Reactions of lithium phenylacetylenide and lithium 3,3-dimethylbut-1-ynidewith 3,6-di-tert-butyl-1,2-benzoquinone. Molecular structure of 2,5-di-tert- butyl-8-(3,6-di-tert-butyl-1,2-binzoquinon-4-yl)-8-phenylocta-2,4,6,7-tetraen-1,6-olide
Ga. Abakumov et al., Reactions of lithium phenylacetylenide and lithium 3,3-dimethylbut-1-ynidewith 3,6-di-tert-butyl-1,2-benzoquinone. Molecular structure of 2,5-di-tert- butyl-8-(3,6-di-tert-butyl-1,2-binzoquinon-4-yl)-8-phenylocta-2,4,6,7-tetraen-1,6-olide, RUSS CHEM B, 48(2), 1999, pp. 350-355
Reactions of 3,6-di-tert-butyl-1,2-benzoquinone with PhC=CLi and (BuC)-C-t=
CLi are multistage processes. In;the first stage, nucleophilic 1,2-addition
of the organometallic compound to o-benzoquinone occurs to form the corres
ponding hydroxycyclohexadienone derivative. In polar solvents, the latter u
ndergoes rearrangement through insertion of the oxygen atom into the ring t
o form a new allenic organolithium compound. The reaction of the newly form
ed organometallic compound with the initial o-quinone occurs either as a on
e-electron transfer to yield lithium semiquinolate and a dimerization produ
ct; viz., 4,4'-bi(2,5-di-tert-butyl-9,9-dimethyldeca-2,5-dien-7-yn-1,6-olid
e), or as the 1,4-addition to yield 2,5-di-tert-butyl-8-(3,6-di-tert-butyl-
1,2-benzoquinon-4-yl)-8-phenylocta-2,4,6,7- tetraen-1,6-olide. The structur
e of the latter compound was established by X-ray diffraction analysis and
by NMR and IR spectroscopy.