New Methods of Formation of Meta-Substituted Aromatic Compounds

Article abstract of DOI:10.1021/jo00370a024

The addition of organolithium reagents to the oxa tricyclic ketone 1 occurs stereospecifically to produce the corresponding tertiary carbinols 2a-d.When the alcohols 2a-d are treated with TiCl4, ring fragmentation and dehydration occur to produce good yields of 5,6-dihydrobenzaldehydes 3a-d.Oxidation of aldehydes 3a-d then leads to the corresponding meta-substituted benzaldehydes 4a-d.Alternatively, use of the Lewis acid Me2BBr did not stop at the dihydrobenzaldehyde stage.Tautomerization of the diene aldehydes 3a-d produced meta-substituted benzyl alcohols 7a-d or benzyl bromides 8a-d under prolonged reaction times.The addition of silica gel to the reactions accelerated the formation of the benzyl bromides.