Photochemical transformation of S-aryl 2-benzoylbenzothioates to 3-phenyl-3-arylthiobenzofuranones involving aryl migration

S-Phenyl 4-cyanothiobenzoate

“…(I) crystallizes in the non-centrosymmetric monoclinic space group P2 1 and participates in very weak intermolecular hydrogen bonds (Table 1). The observed structure of (I) is in good agreement with those determined for other S-phenyl thiobenzoates (Allouchi et al, 1995;Chrusciel et al, 1995;Ganesh et al, 2005;Jovanovski et al, 1993;Karczmarzyk et al, 2001;Low et al, 2000;Sakamoto et al, 1996;Takahashi, Sekine et al, 1998;Takahashi, Fujita et al, 1998).…”

Solid-State Photochemistry of o-Aroylbenzothioates: Absolute Asymmetric Phthalide Formation Involving 1,4-Aryl Migration

“…While the chemoselectivity decreased proportionately with the extent of irradiation, the enantioselectivity fell off seriously at earlier stages. These results indicate that nontopochemically controlled processes occurred in the crystal lattices at later reaction stages, which promoted nonselective reactions leading to complicated products including phthalide dimer as well as reaction in the solution phase . Indeed, the change in enantioselectivity was more sensitive than that in chemoselectivity.…”

“…Figure includes UV spectra of the crystals of thioesters 1a − c , indicating the molecules absorbed photons sufficiently in the solid state beyond 290 nm (Pyrex filtered light) . Accordingly, crystals of 1d − g bearing almost the same structures were expected to behave similarly on irradiation.…”

“…Remarkably, only one strong methyl signal, except for that of 1e , evolved around the region of 2.0−2.5 ppm, with weak signals due to phthalide dimer. The demonstration is incompatible with reaction in the solution phase . The characterization of the photoproduct was unequivocally established by the X-ray crystallographic analysis, which demonstrated the methyl probe was located at the 6-position of the phthalide system .…”

“…The X-ray crystallographic structures of both 1e and 2e have been reported in ref , and their crystal data were cited therein.…”