Reactions of quinones with ylides

Wittig reaction of 1‐dicyanomethyleneacenaphthen‐2‐one

“…It is reasonable to assume that the initial dipolar structure 6, formed from 1 and 2, partly, was converted by an internal Wittig reaction to 10 (Scheme 2). A similar result was observed during an intramolecular Wittig olefination reaction by Sorensen [ 101 and others [ 1 1, 121. characteristic of the C=P absorption group [13], as well as around 1420 cm-I for the P-C, phenyl. (3) The PMR spectrum of 1 1 in DMSO showed only a multiplet in the region 6, 6.76-8.68, due to the aromatic protons.…”

Synthesis of Some [1,3]Benzodioxoles via the Reaction of o-Quinones with Phosphorus Ylides

“…When quinone 1c was treated with tetrahydro-2-furanylmethyl-(triphenyl)phosphonium bromide, as described in Method B, for 45 h, it gave (E )-4-[4,6-di(tert-butyl)benzo[d] [1,3]dioxol-2-yl-3-buten-1-ol 10 in 27% yield along with 3,5-di(tert-butyl)-1,2-benzenediol (38%) and unreacted quinone 1c (25%). Obviously, tautomerization of the expected ylide 8 initially formed to the ylide 9 via the opening of the tetrahydrofuran ring; the reaction conditions 22 and further reaction of the latter with 1c can account for the formation of the product 10 obtained (Scheme 2).…”

“…The reaction of commercial 1,2-naphthoquinone 18 with the ylide 2j according to Method B resulted in a complicated mixture of products. Separation of the reaction mixture by column chromatography gave from the faster moving band 2-methyl-2-phenyl-5- [1,3]dioxole 20 in 20% yield (Scheme 4). The structure suggested for this product agrees well with the recorded analytical and spectral data, and especially with the MS, 1 H-NMR, and the 13 C-NMR data, which reveal the symmetry of the structure.…”

“…However, it must be noted that in contrast to above observations Wittig olefination also has been observed to proceed between the quinones 1a, 1c and the ylides Ph 3 P COOR, Ph 3 P CHCOR, Ph 3 P CBr 2 6,13,14 as well as between the ylide 2e and quinone 11. 1 Sidky and Boulos 18 and later Abdou 19 suggested the following mechanistic reaction sequence 1 + 2 → 24 → 25 → 26 → 3 (Scheme 5) in order to explain the formation of 1,3-dioxoles 3 from the reactions between 1a-c and 2d-f.…”

“…Bestmann and Lang 8 reported in 1969 that tetrachloro-o-benzoquinone 1a reacts with benzylidene(triphenyl)phosphorane 2a to give 2-phenylmethylene-4,5,6,7-tetrachloro-1,3-benzodioxole 3 (R 1 R 2 R 3 R 4 Cl, R 5 H, R 6 Ph) and triphenylphosphine. The corresponding [1,3]benzodioxoles 3 also were obtained from the reaction of the same o-quinone 1a with ylides 2b, 17 2c, 2 2d-f, 18 and 2g, 5 as well as from the reactions of 2d-f with quinone 1b. 18 The formation of the corresponding 1,3-dioxoles in high yields (82-90%), instead of Wittig products also was reported to proceed in the reactions of 3,5-di(tert-butyl)benzo-1,2-quinone 1c with ylides 2d-f (Scheme 1).…”