[reaction: see text] Palladium[0]-mediated Ullmann cross-coupling of o-halonitrobenzene (1) and various related nitroarenes with a range of alpha-halo-enones (e.g., 2) or -enals readily affords the expected alpha-arylenones, e.g., 3, or -enals, which are converted into the corresponding indoles, e.g., 4, on reaction with dihydrogen in the presence of Pd on C.
The readily available and enzymatically derived cis-1,2-dihydrocatechol 4 has been elaborated, over 11 steps including an Overman rearrangement, into the non-natural enantiomer, (-)-1, of the alkaloid lycoricidine [(+)-1]. Related chemistries have provided analogues 18, 19, and 26.
The readily available and enzymatically derived cis-1,2-dihydrocatechols 3a and 3b have been elaborated over 17 steps, including a novel radical addition/elimination sequence, into the enantiomer, (+)-1, of the montanine alkaloid brunsvigine [(-)-1].
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