title: Overcoming Strain-Induced Rearrangement Reactions: A Mild Dehydrative Aromatization Protocol for Synthesis of Highly Distorted p-Phenylenes.
abstract: A series of p-terphenyl-based macrocycles, containing highly distorted p-phenylene units, have been synthesized. Biaryl bonds of the nonplanar p-terphenyl nuclei were constructed in the absence of Pd-catalyzed or Ni-mediated cross-coupling reactions, using 1,4-diketones as surrogates to strained arene units. A streamlined synthetic protocol for the synthesis of 1,4-diketo macrocycles has been developed, using only 2.5 mol % of the Hoveyda-Grubbs second-generation catalyst in both metathesis and transfer hydrogenation reactions. Under protic acid-mediated dehydrative aromatization conditions, the central and most strained benzene ring of the p-terphenyl systems was susceptible to rearrangement reactions. To overcome this, a dehydrative aromatization protocol using the Burgess reagent was developed. Under these conditions, no strain-induced rearrangement reactions occur, delivering p-phenylene units with up to 28.4 kcal/mol strain energy and deformation angles that sum up to 40°.
authors: Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States.
authors: Nirmal K
authors: NK
authors: Mitra
authors: Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States.
authors: Rolande
authors: R
authors: Meudom
authors: Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States.
authors: Hector H
authors: HH
authors: Corzo
authors: Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States.
authors: John D
authors: JD
authors: Gorden
authors: Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States.
authors: Bradley L
authors: BL
authors: Merner