-iododibenzofurans based on CuI-mediated cascade reactions wherein the C–H iodination and cycloetherification acted as key transformations [55]. As outlined in Scheme 15, in the presence of 1.5

Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds

• Miroslav Palík,
• Jozef Kožíšek,
• Peter Koóš and
• Tibor Gracza

Beilstein J. Org. Chem. 2014, 10, 2077–2086, doi:10.3762/bjoc.10.216

• [2.2.1]heptane and 2,6-dioxabicyclo[3.2.1]octane, respectively. Such bicyclic ring subunits are found in many natural products including ocellenynes and aurovertines. Keywords: alkenols; cycloetherification; homogeneous catalysis; natural products; palladium; Introduction Oxaheterocycles of various

Gold-catalyzed heterocyclizations in alkynyl- and allenyl-β-lactams

• Benito Alcaide and
• Pedro Almendros

Beilstein J. Org. Chem. 2011, 7, 622–630, doi:10.3762/bjoc.7.73

• AuCl3 could be a good catalyst for the cycloetherification reaction of non-terminal alkynols 22. Scheme 12 shows that tetrahydrofuryl hemiacetals 23 are accessible as single isomers in fair yields via the gold-catalyzed tandem oxycyclization/hydroxylation reaction of 2-azetidinone-tethered

• scope of these transformations, gold-catalyzed heterocyclization reactions of alkynols to the fused bicyclic systems was also examined. Indeed, treatment of 2-azetidinone-tethered bishomopropargylic alcohol 26 with AuCl3 provided the desired cycloetherification/hydroxylation product 27a in good yield

Carbasugar analogues of galactofuranosides: α-O-linked derivatives

• Jens Frigell and
• Ian Cumpstey

Beilstein J. Org. Chem. 2010, 6, 1127–1131, doi:10.3762/bjoc.6.129

• structure 14, but not in 14x. Hence, compound 13 presumably arose from debenzylative cycloetherification by attack of O-6 on C1, C1 being the most electrophilic carbon in both inter- and intramolecular epoxide-opening reactions. To achieve the inversion of stereochemistry at C2 of the α-talo carbasugars