TY  - JOUR
A1  - Bramborg, Andrea
A1  - Linker, Torsten
T1  - Selective synthesis of 1,4-dialkylbenzenes from terephthalic acid
N2  - Terephthalic acid reacts with alkyl halides under Birch conditions to substituted 1,4-cyclohexadienes in high yields and good stereoselectivities. Electrophiles containing ester or nitrile groups undergo a surprising fragmentation under the reaction conditions. Subsequent treatment with chlorosulfonic acid proceeds by an interesting tandem decarbonylation/decarboxylation, affording 1,4-dialkylbenzenes in excellent regioselectivity. Thus our new method is superior to classical Friedel-Crafts alkylations.
Y1  - 2010
UR  - http://www3.interscience.wiley.com/cgi-bin/jhome/77002176
U6  - https://doi.org/10.1002/adsc.201000322
SN  - 1615-4150
ER  - 
TY  - JOUR
A1  - Bramborg, Andrea
A1  - Linker, Torsten
T1  - Regioselective synthesis of alkylarenes by two-step ipso-substitution of aromatic dicarboxylic acids
JF  - European journal of organic chemistry
N2  - A strategy for the regioselective alkylation of arenes was developed, starting from commercially available and inexpensive terephthalic acid or naphthalene-1,4-dicarboxylic acid. The method entails a formal ipso-substitution of the carboxylate groups by a sequence of reductive alkylation under Birch conditions and subsequent acid-mediated rearomatization with loss of carbon monoxide and carbon dioxide. More than 20 different arenes with various side-chains were synthesized. With naphthalene-1,4-dicarboxylic acid as starting material, we were able to control the degree of alkylation by choosing the appropriate electrophile in the Birch reduction. Thus, bisalkylated naphthalenes and naphthoic acids became available chemoselectively. All reactions afforded a single regioisomer exclusively in high yields. Overall, aromatic dicarboxylic acids are suitable substrates for a two-step ipso-substitution that allows the selective synthesis of alkylated benzenes and naphthalenes.
KW  - Synthetic methods
KW  - Alkylation
KW  - Birch reduction
KW  - Arenes
KW  - Regioselectivity
Y1  - 2012
U6  - https://doi.org/10.1002/ejoc.201200823
SN  - 1434-193X
IS  - 28
SP  - 5552
EP  - 5563
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Linker, Torsten
A1  - Bramborg, Andrea
A1  - Kelling, Alexandra
A1  - Schilde, Uwe
T1  - Crystal structure of trans-1,4-di-(2-(allyloxyethyl)-cyclohexa-2,5-diene-1,4-dicarboxylic acid, C18H24O6
JF  - Zeitschrift für Kristallographie : international journal for structural, physical and chemical aspects of crystalline materials ; New crystal structures
N2  - C18H24O6, triclinic, P (1) over bar (no. 2), a = 5.726(1) angstrom, b = 8.845(2) angstrom, c = 9.557(2) angstrom, alpha = 105.27(1)degrees, beta = 102.76(1)degrees, gamma = 103.49(1)degrees, V = 433.0 angstrom(3), Z = 1, R-gt(F) = 0.0412, wR(ref)(F-2) = 0.1075, T = 210 K.
Y1  - 2013
U6  - https://doi.org/10.1524/ncrs.2013.0124
SN  - 1433-7266
VL  - 228
IS  - 2
SP  - 243
EP  - 244
PB  - De Gruyter Oldenbourg
CY  - München
ER  - 
TY  - JOUR
A1  - Krüger, Tobias
A1  - Bramborg, Andrea
A1  - Kelling, Alexandra
A1  - Sperlich, Eric
A1  - Linker, Torsten
T1  - Birch Reduction of Arenes as an Easy Entry to γ-Spirolactones
JF  - European journal of organic chemistry
N2  - A convenient method for the synthesis of γ-spirolactones in only 2–3 steps is described. Birch reduction of inexpensive and commercially available aromatic carboxylic acids in the presence of ethylene oxide affords hydroxy acids, which undergo direct lactonization during work-up. Suitable precursors are methyl-substituted benzoic acids, naphthoic, and dicarboxylic acids. Subsequent hydrogenation proceeds smoothly with Pd/C as catalyst and saturated γ-spirolactones are isolated in excellent yields and stereoselectivities. Thus, up to 3 new stereogenic centers can be constructed as sole diastereomers from achiral benzoic acids. Furthermore, it is possible to control the degree of saturation with Raney nickel or Wilkinson's catalyst to obtain products with 1 double bond. Overall, more than 30 new γ-spirolactones have been synthesized in analytically pure form.
KW  - Arenes
KW  - Birch reduction
KW  - Hydrogenation
KW  - Lactones
KW  - Synthetic methods
Y1  - 2021
U6  - https://doi.org/10.1002/ejoc.202101018
SN  - 1434-193X
SN  - 1099-0690
VL  - 2021
IS  - 46
SP  - 6383
EP  - 6391
PB  - Wiley-VCH
CY  - Weinheim
ER  -