Transacetalization of 1,3-dioxane with acylium and sulfinyl cations in the gas phase

Abstract

Transacetalization occurs extensively in gas phase ion–molecule reactions of 1,3-dioxane with a variety of acylium ions [R–C⁺[double bond, length half m-dash]O; R = CH₃, C₂H₅, Ph, CH₃O, Cl, CH₂[double bond, length half m-dash]CH, (CH₃)₂N] and a sulfur analogue, the thioacetyl ion CH₃–C⁺[double bond, length half m-dash]S. Six-membered 1,3-dioxanylium ions and analogues, i.e. cyclic `ionic (thio)ketals', are formed, as evidenced by pentaquadrupole triple-stage collision-dissociation mass spectra and MP2/6–311G(d,p)//6–311G(d,p) + ZPE ab initio calculations, as well as by <sup>18</sup>O labelling experiments. Transacetalization with 1,3-dioxane is not a general reaction for sulfinyl cations (R–S<sup>+</sup>[double bond, length half m-dash]O). They react either moderately (CH<sub>3</sub>–S<sup>+</sup>[double bond, length half m-dash]O) or extensively (CH<sub>2</sub>[double bond, length half m-dash]CH–S<sup>+</sup>[double bond, length half m-dash]O) by transacetalization, form abundant intact adducts (Ph–S<sup>+</sup>[double bond, length half m-dash]O) or undergo mainly proton transfer and/or hydride abstraction reactions (Cl–S<sup>+</sup>[double bond, length half m-dash]O, CH<sub>3</sub>O–S<sup>+</sup>[double bond, length half m-dash]O and C<sub>2</sub>H<sub>5</sub>O–S<sup>+</sup>[double bond, length half m-dash]O). Competitive MS<sup>2</sup> experiments are employed to compare the transacetalization reactivity of different acylium ions, and that of two cyclic neutral acetals, that is 1,3-dioxane and 1,3-dioxolane. All the cyclic `ionic ketals' dissociate exclusively under low-energy collision conditions to regenerate the original reactant ion species, a simple dissociation chemistry that is amply demonstrated to be a very general characteristic of the transacetalization products. The cyclic `ionic thioketal' formed in transacetalization with CH₃–C⁺[double bond, length half m-dash]S is found, however, to dissociate exclusively to the oxygen analogue ion CH₃–C⁺[double bond, length half m-dash]O, a triple-stage mass spectrometric (MS³) experiment that constitutes a novel gas-phase strategy for conversion of thioacylium ions into acylium ions.

