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DOI:10.15227/orgsyn.068.0198

Organic Syntheses, Coll. Vol. 8, p.298 (1993); Vol. 68, p.198 (1990).

DOMINO DIELS–ALDER REACTION: 3,3a,3b,4,6a,7aHEXAHYDRO-3,4,7-METHENO-7H-CYCLOPENTA[a]PENTALENE-7,8-DICARBOXYLIC ACID
[3,4,7-Metheno-7H-cyclopenta[a]pentalene-7,8-dicarboxylic acid, 3,3a,3b,4,6a,7ahexahydro]

Submitted by Richard T. Taylor1, Michael W. Pelter1, and Leo A. Paquette2.
Checked by Katsunori Nagai and Ryoji Noyori.

1. Procedure
All apparatuses for Steps A and B should be dried overnight in an oven.
A. 9,10-Dihydrofulvalene. A 5-L, three-necked, round-bottomed flask is fitted, while hot, with a
Hirschberg stirrer, gas inlet, and stopper (Note 1). The assembled apparatus is flame-dried and allowed
to cool to room temperature under a stream of dry, oxygen-free argon (Note 2). The stopper is replacedwith a powder funnel and, under a sweep of positive argon, 100 g (4.17 mol) of dry sodium hydride(Note 3) is added followed by 2.0 L of dry tetrahydrofuran (Note 4). The powder funnel is replaced by a
500-mL, pressure-equalizing, jacketed addition funnel that is flushed with argon, then stoppered.
The stirred sodium hydride suspension is cooled by an external ice–water bath and the jacket of theaddition funnel is cooled in a dry ice–isopropyl alcohol bath. Into the addition funnel is introduced 275
g (4.16 mol) of neat, freshly distilled cyclopentadiene (Note 5). The cyclopentadiene is added rapidly,
dropwise over 30–40 min to the stirred slurry (Caution: Avoid excess foaming.) (Note 6). After theaddition is complete, the cooling bath is removed and the solution is stirred for 1 hr at room
temperature.
The jacketed addition funnel is removed and 1.5 g of cuprous bromide–dimethyl sulfide complex(Note 7) is added through a powder funnel. A 500-mL, pressure-equalizing addition funnel (longtipped) is attached to the flask and flushed with argon. As the anion solution is cooled in a dry ice–
isopropyl alcohol bath, a solution of 530 g (2.08 mol) of sublimed iodine in 500 mL of anhydrous
tetrahydrofuran is placed in the addition funnel. This solution is added dropwise to the cooled slurryover approximately 90 min (Note 8). The solution is stirred for about 15 min at low temperature.
B. Diels–Alder reaction. A 500-mL, pressure-equalizing addition funnel containing 330 g (2.32mol) of dimethyl acetylenedicarboxylate (Note 9) is placed in the flask and the ester is added rapidly
dropwise over 10 min. The solution is stirred for 30 min, the cooling bath is removed, and stirring ismaintained for 4 hr (Note 10).
The reaction solution is filtered through a Celite pad (ca. 5 cm thick on a 32-cm Büchner funnel),and the solid is washed repeatedly with tetrahydrofuran (1.5 L). The combined filtrates are concentrated
under reduced pressure at a temperature not above 30°C. To the concentrate is added 1.5 L of ether. The
solution is stirred for 15 min, again filtered through Celite, and concentrated at 30°C (Note 11).
C. Hydrolysis. Into a three-necked, 5-L, round-bottomed flask equipped with mechanical stirrer,thermometer, and 500-mL addition funnel with gas inlet is placed the above concentrate and 2 L ofmethanol. The solution is cooled to −5 to 0°C by means of an ice–salt bath. A precooled (0°C) solution
containing 220 g of 87.5% potassium hydroxide in 400 mL of water is added dropwise at such a rate as
to keep the reaction temperature below 10°C. The reaction mixture is stirred for an additional 2 hr at 0°
C and for 1 hr at room temperature prior to the addition of 100 mL of glacial acetic acid. Solid sodium
carbonate is added to bring the pH to 8 and the solution is filtered through Celite. Concentration off thefiltrate at 35°C and reduced pressure affords about 1 L of a dark liquid. The liquid is diluted with 2 L ofwater and extracted with petroleum ether (6 × 600 mL). The combined extracts are washed withaqueous sodium thiosulfate solution (800 mL) and dried (magnesium sulfate). Concentration at 30°C
affords a clear red liquid (occasionally a yellow solid) which is almost pure internal diester (Note 12).
The diester is dissolved in 130 mL of methanol, placed in a 1-L, one-necked flask equipped with amagnetic stirring bar and reflux condenser, and treated with a solution containing 35 g of potassiumhydroxide in 130 mL of water. The mixture is stirred at reflux temperature for 1 hr. Methanol isremoved under reduced pressure and 250 mL of water is added. Heating is continued for another 5 hr.
After the solution is cooled, 5 g of activated charcoal is added and the mixture is stirred for 8 hr at room
temperature. Filtration through Celite is followed by cooling of the stirred filtrate in an ice bath withacidification to pH 1 (dropwise addition of concentrated hydrochloric acid). The tan solid is isolated byfiltration and dried under vacuum at room temperature. On the average, the yield is 52–55 g (10–11%)
but can vary from 42 to 68 g (8–13% yield) (Note 13).

