Ortho-[2,3]-wittig rearrangement of benzyl propargyl ethers: Striking preference over the competing [1,2]-wittig shift

Chemistry Letters

Volumn , Issue 12, 2000, Pages 1394-1395

  Tomooka, Katsuhiko ^a   Harada, Manabu ^a   Hanji, Takayuki ^a   Nakai, Takeshi ^a  

^a TOKYO INSTITUTE OF TECHNOLOGY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0034345718     PISSN: 03667022     EISSN: None     Source Type: Journal    
DOI: 10.1246/cl.2000.1394     Document Type: Article

References (18)

1. Reviews: a) T. Nakai and K. Mikami, Chem. Rev., 86, 885 (1986).
2. b) T. Nakai and K. Mikami, Org. React., 46, 105 (1994).
3. a) G. Wittig and L. Lmann, Liebigs Ann. Chem., 550, 260 (1942).
4. b) H. Felkin and C. Frajerman, Tetrahedron Lett., 1977, 3485.
5. c) K. Tomooka, K. Yamamoto, and T. Nakai, Angew. Chem., Int. Ed., 38, 3741 (1999).
6. a) K. Tomooka, T. Igarashi, and T. Nakai, Tetrahedron, 50, 5927 (1994).
7. b) K. Tomooka, H. Yamamoto, and T. Nakai, Liebigs Ann./Recueil, 1997, 1275.
8. U. Schölkopf, K. Fellenberger, and M. Rizk, Liebigs Ann. Chem., 734, 106 (1970). In this paper, any mechanistic reason for the exceptional periselectivity has not been given. Note that a similar [2,3]-Wittig shift has been reported in the carbanion rearrangement of several 3-furylmethyl ethers: B. Cazes and S. Julia, Synth. Commun., 1977, 113; M. Tsubuki, H. Okita, and T. Honda, J. Chem. Soc., Chem. Commun., 1995, 2135.
9. U. Schölkopf, K. Fellenberger, and M. Rizk, Liebigs Ann. Chem., 734, 106 (1970). In this paper, any mechanistic reason for the exceptional periselectivity has not been given. Note that a similar [2,3]-Wittig shift has been reported in the carbanion rearrangement of several 3-furylmethyl ethers: B. Cazes and S. Julia, Synth. Commun., 1977, 113; M. Tsubuki, H. Okita, and T. Honda, J. Chem. Soc., Chem. Commun., 1995, 2135.
10. U. Schölkopf, K. Fellenberger, and M. Rizk, Liebigs Ann. Chem., 734, 106 (1970). In this paper, any mechanistic reason for the exceptional periselectivity has not been given. Note that a similar [2,3]-Wittig shift has been reported in the carbanion rearrangement of several 3-furylmethyl ethers: B. Cazes and S. Julia, Synth. Commun., 1977, 113; M. Tsubuki, H. Okita, and T. Honda, J. Chem. Soc., Chem. Commun., 1995, 2135.
11. K. Brickmann and R. Brkner, Chem. Ber., 126, 1227 (1993).
12. Review: I. Markó, "Comprehensive Organic Synthesis,"ed. by G. Pattenden, Pergamon Press, Oxford (1991), Vol. 3, p. 913.
13. Note that the ortho-[2,3]-Wittig shift requires benzylic ethers as substrates which could be lithiated on the benzyloxy-bearing carbon preferentially over the benzylic carbon. In this regard, allyl benzyl ether, e.g., is not qualified as an substrate, since its lithiation occurs exclusively on the benzylic carbon.
14. 2Ph) and δ 4.53-4.59 (m, CH-OH); 5a, δ 10.01 (d, CHO), and δ 6.32 (dt, =CHCHO).
15. 1H NMR spectra of products 3b, 4b, and 5b are in accord with the assigned structures.
16. 2C≡), and δ 2.08 (t, HC≡).
17. 1H NMR spectra of products 3d, 4d, and 6d are in accord with the assigned structures.
18. 2Ph) and δ 1.56 (s, Me-C-OH); 6e, δ 4.52 (d, CH-OH) and δ 1.11 (d, Me-CH).