Three tetramethylketals of 2,5-distyryl-[1,4]benzoquinones

Irngartinger, Hermann; Lichtenthäler, Jochen

doi:10.1107/s0108270193011503

Cited by 1 publication

(3 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More details on the structure determination are given in Table 10 [13] . For (E,E)-2,5-bis(2-ethoxycarbonylethenyl)-1,4-dimethoxybenzene (6), (E,E)-1,4-bis(2-ethoxycarbonylethenyl)-3,3-dimethoxy-6-oxocyclohexa-1,4-diene (8) and (E,E)-2,5-bis(2-ethoxycarbonylethenyl)-1,4-benzoquinone (1b) the coordinates of the hydrogen atoms and their thermal parameters were fixed during refinement. One of the ethyl groups from compound (8) was disordered (50%).…”

Section: General Procedures For the Synthesis Of The Quinones 1aϫ1fmentioning

confidence: 99%

“…13 C-NMR data of 5, 6, 7aϪ7f; carbon atoms: (a) methoxy; (b) C(ϪO) (ring); (c) C(ϪC) (ring); (d) C(ϪH) (ring); (e) vinyl C (ring); (f) vinyl C (ester); (g) carbonyl C; (h)Ϫ(l) CH 2 and CH 3 groups of the ester; (m)Ϫ(p) phenyl C of benzyl groups of 7f 13 Table 5b. 13 C-NMR data of the quinones 1aϪ1f; assignment of the carbon atoms as in Table 5a 13 (8): To a solution of 0.5 g (1.4 mmol) of the quinone bisketal 7b in 10 ml of DMF (abs. ), 1 drop of sulfuric acid (2 ) was added.…”

Section: General Procedures For the Synthesis Of The Quinones 1aϫ1fmentioning

confidence: 99%

“…[13] The methoxy groups have a gauche/anti orientation. [8] The methoxy groups of the semiketal 8 have an anti/anti orientation in the crystal. [13] Crystal and Molecular Structure of the Quinone 1b…”

Section: Syntheses Of (Ee)-25-bis(2-alkoxycarbonylethenyl)-14-benzmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis and Topochemistry of 2,5-Bisacrylate-Substituted 1,4-Benzoquinones

Irngartinger¹,

Herpich

1998

Eur. J. Org. Chem.

View full text Add to dashboard Cite

The 2,5‐bisacrylate‐substituted 1,4‐benzoquinone bisketal 7a was synthesized by electrochemical oxidation of the corresponding dimethoxybenzene 6. The methyl ester 7a was transesterified to the corresponding ethyl, n‐propyl and isopropyl esters 7b−7d by Ti(OEt)4 catalysis and to the corresponding n‐butyl and benzyl esters 7e−7f by the Li alkoxides. The bisketals 7a−7f were hydrolyzed to the corresponding 2,5‐bisacrylate‐substituted 1,4‐benzoquinones 1a−1f. The crystal structure of the ethyl ester 1b was determined by X‐ray diffraction, which revealed short intermolecular contacts of 3.463 and 4.051 Å between vinyl groups and quinone double bonds, respectively, related by twofold symmetry. Because of the shorter distance and the smaller shift in projection (vinyl: 1.002; quinone: 2.107 Å), only the vinyl group is photoactive in the crystal. In the solid state, topochemically controlled [2+2] photocycloadditions take place at the vinylic groups of the bisvinyl quinones 1a−1f, to afford dimers and oligomers (nmax = 7), under topochemical control. The cyclobutane units generated from 1b and from 1c−1f have twofold and centric symmetry, respectively, as determined by 1H‐NMR spectroscopy and simulation thereof. The twofold symmetry in the cycloaddition products of 1b is in agreement with the crystal structure of the monomers.

show abstract

Section: General Procedures For the Synthesis Of The Quinones 1aϫ1fmentioning

confidence: 99%

Section: General Procedures For the Synthesis Of The Quinones 1aϫ1fmentioning

confidence: 99%