Abstract
Two alternative procedures, both starting from easily accessible tetramethylanthracenes
and employing the Diels-Alder addition as the key reaction step(s), have been examined
in the synthesis of the title compounds.
Key words
carboxylic acids - Diels-Alder reactions - oxidations - triptycenes - arynes
References
<A NAME="RT01907SS-1A">1a </A>
Holý P.
Závada J.
Císařová I.
Podlaha J.
Angew. Chem. Int. Ed.
1999,
38:
381
<A NAME="RT01907SS-1B">1b </A>
Holý P.
Sehnal P.
Tichý M.
Závada J.
Císařová I.
Tetrahedron: Asymmetry
2003,
14:
245
<A NAME="RT01907SS-1C">1c </A>
Holý P.
Kováč M.
Tichý M.
Závada J.
Buděšínský M.
Císařová I.
Tetrahedron: Asymmetry
2005,
16:
2031
<A NAME="RT01907SS-1D">1d </A>
Holý P.
Havlík M.
Tichý M.
Závada J.
Císařová I.
Collect. Czech. Chem. Commun.
2006,
71:
139
<A NAME="RT01907SS-2">2 </A>
Rybáček J.; Rybáčková, M.; Høj, M.; Holý, P.; Bělohradský, M.; Kilså, K.; Nielsen,
M. B., manuscript in preparation.
<A NAME="RT01907SS-3">3 </A>
Rybáčková M.
Bělohradský M.
Holý P.
Pohl R.
Závada J.
Synthesis
2006,
2039
<A NAME="RT01907SS-4">4 </A>
6a : 1 H NMR (400 MHz, CDCl3 ): δ = 1.84 (s, 6 H), 2.35 (s, 6 H), 4.77 (s, 2 H), 6.98 (m, 2 H), 7.29 (m, 2 H),
7.42 (s, 2 H), 7.50 (s, 2 H). 6b : 1 H NMR (400 MHz, CDCl3 ): δ = 1.83 (s, 6 H), 2.16 (s, 6 H), 2.34 (s, 6 H), 4.70 (s, 2 H), 7.10 (s, 2 H),
7.40 (s, 2 H), 7.46 (s, 2 H).
<A NAME="RT01907SS-5">5 </A>
Similar problems with regioselectivity are common in aryne addition to anthracenes,
cf. ref 6. Steric hindrance to aryne approach due to methyls may account well for
the different outcomes obtained with anthracenes 1 and 4 in Scheme
[1 ]
.
<A NAME="RT01907SS-6">6 </A>
Klanderman BH.
Criswell TR.
J. Org. Chem.
1969,
34:
3426
<A NAME="RT01907SS-7A">7a </A>
Butler DN.
Snow RA.
Can. J. Chem.
1975,
53:
256
<A NAME="RT01907SS-7B">7b </A>
Ihmels H.
Schneider M.
Waidelich M.
Org. Lett.
2002,
4:
3247
<A NAME="RT01907SS-8">8 </A>
Hart H.
Bashir-Hashemi A.
Luo J.
Meador MA.
Tetrahedron
1986,
42:
1641
<A NAME="RT01907SS-9">9 </A>
Chan T.-L.
Mak TCW.
Poon C.-D.
Wong HNC.
Jia JH.
Wang LL.
Tetrahedron
1986,
42:
655.
<A NAME="RT01907SS-10">10 </A>
Hinshaw JC.
Org. Prep. Proced. Int.
1972,
4:
211
<A NAME="RT01907SS-11">11 </A>
Wilcox CF.
Farley EN.
J. Am. Chem. Soc.
1984,
106:
7195
<A NAME="RT01907SS-12">12 </A>
Baker BR.
Schaub RE.
Joseph JP.
McEvoy FJ.
Williams JH.
J. Org. Chem.
1952,
17:
149
<A NAME="RT01907SS-13">13 </A>
Skvarchenko VR.
Shil’nikova AG.
Zakharova G.
Levina RY.
Zh. Org. Khim.
1970,
6:
174 ; Chem. Abstr. 1970, 73, 3692