Beilstein J. Org. Chem.2015,11, 31–36, doi:10.3762/bjoc.11.5
photoredox-catalyzed bromoetherification of alkenols is described. This approach, with CBr4 as the bromine source through generation of bromine in situ, provides a mild and operationally simple access to the synthesis of β-bromotetrahydrofurans and -tetrahydropyrans with high efficiency and regioselectivity
.
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
investigations on the photoredox catalytic reactions [16][23][24][25][26][27], herein we report our preliminary studies on visible-light-induced photoredox-catalyzed bromoetherification of alkenols using CBr4 as the bromine source.
Results and Discussion
Our initial studies were focused on the reaction of
PDF
Graphical Abstract
Scheme 1:
Control experiment with liquid bromine for bromoethrification of alkenols.
Beilstein J. Org. Chem.2013,9, 655–663, doi:10.3762/bjoc.9.74
of vinylmagnesium bromide [16], provided 9. The bromoetherification of tertiary alcohol 9 by using NBS led to tetrahydrofuran 10 as a diastereomeric mixture. Next, the base-induced elimination of HBr converted 10 to diene 11, which underwent the Claisen rearrangement at 170 °C to give rise to
PDF
Graphical Abstract
Scheme 1:
Structure of ryanodine and the Diels–Alder reactions for construction of the potential intermediate...