A Study of the Photochemistry of Benzobicyclo[2.2.2]octan-2-ones

1988 ◽  
Vol 41 (3) ◽  
pp. 351 ◽  
Author(s):  
PLM Beckwith ◽  
EL Ghisalberti ◽  
PR Jefferies ◽  
CL Raston ◽  
AH White
Keyword(s):  
Diels Alder ◽  
X Ray ◽  
Alder Adduct

The anti- and syn-3-methyl isomers of 5,8-dimethoxy-1,3-dimethyl-3,4-dihydro-1,4-ethanonaphthalen-2(1H)-one (2) and (3) and the 1,3,3- trimethyl analogue (4) were prepared from the Diels -Alder adduct of benzoquinone and 1,3-dimethylcyclohexadiene. The photochemistry of each has been studied and the structures of several photoproducts have been assigned. One of the products from irradiation of (3) was found by X-ray analysis to be a 1,4-disubstituted 1,2,3,4- tetrahydronaphthalene [methyl 2-(5′,8′-dimethoxy-4z′-methyl-1′,2′,3′,4′-tetrahydronaphthalen-1′-yl) propanoate ] with the unexpected cis-stereochemistry (11). Irradiation of (4) produces, inter alia, a compound containing the unusual tetracyclo [7.4.0.02,7.04,8] trideca -1(9),10,12-triene skeleton whose structure was determined by n.m.r. spectroscopy.

Structural Study of an Unusual Diels-Alder Adduct

1992 ◽  
Vol 45 (12) ◽  
pp. 2089 ◽  
Author(s):  
EL Ghisalberti ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Structural Study ◽  
Spectroscopic Studies ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Chemical Evidence ◽  
Alder Adduct

The structure of the compound obtained on heating the naturally occurring clerodane furanoditerpene (1) had been formulated as (2) on the basis of spectroscopic studies. A single-crystal X-ray diffraction study on the dihydro derivative of (2) has confirmed this and provides support for the stereochemistry previously assigned to (1) on the basis of chemical evidence.

Synthesis and x-ray structure of a Diels-Alder adduct of fullerene C60

1993 ◽  
Vol 115 (1) ◽  
pp. 344-345 ◽  
Author(s):  
Yves Rubin ◽  
Saeed Khan ◽  
Daron I. Freedberg ◽  
Chahan Yeretzian
Keyword(s):  
Diels Alder ◽  
Fullerene C60 ◽  
X Ray ◽  
Alder Adduct

The Two-step Synthesis and Crystal and Molecular Structure of Tetracyclo[6.4.0.02,11.04,9]dodec-6-ene-3,10-dione

1975 ◽  
Vol 53 (14) ◽  
pp. 2068-2075 ◽  
Author(s):  
Yuen-Mui Ngan ◽  
Steven J. Rettig ◽  
John R. Scheffer ◽  
James Trotter
Keyword(s):  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Membered Ring ◽  
Diels Alder ◽  
High Yield ◽  
Side Chain ◽  
X Ray ◽  
Long Wavelength ◽  
Vinyl Group ◽  
Alder Adduct

The photochemistry of the trans-1,3,5-hexatriene-p-benzoquinone Diels–Alder adduct has been investigated. Irradiation of this material in its long wavelength n → π* absorption band leads to a single photoproduct in high yield. A single crystal X-ray structure determination shows this product to be tetracyclo[6.4.0.02,11.04,9]dodec-6-ene-3,10-dione, the result of a novel regiospecific intramolecular 2 + 2 photoaddition between the side chain vinyl group and the enedione double bond. Crystals of tetracyclo[6.4.0.02,11.04,9]dodec-6-ene-3,10-dione are monoclinic, a = 7.5290(7), b = 19.072(1), c = 6.7237(4) Å, β = 107.918(6) °, Z = 4, space group P21/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.041 for 1603 reflections with I ≥ 3σ(I). The structure consists of well-separated molecular units. Bond distances are: C=O, 1.216 and 1.219(2), C=C, 1.318(2), mean C(sp3)—C(sp2), 1.508, mean C(sp3)—C(sp3), 1.560 in the four-membered ring and 1.544 elsewhere, mean C(sp3)—H, 0.99, and mean C(sp2)—H, 0.95 Å. Bond distances between nonhy drogen atoms have been corrected for thermal motion. A possible rationalization for the observed photoprocess is discussed in terms of conformational and radical stability effects.