2. Notes
1. A paste made from a 1 : 1 mixture of mineral oil and silicone grease is used to lubricate the stirrer.
2. Prepurified argon (Linde) can be used with no further treatment.
3. Dry sodium hydride is available from Aldrich Chemical Company, Inc., as a fine powder. In multipleruns, it is most convenient to weigh the bulk reagent into 100-g (one reaction) lots. Extreme care should
be used in handling this moisture-sensitive, flammable solid.
4. Tetrahydrofuran is distilled from calcium hydride and then from sodium–benzophenone immediately
prior to use.
5. This amount of cyclopentadiene can be prepared in 2–3 hr using any of a variety of procedures.3,4,5
6. The checkers transferred cyclopentadiene by using a stainless-steel cannula from a cooled (dry ice–methanol), 500-mL, round-bottomed flask to the reaction vessel.
7. The complex was purchased from Aldrich Chemical Company, Inc.
8. A bright emerald-green color (usually) develops as the addition proceeds. If the iodine is impure, abrown color develops with no decrease in yield.
9. While dimethyl acetylenedicarboxylate is available commercially, it is easily prepared by theprocedure of Huntress et al.6 Care should be taken with this compound as it is a severe lachrymator andvesicant.
10. A tan to white precipitate of sodium iodide forms and a gentle exotherm is observed.
11. This concentrate (a dark red oil) may be stored in a refrigerator if time does not permit further work.
12. While the Diels–Alder reaction affords a wide variety of products, all of the esters formed hydrolyze
faster than the desired internal adduct. The above hydrolysis removes all byproducts through base
extraction. The internal diester has spectral properties as follows: 1H NMR (CDCl3) δ: 2.50 (tt, 2 H, J =2.0, 4.3), 3.30 (dd, 4 H, J = 2.0, 4.3), 3.59 (s, 6 H), 6.07 (t, 4 H, J = 2.0); 13C NMR (CDCl3) δ: 51.5,

58.8, 64.6, 69.5, 132.7, 172.7.
13. Spectral properties of the diacid are as follows: 1H NMR (d6-DMSO) δ: 2.36 (tt, 2 H, J = 1.5, 4.1),
3.21 (dd, 4 H, J = 1.5, 4.1), 5.95 (t, 4 H, J = 1.7).

3. Discussion
The present procedure is a modification of the method previously reported.7 8 While the overall
yield is similar, the method described here is simpler in that it avoids a cumbersome transfer of thesodium cyclopentadienide solution.
The first step leading to 9,10-dihydrofulvalene is adapted from the earlier work of Matzner.9 The
utility of this thermally labile hydrocarbon ranges from its ability to engage in multiple [4+2]cycloadditions7,8,10 to its capacity for bonding to a pair of metal atoms.11 12 13 14 15
The product diacid has served as starting material for the synthesis of tetracyclo[7.2.1.04,11.06,10]
dodeca-2,7-diene-5,12-dione,16 17 C16-hexaquinacene,18 19 20 21 (Cs)-C17-heptaquinane derivatives,22 23 theparent dodecahedrane molecule,24 25 26 and a number of substituted dodecahedranes.27 28 29 30 31 32 33 34

References and Notes
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.

