TY  - JOUR
A1  - Wessig, Pablo
A1  - Matthes, Annika
A1  - Schilde, Uwe
A1  - Kelling, Alexandra
T1  - Asymmetric synthesis of (1,5)Naphthalenophanes by Dehydro-Diels-Alder reaction
JF  - European journal of organic chemistry
N2  - An asymmetric variant of the dehydro-Diels-Alder (DDA) reaction has been developed and applied in the atropselective synthesis of various (1,5)naphthalenophanes. Whereas the suitability of the photochemically induced DDA (PDDA) was limited, the thermally induced DDA provided the desired product, depending on the chiral auxiliary used and the length of the linker, with nearly perfect stereoselectivity. Furthermore, the mechanism of the DDA was investigated by means of DFT calculations, and a stepwise mechanism involving 1,4-biradicals was suggested.
KW  - Synthetic methods
KW  - Macrocycles
KW  - Cyclophanes
KW  - Atropisomerism
KW  - Chiral auxiliaries
KW  - Density functional calculations
Y1  - 2013
U6  - https://doi.org/10.1002/ejoc.201201594
SN  - 1434-193X
IS  - 11
SP  - 2123
EP  - 2129
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Dzambaski, Zdravko
A1  - Markovic, Rade
A1  - Kleinpeter, Erich
A1  - Baranac-Stojanovic, Marija
T1  - 2-Alkylidene-4-oxothiazolidine S-oxides - synthesis and stereochemistry
JF  - Tetrahedron
N2  - A series of 5-unsubstituted and 5-substituted 2-alkylidene-4-oxothiazolidine-S-oxides were synthesized by the sulfur-oxidation with m-CPBA. The stereochemistry of 5-substituted sulfoxides was determined by means of NMR spectroscopy and DFT theoretical calculations. It was found that the thermodynamically less stable anti-isomer was initially formed in the course of the oxidation, but it underwent epimerization to the mixture enriched in the more stable syn-isomer, during the work-up process. The higher stability of syn-isomers is ascribed to the stronger hyperconjugative sigma(C-H)->sigma*(S-O) interaction versus the weaker sigma(C-C)->sigma*(S-O) delocalization in their anti-counterparts and to the existence of intramolecular 1,5-CH center dot center dot center dot C hydrogen bonds.
KW  - 2-Alkylidene-4-oxothiazolidine
KW  - Sulfoxide
KW  - Diastereoselectivity
KW  - Density functional calculations
KW  - CH center dot center dot center dot O hydrogen bonds
Y1  - 2013
U6  - https://doi.org/10.1016/j.tet.2013.05.087
SN  - 0040-4020
VL  - 69
IS  - 31
SP  - 6436
EP  - 6447
PB  - Elsevier
CY  - Oxford
ER  -