Chromium and Molybdenum Carbonyl Complexes of C7Ph7H and C7Ph5Me2H and of C7Ph7H(CO), the Diels-Alder Adduct of Tetracyclone and Triphenylcyclopropene: Variable-Temperature NMR and X-ray Crystallographic Study

1995 ◽  
Vol 14 (3) ◽  
pp. 1139-1151 ◽  
Author(s):  
Lisa C. F. Chao ◽  
Hari K. Gupta ◽  
Donald W. Hughes ◽  
James F. Britten ◽  
Suzie Rigby ◽  
...  
Keyword(s):  
Variable Temperature ◽  
Diels Alder ◽  
Carbonyl Complexes ◽  
X Ray ◽  
Crystallographic Study ◽  
Molybdenum Carbonyl ◽  
Alder Adduct

ChemInform Abstract: Synthesis and X-Ray Structure of a Diels-Alder Adduct of C60.

ChemInform ◽  
2010 ◽  
Vol 24 (19) ◽  
pp. no-no
Author(s):  
Y. RUBIN ◽  
S. KHAN ◽  
D. I. FREEDBERG ◽  
C. YERETZIAN
Keyword(s):  
Diels Alder ◽  
X Ray ◽  
Alder Adduct

Photochemical Isomerization of (E,Z)-1,5-Bis(9-anthryl)penta-1,4-dien-3-one and its Intramolecular Diels-Alder Adduct

1985 ◽  
Vol 38 (10) ◽  
pp. 1471 ◽  
Author(s):  
H Becker ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Molecular Structure ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
Skeletal Rearrangement ◽  
X Ray ◽  
Photochemical Isomerization ◽  
Alder Adduct

Photoexcitation of (E,Z)-1,5-bis(9-anthryl)penta-1,4-dien-3-one (2) leads to 4-(9-anthryl)-4,5-dihydro-5,9b[1′,2′]-benzeno-9bH- benz [e]indene-3(3aH)-one (3) which is formed by an intramolecular Diels -Alder addition. Upon irradiation, (3) undergoes a skeletal rearrangement to give a product (4), rationalized in terms of a stepwise reaction involving diradical intermediates. The molecular structure of (4) has been established by X-ray diffraction, and the stereochemistry of (3) deduced from the results of X-ray diffraction studies of its reduction products (5) and (6).

ChemInform Abstract: PREPARATION AND X-RAY STRUCTURE ANALYSIS OF THE DIELS-ALDER ADDUCT OF 4-PHENYL-4H-1,2,4-TRIAZOLE-3,5-DIONE WITH OCTAVALENE

1984 ◽  
Vol 15 (23) ◽  
Author(s):  
M. CHRISTL ◽  
R. LANG ◽  
W. REIMANN ◽  
H. IRNGARTINGER
Keyword(s):  
Structure Analysis ◽  
Diels Alder ◽  
X Ray ◽  
Alder Adduct

ChemInform Abstract: X-RAY DIFFRACTION STUDY OF THE DIELS-ALDER ADDUCT OF 4-PHENYL-1,2,4-TRIAZOLINE-3,5-DIONE WITH PREVITAMIN D3

1982 ◽  
Vol 13 (35) ◽  
Author(s):  
M. VAN MEERSSCHE ◽  
B. TINANT ◽  
G. GERMAIN ◽  
J.-P. DECLERCQ ◽  
L. J. VANMAELE ◽  
...  
Keyword(s):  
Diffraction Study ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alder Adduct

