Carboxy(vinyl)ketene intermediates in the thermolysis of methylthio- and methoxy-substituted Meldrum’s acid derivatives

Abstract

Methylthio- and methoxy-substituted carboxy(vinyl)ketenes 10 and 16a have been identified by Ar matrix isolation FTIR spectroscopy following flash vacuum thermolysis (FVT) of Meldrum’s acid derivatives 7 and 13a. Methylthio(methyl)methyleneketene 9 and alkoxy(methyl)methyleneketene 15 are formed concurrently at high FVT temperatures. The alkoxy(methyl)methyleneketenes 15 do not isomerise to alkoxy(vinyl)ketenes 18, which have been generated and identified in other reactions. Ethoxy(methyl)methyleneketene 15b readily eliminates ethene in a retro-ene type reaction to produce acetylketene 22. Ketenes 15 react with alcohols and amines to produce 3-alkoxybutenoic acid derivatives 21.

References

1. (a) G. Gross, C. Wentrup, H.-M. Berstermann and P. Lorencak, J. Org. Chem., 1985, 50, 2877; (b) S. Mohmand, T. Hirabayashi and H. Bock, Chem. Ber., 1981, 114, 2609.
2. C. Wentrup and P. Lorencak, J. Am. Chem. Soc., 1988, 110, 1880.
3. Review of α-oxoketones: C. Wentrup, W. Heilmayer and G. Kollenz, Synthesis, 1994, 1219.
4. (a) A. Ben Cheik, J. Chuche, N. Manisse, J. C. Pommelet, K.-P. Netsch, P. Lorencak and C. Wentrup, J. Org. Chem., 1991, 56, 970; (b) F. Chuburu, S. Lacombe, G. Pfister-Guillouzo and C. Wentrup, New J. Chem., 1994, 18, 879.
5. (a) P. Lorencak, J. C. Pommelet, J. Chuche and C. Wentrup, J. Chem. Soc., Chem. Commun., 1986, 369; (b) C. Wentrup, P. Kambouris, R. A. Evans, D. Owen, G. Macfarlane, J. Chuche, J. C. Pommelet, A. Ben Cheikh, M. Plisnier and R. Flammang, J. Am. Chem. Soc., 1991, 113, 3130.
6. A. Ben Cheikh, H. Dhimane, J. C. Pommelet and J. Chuche, Tetrahedron Lett., 1988, 29, 5919.
7. F. Chuburu, S. Lacombe, G. Pfister-Guillouzo, A. Ben Cheikh, J. Chuche and J. C. Pommelet, J. Am. Chem. Soc., 1991, 113, 1954.
8. F. Chuburu, S. Lacombe and G. Pfister-Guillouzo, J. Org. Chem., 1991, 56, 3447.
9. X. Huang and B.-C. Chen, Synthesis, 1987, 480.
10. (a) C. V. Berney, J. Chem. Phys., 1970, 53, 1713; (b) D. E. Milligan and M. E. Jacox, J. Chem. Phys., 1971, 54, 927.
11. See for instance: (a) R. F. C. Brown, F. W. Eastwood and K. J. Harrington, Aust. J. Chem., 1974, 27, 2373; (b) R. F. C. Brown, F. W. Eastwood, N. R. Browne, K. J. Coulston, M. J. Irvine, A. D. E. Pullin and U. E. Wiersum, Aust. J. Chem., 1989, 42, 1321.
12. G. A. Hunter and H. McNab, J. Chem. Soc., Chem. Commun., 1990, 375; G. A. Hunter and H. McNab, J. Chem. Soc., Perkin Trans. 1, 1995, 1209.
13. Above 700 °C, two new bands were observed at 2121 and 2111 cm^–1, increasing in intensity with the temperature. Further investigation will be needed in order to identify the carrier of these absorptions, which is not 18.
14. (a) A. D. Becke, J. Chem. Phys., 1993, 98, 5648; (b) C. Lee, W. Yang and R. G. Parr, Phys. Rev., 1988, B37, 785.
15. E. Taskinen and V.-M. Mukkala, Tetrahedron, 1982, 38, 613.
16. (a) Y. Chiang, H.-X. Guo, A. J. Kresge and O. S. Tee, J. Am. Chem. Soc., 1996, 118, 3386; (b) J. Frey and Z. Rappoport, J. Am. Chem. Soc., 1996, 118, 5182; (c) D. J. Graham, S. M. Hurst and J.-C. Luo, J. Phys. Chem., 1995, 99, 1115; (d) M. T. Nguyen, D. Sengupta, G. Raspoet and L. G. Vanquickenborne, J. Phys. Chem., 1995, 99, 11 883; (e) X. Duan and M. Page, J. Am. Chem. Soc., 1995, 117, 5114.
17. (a) H. Bibas, M. W. Wong and C. Wentrup, Chem. Eur. J., 1997, 3, 237; (b) B. E. Fulloon, D. W. J. Moloney, H. Bibas, M. W. Wong and C. Wentrup, Pure Appl. Chem., 1996, 68, 891; (c) H. Bibas, M. W. Wong and C. Wentrup, J. Am. Chem. Soc., 1995, 117, 9583.
18. H. Bibas, R. Koch and C. Wentrup, submitted for publication in J. Org. Chem.
19. s-cis-Acetylketene: 3095, 2148, 2143, 1681, 1378, 1345, 1168 cm^–1. s-trans-Acetylketene: 3083, 2137, 2133, 1699, 1343, 1221 cm^–1.
20. (a) C. O. Kappe, M. W. Wong and C. Wentrup, J. Org. Chem., 1995, 60, 1686; (b) R. H. Zuhse, M. W. Wong and C. Wentrup, J. Phys. Chem., 1996, 100, 3917.
21. D. W. J. Moloney and C. Wentrup, J. Org. Chem., 1997, 62, 4240.
22. (a) M. W. Wong and C. Wentrup, unpublished results; (b) the G2(MP2,SVP) calculated relative energies of the ylides analogous to 12, formed by 1,4-H shifts in (MeX)CH=C=C=O are 173 (X = O), 96 (X = S) and 104 (X = NH) kJ mol^–1 above those of the methyleneketenes.
23. R. Flammang, D. Landu, S. Laurent, M. Barbieux-Flammang, C. O. Kappe, M. W. Wong and C. Wentrup, J. Am. Chem. Soc., 1994, 116, 2005; R. Flammang, S. Laurent, M. Barbieux-Flammang and C. Wentrup, Org. Mass Spectrom., 1993, 28, 1161.
24. M. W. Wong, Chem. Phys. Lett., 1996, 256, 391.
25. C. Wentrup, R. Blanch, H. Briehl and G. Gross, J. Am. Chem. Soc., 1988, 110, 1874.
26. G. A. Bihlmayer, G. Derflinger, J. Derkosch and O. E. Polansky, Monatsh. Chem., 1967, 98, 564.