52866-48-5Relevant articles and documents
New Methods of Formation of Meta-Substituted Aromatic Compounds
Adams, Julian,Belley, Michel
, p. 3878 - 3881 (2007/10/02)
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.
Uncatalyzed Sigmatropic 1,5-Shift of Acyl Groups in the Thermolysis of 5-Acyl-5-methyl-1,3-cyclohexadienes
Schiess, Peter,Dinkel, Rolf,Fuenfschilling, Peter
, p. 787 - 800 (2007/10/02)
Four different 5-acyl-5-methyl-1,3-cyclohexadienes 1a-d (R=COOCH3, COCH3, COC6H5, CHO) have been shown to yield mixtures of 1,3-disubstituted cyclohexadienes 2-7 and 1,3-disubstituted aromatic product 8 upon thermolysis at 150-300 deg C in solution and at 350-500 deg C in the gas phase in a flow system.Two reaction pathways are considered for the rearrangement of the C-Skeleton.For the ester 1a 13C-isotopic substitution shows that products arise to 75-86percent through a 1,5-sigmatropic shift of the methoxycarbonyl group and to 14-25percent through a sequence of reaction steps involving a 1,7-H-shift reaction in an acyclic intermediate.For the more reactive compounds 1b-d isomerization is assumed to follow the 1,5-sigmatropic pathway exclusively.A kinetic study yields the following sequence for the migration tendency of acyl groups toward sigmatropic 1,5-shift: COOCH3 COCH3 COC6H5 CHO.