References

1. F. A. Carey and R. J. Sunderberg, Advanced Organic Chemistry, Plenum Press, New York, 1984, 2nd edn..
2. H. Kunz, in Comprehensive Organic Synthesis, ed. B. M. Trost and I. Fleming, Pergamon Press, New York, 1991, vol. 59, p. 659.
3. (a) D. A. Chatfield and M. M. Bursey, J. Am. Chem. Soc., 1976, 98, 6492; (b) R. H. Staley, R. D. Wieting and J. L. Beauchamp, J. Am. Chem. Soc., 1977, 99, 5964; (c) M. Kumakura and T. Sigiura, J. Phys. Chem., 1978, 82, 639; (d) C. Sparapani and M. Speranza, J. Am. Chem. Soc., 1980, 102, 3120; (e) J. K. Kim and M. C. Caserio, J. Am. Chem. Soc., 1982, 104, 4624; (f) M. Attinà and F. Cacace, J. Am. Chem. Soc., 1983, 105, 1122; (g) M. C. Caserio and J. K. Kim, J. Am. Chem. Soc., 1983, 105, 6896; (h) C. Paradisi, H. Kenttämaa, Q. T. Le and M. C. Caserio, Org. Mass Spectrom., 1988, 23, 521; (i) N. A. Rahman, C. L. Fisher and M. C. Caserio, Org. Mass Spectrom., 1988, 23, 517; (j) M. N. Eberlin, T. K. Majumdar and R. G. Cooks, J. Am. Chem. Soc., 1992, 114, 2884; (k) M. N. Eberlin and R. G. Cooks, J. Am. Chem. Soc., 1993, 115, 9226; (l) T. Kotiaho, M. N. Eberlin, B. J. Shay and R. G. Cooks, J. Am. Chem. Soc., 1993, 115, 1004; (m) C. S. Creaser and B. L. Williamson, J. Chem. Soc., Perkin Trans. 2, 1996, 427.
4. (a) M. N. Eberlin and R. G. Cooks, Org. Mass Spectrom., 1993, 28, 679; (b) A. Leinonen and P. Vainotalo, Org. Mass Spectrom., 1994, 29, 295; (c) P. Vainiotalo, L. A. B. Moraes, F. C. Gozzo and M. N. Eberlin, Proc. 44th ASMS Conference on Mass Spectrometry and Allied Topics, 1996, 453; (d) L. A. B. Moraes, F. C. Gozzo, M. N. Eberlin and P. Vainiotalo, J. Org. Chem., 1997, 62, 5096.
5. F. C. Gozzo, A. E. P. M. Sorrilha and M. N. Eberlin, J. Chem. Soc., Perkin Trans. 2, 1996, 587.
6. H. Kunz, in Comprehensive Organic Synthesis, ed. B. M. Trost and I. Fleming, Pergamon Press, New York, 1991, vol. 59, p. 659.
7. V. F. Juliano, F. C. Gozzo, M. N. Eberlin, C. Kascheres and C. L. Lago, Anal. Chem., 1996, 68, 1328.
8. L. A. B. Moraes, R. S. Pimpim and M. N. Eberlin, J. Org. Chem., 1996, 61, 8726.
9. (a) J. C. Schwartz, K. L. Shey and R. G. Cooks, Int. J. Mass Spectrom. Ion Processes, 1990, 101, 1; (b) J. C. Schwartz, A. P. Wade, C. G. Enke and R. G. Cooks, Anal. Chem., 1990, 62, 1809; (c) M. N. Eberlin, Mass Spectrom. Rev., in the press.
10. For details and recent examples of the application of pentaquadrupole mass spectrometry to the study of gas-phase ion–molecule reactions see ref. 9(c) and: (a) M. N. Eberlin, T. Kotiaho, B. J. Shay, S. S. Yang and R. G. Cooks, J. Am. Chem. Soc., 1994, 116, 2457; (b) M. N. Eberlin, N. H. Morgon, S. S. Yang, B. J. Shay and R. G. Cooks, J. Am. Soc. Mass Spectrom., 1995, 6, 1; (c) F. C. Gozzo and M. N. Eberlin, J. Am. Soc. Mass Spectrom., 1995, 6, 554; (d) F. C. Gozzo and M. N. Eberlin, J. Mass Spectrom., 1995, 30, 1553; (e) A. E. P. M. Sorrilha, F. C. Gozzo, R. S. Pimpim and M. N. Eberlin, J. Am. Soc. Mass Spectrom., 1996, 7, 1126; (f) M. N. Eberlin, A. E. P. M. Sorrilha, R. S. Pimpim and F. C. Gozzo, J. Am. Chem. Soc., 1997, 119, 00.
11. GAUSSIAN 94, Revision B.3, M. J. Frisch, G. W. Trucks, H. B. Schlegel, P. M. W. Gill, B. G. Johnson, M. A. Robb, J. R. Cheeseman, T. Keith, G. A. Petersson, J. A. Montgomery, K. Raghavachari, M. A. Al-Laham, V. G. Zakrzewski, J. V. Ortiz, J. B. Foresman, C. Y. Peng, P. Y. Ayala, W. Chen, M. W. Wong, J. L. Andres, E. S. Replogle, R. Gomperts, R. L. Martin, D. J. Fox, J. S. Binkley, D. J. Defrees, J. Baker, J. P. Stewart, M. Head-Gordon, C. Gonzalez and J. A. Pople, Gaussian, Inc., Pittsburgh PA, 1995.
12. (a) W. J. Hehre, R. Ditchfield and J. A. Pople, J. Chem. Phys., 1972, 56, 2257; (b) P. C. Hariharan and J. A. Pople, Theor. Chem. Acta, 1973, 72, 650; (c) M. S. Gordon, Chem. Phys. Lett., 1980, 76, 163; (d) M. J. Frisch, J. A. Pople and J. S. Binkley, J. Chem. Phys., 1984, 80, 3265.
13. C. Møller and M. S. Plesset, Phys. Rev., 1934, 46, 618.