Diels-Alder reactions of vinylboranes: A computational study on the boronsubstituent effects

Arkivoc

Volumn 2003, Issue 10, 2003, Pages 556-565

  Silva, María A ^a   Pellegrinet, Silvina C ^b   Goodman, Jonathan M ^a  

^a UNIVERSITY OF CAMBRIDGE   (United Kingdom)

^b Facultad de Ciencias Naturales e Instituto M Lillo   (Argentina)

Author keywords

Computational study; Diels Alder reactions; Substituent effect; Vinylboranes

Indexed keywords

BORANE DERIVATIVE; BORON; CYCLOPENTADIENE DERIVATIVE; ISOPRENE; UNCLASSIFIED DRUG; VINYLBORANE;

ARTICLE; CHEMICAL STRUCTURE; DIELS ALDER REACTION; EXPERIMENT; ISOMERISM; STEREOCHEMISTRY; STEREOSPECIFICITY; SUBSTITUTION REACTION;

EID: 3242675051     PISSN: 14246376     EISSN: None     Source Type: Journal    
DOI: None     Document Type: Article

References (21)

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12. (c) Lee, C.; Yang, W.; Parr, R. Phys. Rev. B 1988, 37, 785. Hehre, W. J.; Radom, L.; Schleyer, P. v. R.; Pople, J. A. Ab Initio Molecular Orbital Theory; Wiley: New York, 1986.
13. Hehre, W. J.; Radom, L.; Schleyer, P. v. R.; Pople, J. A. Ab Initio Molecular Orbital Theory; Wiley: New York, 1986.
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15. Glendening, E. D.; Badelhoop, J. K.; Reed, A. E.; Carpenter, J. E.; Weinhold, F. NBO 4.M; Theoretical Chemistry Institute: University of Wisconsin, Madison, 1999.
16. Jaguar 4.2, Schrodinger, Inc., Portland, Oregon, 2000.
17. We named the transition states as follows: the number indicates the dienophile, i.e. 1 for dimethylvinylborane (1), 2 for vinyl-9-BBN (2), 3 for dichlorovinylborane (3) and 4 for trivinylborane (4). Then we added A for cyclopentadiene (5), B for (E)-1,3-pentadiene (trans-piperylene, 6) and C for 2-methylbutadiene (isoprene, 7). Finally, we used O, M and P for ortho, meta and para regiochemistry and N and X for endo and exo stereochemistry, respectively. For example, 3BMX is the transition structure corresponding to the reaction between dichlorovinylborane and trans-piperylene leading to the meta regioisomer with an exo stereochemistry.
18. -1. We also performed the thermochemical analysis for the reactions under study and calculated the relative free energies. These values were very similar to those corresponding to the zero-point corrected energies and led to comparable calculated ratios. This result suggests entropic effects in isomeric transition structures are uniform for these reactions, which is in accord with previous results.
19. Experimental ratios were taken from Refs. 3 and 4. For the reactions of vinyldimethylborane and trivinylborane with isoprene, we used the data obtained experimentally for myrcene, a diene structurally similar to isoprene.
20. Mackey, M. D.; Goodman, J. M. Chem. Comm. 1997, 2383.
21. The two conformations 4a and 4b for trivinylborane (4) were studied and no significant difference in energy (0.3 kcal/mol) was calculated. 4a is almost planar, 4b is less so.