Chiral bifunctional sulfide-catalyzed enantioselective bromolactonizations of α- and β-substituted 5-hexenoic acids

• Sao Sumida,
• Ken Okuno,
• Taiki Mori,
• Yasuaki Furuya and
• Seiji Shirakawa

Beilstein J. Org. Chem. 2024, 20, 1794–1799, doi:10.3762/bjoc.20.158

• report provides a valuable example of catalytic enantioselective halolactonization of 5-hexenoic acid derivatives without extra substituents on the carbon–carbon double bond. Catalytic asymmetric halolactonizations of alkenoic acids. Effects of chiral sulfide catalysts. Effects of brominating reagents

Visible-light-induced bromoetherification of alkenols for the synthesis of β-bromotetrahydrofurans and -tetrahydropyrans

• Run Lin,
• Hongnan Sun,
• Chao Yang,
• Youdong Yang,
• Xinxin Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2015, 11, 31–36, doi:10.3762/bjoc.11.5

• . Keywords: alkenols; bromoetherification; photoredox catalysis; visible light; Introduction The halocyclization of alkenes provides an excellent synthetic method for halogenated heterocycles [1][2][3]. In recent years, haloaminocyclization [4][5], halolactonization [6][7] and haloetherification [8][9] of

Solvent-free phase-vanishing reactions with PTFE (Teflon^®) as a phase screen

• Kevin Pels and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2009, 5, No. 75, doi:10.3762/bjoc.5.75

• a very good yield (Table 3, entry 2). Bromination of 3-butenoic acid (21) gave the corresponding lactone 22 as the minor product while the dibromoacid 23 was the major product. We examined the possibility of tandem reactions with a solvent-free Diels-Alder/halolactonization reaction. Cyclopentadiene

• solvent-free PV-PTFE conditions. Bromination of phenol (13) under solvent-free PV-PTFE conditions. Halolactonization and tandem Diels-Alder/Halolactonization reactions under solvent-free PV-PTFE conditions. Supporting Information Supporting Information File 88: Additional experimental details and 1H NMR

Phase- vanishing halolactonization of neat substrates

• Nicole Windmon and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2008, 4, No. 29, doi:10.3762/bjoc.4.29

• triphasic reactions which involve a reagent, a liquid perfluoroalkane as a phase screen and a substrate. The perfluoroalkane does not dissolve any of the reactants and is used to separate them. Halolactonization of neat substrates under phase-vanishing conditions avoids use of both solvents and basic

• ; halocyclization; halolactonization; iodine monochloride; phase-vanishing reactions; Introduction Phase-vanishing reactions, introduced by Ryu [1], Curran [1][2] and Verkade [3], are triphasic reactions, which involve a reagent, a substrate and a liquid perfluoroalkane. A more recent improvement of phase

• would occur if the two reactants were mixed without a phase screen. In the course of the reaction, the reagent disappears (“vanishes”) and the product is mechanically separated from perfluoroalkane, which can be reused. Halolactonization and halocyclizations are important reactions in organic synthesis