TY  - JOUR
A1  - Wessig, Pablo
A1  - Krebs, Saskia
T1  - N-aroylsulfonamide-photofragmentation (ASAP)
BT  - a versatile route to biaryls
JF  - European journal of organic chemistry
N2  - The photochemical fragmentation of N-aroylsulfonamides 9 (ASAP) is a powerful method for the preparation of various biaryls. Compounds 9 are easily accessible in two steps from amines by treatment with arenesulfonyl chlorides and aroyl chlorides. Many of these compounds were prepared for the first time. The irradiation takes place in a previously developed continuous-flow reactor using inexpensive UVB or UVC fluorescent lamps. Isocyanates and sulphur dioxide are formed as the only by-products. The ASAP tolerates a variety of functional groups and is even suited for the preparation of phenylnaphthalenes and terphenyls. The ASAP mechanism was elucidated by interaction of photophysical and quantum chemical (DFT) methods and revealed a spirocyclic biradical as key intermediate.
KW  - Biaryls
KW  - Fragmentation
KW  - Isocyanates
KW  - Photochemistry
KW  - Sulfonamides
Y1  - 2021
U6  - https://doi.org/10.1002/ejoc.202100955
SN  - 1434-193X
SN  - 1099-0690
VL  - 2021
IS  - 46
SP  - 6367
EP  - 6374
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wolf, Thomas J. A.
A1  - Sanchez, David M.
A1  - Yang, J.
A1  - Parrish, R. M.
A1  - Nunes, J. P. F.
A1  - Centurion, M.
A1  - Coffee, R.
A1  - Cryan, J. P.
A1  - Gühr, Markus
A1  - Hegazy, Kareem
A1  - Kirrander, Adam
A1  - Li, R. K.
A1  - Ruddock, J.
A1  - Shen, Xiaozhe
A1  - Vecchione, T.
A1  - Weathersby, S. P.
A1  - Weber, Peter M.
A1  - Wilkin, K.
A1  - Yong, Haiwang
A1  - Zheng, Q.
A1  - Wang, X. J.
A1  - Minitti, Michael P.
A1  - Martinez, Todd J.
T1  - The photochemical ring-opening of 1,3-cyclohexadiene imaged by ultrafast electron diffraction
JF  - Nature chemistry
N2  - The ultrafast photoinduced ring-opening of 1,3-cyclohexadiene constitutes a textbook example of electrocyclic reactions in organic chemistry and a model for photobiological reactions in vitamin D synthesis. Although the relaxation from the photoexcited electronic state during the ring-opening has been investigated in numerous studies, the accompanying changes in atomic distance have not been resolved. Here we present a direct and unambiguous observation of the ring-opening reaction path on the femtosecond timescale and subangstrom length scale using megaelectronvolt ultrafast electron diffraction. We followed the carbon-carbon bond dissociation and the structural opening of the 1,3-cyclohexadiene ring by the direct measurement of time-dependent changes in the distribution of interatomic distances. We observed a substantial acceleration of the ring-opening motion after internal conversion to the ground state due to a steepening of the electronic potential gradient towards the product minima. The ring-opening motion transforms into rotation of the terminal ethylene groups in the photoproduct 1,3,5-hexatriene on the subpicosecond timescale.
KW  - Organic chemistry
KW  - Photochemistry
KW  - Physical chemistry
KW  - Theoretical chemistry
Y1  - 2019
U6  - https://doi.org/10.1038/s41557-019-0252-7
SN  - 1755-4330
SN  - 1755-4349
VL  - 11
IS  - 6
SP  - 504
EP  - 509
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Wessig, Pablo
A1  - Pick, Charlotte
T1  - Photochemical synthesis and properties of axially chiral naphthylpyridines
JF  - Journal of photochemistry and photobiology : A, Chemistry
N2  - Five alkynyl pyridines were prepared and cyclized to naphthylpyridines as the main products in the course of a Photo-Dehydro-Diels-Alder reaction. Four of the final products are axially chiral and the determination of the rotational barrier by DFT calculations, dynamic NMR and H PLC experiments is demonstrated. (C) 2011 Elsevier B.V. All rights reserved.
KW  - Photochemistry
KW  - Axial chirality
KW  - Photo-Dehydro-Diels-Alder reaction
KW  - Dynamic NMR
KW  - Dynamic HPLC
KW  - Molecular modeling
Y1  - 2011
U6  - https://doi.org/10.1016/j.jphotochem.2011.06.006
SN  - 1010-6030
VL  - 222
IS  - 1
SP  - 263
EP  - 265
PB  - Elsevier
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Wessig, Pablo
A1  - Pick, Charlotte
A1  - Schilde, Uwe
T1  - First example of an atropselective dehydro-Diels-Alder (ADDA) reaction
JF  - Tetrahedron letters
N2  - A new concept of a stereoselective synthesis of axially chiral biaryls, formed in the course of the dehydro-Diels-Alder (DDA) reaction, has been disclosed. It is based on asymmetric induction of the newly formed chirality axis by a chirality center, which is present in the two synthesized DDA reactants. Depending on the different length of the linkers joining the alkyne moieties the DDA reaction may be triggered photochemically or thermally, where only the thermal variant was stereoselective.
KW  - Cycloaddition
KW  - Atropselecrivity
KW  - Biaryls
KW  - Alkynes
KW  - Photochemistry
Y1  - 2011
U6  - https://doi.org/10.1016/j.tetlet.2011.06.024
SN  - 0040-4039
VL  - 52
IS  - 32
SP  - 4221
EP  - 4223
PB  - Elsevier
CY  - Oxford
ER  -