Transannular ring closure of 10-membered cyclic diynes: model calculations
The transannular ring closure reaction of the 10-membered cyclic diynes cyclodeca-1,6-diyne (9a), 1,6-diazacyclodeca-3,8-diyne (9b), and 1,6-dioxacyclodeca-3,8-diyne (9c) to the corresponding bicyclo[4.4.0]deca-1,6-diene-2,7-diyl systems (11a−c) has been investigated using quantum mechanical methods...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
05/01/1999
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| In: |
Journal of the American Chemical Society
Year: 1999, Volume: 121, Issue: 19, Pages: 4664-4668 |
| ISSN: | 1520-5126 |
| DOI: | 10.1021/ja980468q |
| Online Access: | Resolving-System, lizenzpflichtig, Volltext: https://doi.org/10.1021/ja980468q Verlag, lizenzpflichtig, Volltext: https://pubs.acs.org/doi/10.1021/ja980468q 
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| Author Notes: | Gebhard Haberhauer and Rolf Gleiter |
| Summary: | The transannular ring closure reaction of the 10-membered cyclic diynes cyclodeca-1,6-diyne (9a), 1,6-diazacyclodeca-3,8-diyne (9b), and 1,6-dioxacyclodeca-3,8-diyne (9c) to the corresponding bicyclo[4.4.0]deca-1,6-diene-2,7-diyl systems (11a−c) has been investigated using quantum mechanical methods. To optimize the geometries of the ground states, 9a−c, the transition states, 10a−c, and the intermediates, 11a−c, we employed the CASSCF(8,8)/6-31G* procedure. The inclusion of dynamic correlation (CASPT2[0] and CASPT2[g1]) approximations was necessary to reproduce the thermodynamic parameters obtained experimentally for 9a → 11a. Our calculations reveal that the activation energy for the ring closures 9 → 11 depends on the distance between the triple bonds. The alternative of the ring closure of 9a to bicyclo[5.3.0]deca-1,6-diene-2,6-diyl (13a) is predicted to occur at a higher activation energy (ca. 7 kcal/mol) than that for ring closure to 11a. A comparison with the Bergman cyclization reveals late transition states for 9a−c → 11a−c, in which the conjugation of the developing 4π system plays no role. |
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| Item Description: | Gesehen am 30.10.2020 |
| Physical Description: | Online Resource |
| ISSN: | 1520-5126 |
| DOI: | 10.1021/ja980468q |