Enantioselective and Structure-Selective Diels-Alder Reactions of Unsymmetrical Quinones Catalyzed by a Chiral Oxazaborolidinium Cation. Predictive Selection Rules

Journal of the American Chemical Society

Volumn 126, Issue 15, 2004, Pages 4800-4802

  Ryu, Do Hyun ^a   Zhou, Gang ^a   Corey, E J ^a  

^a HARVARD UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CATION; COORDINATION COMPOUND; OXAZABOROLIDINE DERIVATIVE; QUINONE DERIVATIVE;

ARTICLE; CATALYSIS; CATALYST; CHEMICAL BOND; CHEMICAL STRUCTURE; CHIRALITY; DIELS ALDER REACTION; ELECTRON; ENANTIOSELECTIVITY; REACTION ANALYSIS; SYNTHESIS;

EID: 1842841091     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja049323b     Document Type: Article

References (11)

1. Ryu, D. H.; Corey, E. J. J. Am. Chem. Soc. 2003, 125, 6388-6390.
2. Zhou, G.; Hu, Q.-Y.; Corey, E. J. Org. Lett. 2003, 5, 3979-3982.
3. Ryu, D. H.; Lee, T. W.; Corey, E. J. J. Am. Chem. Soc. 2002, 124, 9992-9993.
4. Corey, E. J.; Shibata, T.; Lee, T. W. J. Am. Chem. Soc. 2002, 124, 3808-3809.
5. For a recent review of this area, see: Corey, E. J. Angew. Chem., Int. Ed. 2002, 41, 1650-1667.
6. For background literature, see: Breuning, M.; Corey, E. J. Org. Lett. 2001, 3, 1559-1562.
7. Corey, E. J.; Lee, T. W. J. Chem. Soc., Chem. Commun. 2001, 1321-1329.
8. Diels-Alder reaction of 2 with the methoxy analogue of quinone 3 and catalyst 1 was less regioselective and afforded the 7-methoxy analogue of 4 and the 6-methoxy regioisomer in a ratio of 76:24. The lower selectivity in this case relative to 4 is understandable in view of the stronger π-electron donation from OTBS vs methoxy in the quinone substrates.
9. As is well known, thermal quinone Diels-Alder reactions with unsymmetrical components are relatively nonregioselective. For instance, for the case of Table 1, entry 2, the thermal reaction at 110 °C affords a 43: 56 mixture of (±)-regioisomers with that shown in Table I being the minor component.
10. 4-molecular sieves system is a known catalyst for enantioselective Diels-Alder addition of 1,3-dienes to quinones; for a leading reference, see: White, J. D.; Choi, Y. Helv. Chim. Acta, 2002, 85, 4306-4327. In addition, pybox lanthanide catalysts have recently been applied to quinones having a methoxycarbonyl substituent; see: Evans, D. A.; Wu, J. J. Am. Chem. Soc. 2003, 125, 10162-10163.
11. 4-molecular sieves system is a known catalyst for enantioselective Diels-Alder addition of 1,3-dienes to quinones; for a leading reference, see: White, J. D.; Choi, Y. Helv. Chim. Acta, 2002, 85, 4306-4327. In addition, pybox lanthanide catalysts have recently been applied to quinones having a methoxycarbonyl substituent; see: Evans, D. A.; Wu, J. J. Am. Chem. Soc. 2003, 125, 10162-10163.