One-pot synthesis of pyrroles through carbometalation reaction of zincated hydrazone with vinylstannane

Organic Letters

Volumn 1, Issue 10, 1999, Pages 1505-1507

  Nakamura, Masaharu ^a   Hara, Kenji ^a   Sakata, Go ^a   Nakamura, Eiichi ^a  

^a UNIVERSITY OF TOKYO   (Japan)

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[No Author keywords available]

Indexed keywords

EID: 0000401304     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol990911h     Document Type: Article

References (20)

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2. (b) Trofimov, B. A.; Mikhaleva, A. I. Heterocycles 1994, 37, 1193-1232.
3. (c) Enders, D.; Maassen, R.; Han, S.-H. Liebigs Ann. 1996, 1565-1574.
4. Metal homoenolates, Kuwajima, I.; Nakamura, E. In Comprehensive Organic Synthesis, Vol. 2; Trost, B. M., Fleming, I., Eds.; Pergamon Press: New York, 1991; Chapter 1.14. Nakamura, E.; Kuwajima, I. J. Am. Chem. Soc. 1977, 99, 7360-7361. Nakamura, E.; Kuwajima, I. J. Am. Chem. Soc. 1983, 105, 651-652.
5. Metal homoenolates, Kuwajima, I.; Nakamura, E. In Comprehensive Organic Synthesis, Vol. 2; Trost, B. M., Fleming, I., Eds.; Pergamon Press: New York, 1991; Chapter 1.14. Nakamura, E.; Kuwajima, I. J. Am. Chem. Soc. 1977, 99, 7360-7361. Nakamura, E.; Kuwajima, I. J. Am. Chem. Soc. 1983, 105, 651-652.
6. Metal homoenolates, Kuwajima, I.; Nakamura, E. In Comprehensive Organic Synthesis, Vol. 2; Trost, B. M., Fleming, I., Eds.; Pergamon Press: New York, 1991; Chapter 1.14. Nakamura, E.; Kuwajima, I. J. Am. Chem. Soc. 1977, 99, 7360-7361. Nakamura, E.; Kuwajima, I. J. Am. Chem. Soc. 1983, 105, 651-652.
7. Nakamura, E.; Kuwajima, I. J. Am. Chem. Soc. 1984, 106, 3368-3370. Nakamura, E.; Aoki, S.; Sekiya, K.; Oshino, H.; Kuwajima, I. J. Am. Chem. Soc. 1987, 109, 8056-8066.
8. Nakamura, E.; Kuwajima, I. J. Am. Chem. Soc. 1984, 106, 3368- 3370. Nakamura, E.; Aoki, S.; Sekiya, K.; Oshino, H.; Kuwajima, I. J. Am. Chem. Soc. 1987, 109, 8056-8066.
9. Nakamura, E.; Kubota, K. J. Org. Chem. 1997, 62, 792-793.
10. Kubota, K.; Nakamura, E. Angew. Chem., Int. Ed. Engl. 1997, 36, 2491-2493. Nakamura, E.; Sakata, G.; Kubota, K. Tetrahedron Lett. 1998, 39, 2157-2160.
11. Kubota, K.; Nakamura, E. Angew. Chem., Int. Ed. Engl. 1997, 36, 2491-2493. Nakamura, E.; Sakata, G.; Kubota, K. Tetrahedron Lett. 1998, 39, 2157-2160.
12. Nakamura, E.; Kubota, K.; Sakata, G. J. Am. Chem. Soc. 1997, 119, 5457-5458. Nakamura, E.; Kubota, K. Tetrahedron Lett. 1997, 38, 7099- 7102.
13. Nakamura, E.; Kubota, K.; Sakata, G. J. Am. Chem. Soc. 1997, 119, 5457-5458. Nakamura, E.; Kubota, K. Tetrahedron Lett. 1997, 38, 7099-7102.
14. 6 the rate of carbozincation reaction is considerably slower than that of vinylstannanes. In addition, the oxidative conversion of the resulting gem-Zn/Si dimetallic product to pyrrole was much less effective than the gem-Zn/Sn dimetallics. For a prior work on the oxygen oxidation of zinc-tin organometallics, see: Knochel, P.; Xiao, C.; Yeh, M. C. P. Tetrahedron Lett. 1988, 29, 6697-6700.
15. 2(0.40 mmol) at 0°C. The reaction mixture was cooled to -45°C and exposed to a dry oxygen atmosphere for 4.5 h. After removal of excess oxygen by degassing, the reaction mixture was stirred for 13 h at 0°C and then filtered through a pad of silica gel to afford a crude product as a colorless oil (214 mg). Purification on silica gel afforded the substituted pyrrole 4b (60 mg, 0.31 mmol) in 77% yield.
16. For theoretical analysis of regiochemistry of carbometalation, see: Nakamura, E.; Miyachi, Y.; Koga, N.; Morokuma, K. J. Am. Chem. Soc. 1992, 114, 6686-6692.
17. Unreacted vinylstannane was recovered quantitatively.
18. Syn stereochemistry of the hydrazone products tentatively assigned in our previous reports (refs 4-6) should be corrected to be anti. Note that the starting lithiated hydrazone is in syn stereochemistry, and it reacts with an alkyl halide with retention of the syn stereochemistry. Collum, D. B.; Kahne, D.; Gut, S. A.; DePue, R. T.; Mohamadi, F.; Wanat, R. A.; Clardy, J.; Van Duyne, G. J. Am. Chem. Soc. 1984, 106, 4865-4869.
19. A hydroperoxide, which formed through oxidation of the C-Zn bond of the Zn/Sn dimetallic species and subsequent hydrolysis, was obtained as a byproduct in ca. 20% yield.
20. Martinez, G. R.; Grieco, P. A.; Srinivasan, C. V. J. Org. Chem. 1981, 46, 3861-3763.