TY  - JOUR
A1  - Goldberg, Mariano
A1  - Sartakov, Denis
A1  - Bats, Jan W.
A1  - Bolte, Michael
A1  - Göbel, Michael
T1  - A chiral analog of the bicyclic guanidine TBD : synthesis, structure and Brønsted base catalysis
T2  - Beilstein journal of organic chemistry
N2  - Starting from (S)-β-phenylalanine, easily accessible by lipase-catalyzed kinetic resolution, a chiral triamine was assembled by a reductive amination and finally cyclized to form the title compound 10. In the crystals of the guanidinium benzoate salt the six membered rings of 10 adopt conformations close to an envelope with the phenyl substituents in pseudo-axial positions. The unprotonated guanidine 10 catalyzes Diels–Alder reactions of anthrones and maleimides (25–30% ee). It also promotes as a strong Brønsted base the retro-aldol reaction of some cycloadducts with kinetic resolution of the enantiomers. In three cases, the retro-aldol products (48–83% ee) could be recrystallized to high enantiopurity (≥95% ee). The absolute configuration of several compounds is supported by anomalous X-ray diffraction and by chemical correlation.
KW  - absolute configuration
KW  - anthrone
KW  - cycloaddition
KW  - kinetic resolution
KW  - lipase
Y1  - 2016
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/44541
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-445417
SN  - 1860-5397
N1  - License and Terms: This is an Open Access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
VL  - 12
SP  - 1870
EP  - 1876
PB  - Beilstein-Institut zur Förderung der Chemischen Wissenschaften
CY  - Frankfurt, Main
ER  -