1,5-Sigmatropic formyl migration in 1,3-dimethylbenz[f]indene-1-carbaldehyde; evidence for product-like transition states
作者:David W. Jones、Robert J. Marmon
DOI:10.1039/p19900003271
日期:——
The title compound 1 has been prepared in an optically active form via a convenient seven-step sequence. The migratory ability of the formyl group allows the 1,5-shift 1 (arrows) involving disruption of naphthalene aromaticity to proceed with modest activation [DELTA-G double-ended dagger = 31.84 +/- 0.6 kcal mol-1 (145-degrees-C)]. Activation enthalpies for 1,5-formyl migration in 1, 3, 4 and 5 correlate well with changes in pi-electron energy in going from these compounds to their respective rearrangement products. Product-like transition states involving important cleavage of the bond between the migration origin and the formyl group are suggested for these rearrangements.