Department of Chemistry, Miami University, Oxford, OH 45056.
Department of Chemistry, The Ohio State University, Columbus, OH 43210.
Moffett, R. B. Org. Synth., Coll. Vol. IV 1963, 238.
Korach, M.; Nielsen, D. R.; Rideout, W. H. Org. Synth., Coll. Vol. V 1973, 414.
Magnusson, G. J. Org. Chem. 1985, 50, 1998.
Huntress, E. H.; Lesslie, T. E.; Bornstein, J. Org. Synth., Coll. Vol. IV 1963, 329.
Paquette, L. A.; Wyvratt, M. J. J. Am. Chem. Soc. 1974, 96, 4671;
Paquette, L. A.; Wyvratt, M. J.; Berk, H. C.; Moerck, R. E. J. Am. Chem. Soc. 1978, 100, 5845.
Matzner, E. A. Ph.D. Thesis, Yale University, New Haven, CT, 1958.
Wyvratt, M. J.; Paquette, L. A. Tetrahedron Lett. 1974, 2433.
Vollhardt, K. P. C.; Weidman, T. W. J. Am. Chem. Soc. 1983, 105, 1676; Vollhardt, K. P. C.;
Weidman, T. W. Organometallics 1984, 3, 82;
Drage, J. S.; Tilset, M.; Vollhardt, K. P. C.; Weidman, T. W. Organometallics 1984, 3, 812;
Drage, J. S.; Vollhardt, K. P. C. Organometallics 1985, 4, 191; Drage, J. S.; Vollhardt, K. P. C.
Organometallics 1986, 5, 280;
Tilset, M.; Vollhardt, K. P. C. Organometallics 1985, 4, 2230;
Boese, R.; Tolman, W. B.; Vollhardt, K. P. C. Organometallics 1986, 5, 582.
Paquette, L. A.; Nakamura, K.; Fischer, J. W. Tetrahedron Lett. 1985, 26, 4015;
Paquette, L. A.; Nakamura, K.; Engel, P. Chem. Ber. 1986, 119, 3782.
Paquette, L. A.; Snow, R. A.; Muthard, J. L.; Cynkowski, T. J. Am. Chem. Soc. 1978, 100, 1600;
Paquette, L. A.; Snow, R. A.; Muthard, J. L.; Cynkowski, T. J. Am. Chem. Soc. 1979, 101, 6991;
Osborn, M. E.; Kuroda, S.; Muthard, J. L.; Kramer, J. D.; Engel, P.; Paquette, L. A. J. Org.
Chem. 1981, 46, 3379;Christoph, G. G.; Muthard, J. L.; Paquette, L. A.; Bohm, M. C.; Gleiter, R. J. Am. Chem. Soc.
1978, 100, 7782.
Sobczak, R. L.; Osborn, M. E.; Paquette, L. A. J. Org. Chem. 1979, 44, 4886;
Osborn, M. E.; Pegues, J. F.; Paquette, L. A. J. Org. Chem. 1980, 45, 167.
Ternansky, R. J.; Balogh, D. W.; Paquette, L. A. J. Am. Chem. Soc. 1982, 104, 4503;
Paquette, L. A.; Ternansky, R. J.; Balogh, D. W.; Kentgen, G. J. Am. Chem. Soc. 1983, 105,5446;
Gallucci, J. C.; Doecke, C. W.; Paquette, L. A. J. Am. Chem. Soc. 1986, 108, 1343.
Paquette, L. A.; Balogh, D. W.; Usha, R.; Kountz, D.; Christoph, G. G. Science 1981, 211, 575;
Paquette, L. A.; Balogh, D. W. J. Am. Chem. Soc. 1982, 104, 774;
Christoph, G. G.; Engel, P.; Usha, R.; Balogh, D. W.; Paquette, L. A. J. Am. Chem. Soc. 1982,104, 784;30. Paquette, L. A.; Ternansky, R. J.; Balogh, D. W. J. Am. Chem. Soc. 1982, 104, 4502;
31. Paquette, L. A.; Balogh, D. W.; Ternansky, R. J.; Begley, W. J.; Banwell, M. G. J. Org. Chem.
1983, 48, 3282;
32. Paquette, L. A.; Ternansky, R. J.; Balogh, D. W.; Taylor, W. J. J. Am. Chem. Soc. 1983, 105,5441;
33. Paquette, L. A.; Miyahara, Y.; Doecke, C. W. J. Am. Chem. Soc. 1986, 108, 1716;
34. Paquette, L. A.; Miyahara, Y. J. Org. Chem. 1987, 52, 1265.

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);(Registry Number)petroleum ether
9,10-Dihydrofulvalene
activated charcoal
C16-hexaquinacene(Cs)-C17-heptaquinane
dodecahedrane
Dry Icehydrochloric acid (7647-01-0)
acetic acid (64-19-7)
methanol (67-56-1)
ether (60-29-7)
sodium carbonate (497-19-8)
oxygen (7782-44-7)
sodium thiosulfate (7772-98-7)
iodine (7553-56-2)
potassium hydroxide (1310-58-3)
Benzophenone (119-61-9)
sodium (13966-32-0)
sodium iodide (7681-82-5)

magnesium sulfate (7487-88-9)
Tetrahydrofuran (109-99-9)
sodium hydride (7646-69-7)
CYCLOPENTADIENE (542-92-7)
argon (7440-37-1)
Dimethyl acetylenedicarboxylate (762-42-5)
calcium hydride (7789-78-8)
sodium cyclopentadienide (4984-82-1)
3,3a,3b,4,6a,7a-Hexahydro-3,4,7-metheno-7H-cyclopenta[a]pentalene-7,8-dicarboxylic acid,
3,4,7-Metheno-7H-cyclopenta[a]pentalene-7,8-dicarboxylic acid, 3,3a,3b,4,6a,7a-hexahydro (61206-255)
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