Syntheses of Angucyclinones Related to Ochromycinone

1998 ◽  
Vol 51 (6) ◽  
pp. 515 ◽  
Author(s):  
Tomas Rozek ◽  
Wit Janowski ◽  
John M. Hevko ◽  
Edward R. T. Tiekink ◽  
Suresh Dua ◽  
...  
Keyword(s):  
Structural Study ◽  
Alder Reaction ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
X Ray ◽  
Diels Alder Reaction ◽  
Synthetic Approaches ◽  
Alder Adduct

Two synthetic approaches have been investigated for the syntheses of model angucyclinones related to ochromycinone. The first involves a Diels–Alder/Friedel–Crafts strategy in which the Diels–Alder adduct formed between dimethyl acetylenedicarboxylate and 3-ethenyl-5,5-dimethylcyclohex-2-en-1- one was converted into 6,6-dimethyl-8-oxo-5,6,7,8-tetrahydronaphthalene-1,2-dicarboxylic anhydride, which was then reacted with benzene in a Friedel–Crafts reaction. Acid-catalysed cyclization of the Friedel–Crafts products gave 3,3-dimethyl-3,4-dihydrobenz[a]anthracene-1,7,12(2H)-trione (3) in poor yield. Angucyclinones related to (3) are formed (in 40–50% overall yield) by aromatization of the adduct formed between the appropriate 1,4-naphthoquinone and 3-[(E)-2-methoxyethenyl]- 5,5-dimethylcyclohex-2-en-1-one (this dienone reacts with itself by a Diels–Alder process to yield an adduct which decomposes to 3,3,8,8-tetramethyl-3,4,7,8-tetrahydroanthracene-1,6(2H,5H)-dione). When the substituted 1,4-naphthoquinone is unsymmetrical, a boron triacetate assisted Diels–Alder reaction gives a single regioisomer (e.g. X-ray investigations indicate that 8-hydroxy-3,3-dimethyl-3,4-dihydrobenz[a]anthracene-1,7,12(2H)-trione is the product from 5-hydroxy-1,4-naphthoquinone). An X-ray structural study of the Diels–Alder adduct in the above reaction confirms the operation of an endo cyclization.

Syntheses of Angucyclinones Related to Ochromycinone. III. An 11-Hydroxy Isomer and Some Reduced Analogues

1999 ◽  
Vol 52 (2) ◽  
pp. 129 ◽  
Author(s):  
Tomas Rozek ◽  
Tomas Rozek ◽  
Dennis K. Taylor ◽  
Dennis K. Taylor ◽  
Edward R. T. Tiekink ◽  
...  
Keyword(s):  
Hydroxy Group ◽  
Alder Reaction ◽  
Diels Alder ◽  
X Ray ◽  
X Ray Crystallography ◽  
Diels Alder Reaction ◽  
Stereo Selectivity ◽  
Hydrolysis Of ◽  
Alder Adduct

The boron triacetate assisted Diels Alder reaction between racemic 5,5-dimethyl-3-vinylcyclohex- 2-enyl acetate and 5-hydroxynaphthoquinone yields the racemic 11-hydroxy-3,3-dimethyl-7,12-dioxo- 1,2,3,4,6,6a,7,12,12a,12b-decahydrobenzo[a]anthracen-1-yl acetate as the sole stereoisomer by regio- and stereo-selective cis endo addition. Aromatization of the Diels Alder adduct followed by hydrolysis of the acetate and oxidation of the resultant 1-hydroxy group gives the target angucyclinone, 11-hydroxy-3,3-dimethyl-1,2,3,4,7,12-hexahydrobenzo[a]anthracene-1,7,12-trione, in an overall yield of 37% from 5-hydroxynaphthoquinone. The regio- and stereo-selectivity of the Diels Alder addition is confirmed by a combination of 13C n.m.r. spectroscopy and X-ray crystallography.

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