COMPETITION BETWEEN ADDITION AND REDOX PROCESSES IN REACTIONS OF NITROARENES WITH LITHIUM-DITHIANES

Article abstract of DOI:10.1016/0040-4020(86)80023-0

The reaction of 2-lithio-1,3-dithianes with nitroarenes gives 2-(or 4-)<(1,3-dithian)-2'-yl>cyclohexa-3,5(or 2,5-)-diene-1-nitronate compounds (conjugate-addition products), free nitroarene radical anions (redox products), 1,3-dithianes and 2,2'-bis-(1,3-dithianes).The conjugate-addition and redox products were converted in the respective nitroaromatic compounds by oxidation in situ with O2 or DDQ.The ratio between addition and redox products increases with decrease of temperature. 2-H-2-Lithio-1,3-dithiane can give both 1,4- and 1,6-addition products, while 2-methyl- and 2-phenyl derivatives give only 1,6-addition products.A mechanism involving an s.e.t. from lithium dithianes to nitroarenes followed by various decay routes is suggested for the two radical species.