On the Generation and Trapping of N-Unsubstituted Pyrazole o-Quinodimethanes

Synlett

Volumn 1996, Issue 6, 1996, Pages 531-532

  Tomé, Augusto C ^a   Cavaleiro, José A S ^a   Storr, Richard C ^b  

^a UNIVERSITY OF AVEIRO   (Portugal)

^b UNIVERSITY OF LIVERPOOL   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0042969988     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-1996-5486     Document Type: Article

References (16)

1. Recent reviews on heteroaromatic o-quinodimethanes: a) Chou, T.-S. Reviews on Heteroatom Chem. 1993, 8, 65-104; b) Ando, K.; Takayama, H. Heterocycles, 1994, 37, 1417-1439.
2. Recent reviews on heteroaromatic o-quinodimethanes: a) Chou, T.-S. Reviews on Heteroatom Chem. 1993, 8, 65-104; b) Ando, K.; Takayama, H. Heterocycles, 1994, 37, 1417-1439.
3. a) Chaloner, L.; Crew, A.; Storr, R. C. Tetrahedron Letters, 1991, 32, 7609-12;
4. b) Chaloner, L.; Crew, A.; O'Neill, P.M; Storr, R. C. Tetrahedron 1992, 48, 8101-16.
5. a) Mitkidou, S.; Stephanidou-Stephanatou, J. Tetrahedron Letters, 1990, 31, 5197;
6. b) Mitkidou, S.; Stephanidou-Stephanatou, J.; Terzis, A.; Mertzanos, G. Tetrahedron, 1992, 48, 6059-68;
7. c) Mertzanos, G.; Alexandrou, N.; Tsoleridis, C; Mitkidou, S.; Stephanidou-Stephanatou, J. Heterocycles, 1994, 37, 967.
8. a) Chou, T.-S.; Chang, R.-C. J. Org. Chem., 1993, 58, 493-496;
9. b) Chou, T.-S.; Chang, R.-C. Heterocycles, 1993, 36, 2839-50;
10. c) Tso, H.-H.; Yang, N.-C.; Chang, Y.-M. J. Chem. Soc., Chem. Commun., 1995, 1349-50;
11. d) Tso, H.-H.; Chang, Y.-M.; Tsay, H. Synthetic Commun., 1996, 26, 569-576.
12. 2; v) mCPBA
13. +., 71), 177 (9), 149 (100), 134 (28), 124 (99), 109 (24), 91 (17), 77 (40), 65 (17). This is a single diastereoisomer and is assumed to have a cis ring fusion as expected from a concerted Diels-Alder addition (reference 2).
14. 2, MeOH; iv) mCPBA
15. General procedure: the sulfones (1 mmol) and the dienophile (2 mmol) were heated in toluene (or chlorobenzene) (5 ml) at reflux, under nitrogen atmosphere, for 3-6h. After cooling, the mixture was applied to the top of a column of silica and the unconsumed dienophile and the adduct were eluted with gradient mixtures of dichloromethane/ethyl acetate.
16. +., 30), 207 (25), 178 (38), 147 (16), 119 (100), 92(21), 65(17).