The preferred conformation of N-ethyl-2,2,2′-trichlorobenzoylacetanilide (1f) was deduced from 1H NMR data and served to account for the failure of 1f to cyclize in H2SO4 in terms of a steric hindrance to attainment of the requisite conformation for ring closure. Consistent with this view was the observation that pentachlorodihydroquinolinone 7a with H2SO4 underwent ring opening to give as chief product alkene 8, and only a minor amount of indenoquinolinone 2. Substrate 7a was formed, in preference to amide 11, from difluorooxyborane 6a and SO2Cl2, on allowing HCl to escape from the reaction mixture.
|Number of pages||4|
|Journal||Journal of Organic Chemistry|
|Publication status||Published - 1980|