2. 3/25/2015 Baldwin's rules Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Baldwin's_rules 2/5
Baldwin dis/favoured ring closures
3 4 5 6 7
type exo end exo end exo end exo end exo end
tet ✓ ✓ ✓ ✗ ✓ ✗ ✓ ✗
trig ✓ ✗ ✓ ✗ ✓ ✗ ✓ ✓ ✓ ✓
dig ✗ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓ ✓
The rules apply when the nucleophile can attack the bond in question in an ideal angle. These angles are
180° (Walden inversion) for exotet reactions, 109° (Bürgi–Dunitz angle) for exotrig reaction and 120° for
endodig reactions. Angles for nucleophilic attack on alkynes were reviewed and redefined recently.[3] The
"acute angle" of attack postulated by Baldwin was replaced with a trajectory similar to the Bürgi–Dunitz
angle.[4]
Contents
1 Applications
2 Rules for enolates
3 Exceptions
4 References
Applications
In one study, sevenmembered rings were constructed in a tandem 5exodig addition reaction / Claisen
rearrangement:[5]
A 6endodig pattern was observed in an allene alkyne 1,2addition / Nazarov cyclization tandem
catalysed by a gold compound:[6]
4. 3/25/2015 Baldwin's rules Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Baldwin's_rules 4/5
References
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1. Baldwin, J. E., Rules for Ring Closure, J. Chem. Soc., Chem. Commun. 1976, 734. doi:10.1039/C39760000734
(https://dx.doi.org/10.1039%2FC39760000734)(Open access)
2. Baldwin, J. E. et al. (1977). "Rules for Ring Closure: Ring Formation by Conjugate Addition of Oxygen
Nucleophiles". J. Org. Chem. 42 (24): 3846. doi:10.1021/jo00444a011
(https://dx.doi.org/10.1021%2Fjo00444a011).
3. Gilmore, K.; Alabugin,I. V. Cyclizations of Alkynes: Revisiting Baldwin's Rules for Ring Closure. Chem. Rev.
2011. 111, 6513–6556. doi:10.1021/cr200164y (https://dx.doi.org/10.1021%2Fcr200164y)
4. Alabugin, I. Gilmore, K.;Manoharan, M. Rules for Anionic and Radical Ring Closure of Alkynes. J. Am.
Chem.Soc. 2011, 133, 1260812623, doi:10.1021/ja203191f (https://dx.doi.org/10.1021%2Fja203191f)
5. Li, X.; Kyne, R. E.; Ovaska, T. V. Synthesis of SevenMembered Carbocyclic Rings via a MicrowaveAssisted
Tandem Oxyanionic 5exo dig Cyclization−Claisen Rearrangement Process, J. Org. Chem., 2007, 72, 6624
doi:10.1021/jo0710432 (https://dx.doi.org/10.1021%2Fjo0710432)
6. GuanYou Lin, ChunYao Yang, and RaiShung Liu. GoldCatalyzed Synthesis of Bicyclo[4.3.0]nonadiene
Derivatives via Tandem 6endodig/Nazarov Cyclization of 1,6Allenynes J. Org. Chem. 2007, 72, 67536757
doi:10.1021/jo0707939 (https://dx.doi.org/10.1021%2Fjo0707939)
7. Overhand, Mark; Hecht, Sidney M. (1994). "A Concise Synthesis of the Antifungal Agent (+)Preussin". The
Journal of Organic Chemistry 59 (17): 4721. doi:10.1021/jo00096a007
(https://dx.doi.org/10.1021%2Fjo00096a007).
8. Baldwin, Jack E.; Kruse, Lawrence I. (1977). "Rules for ring closure. Stereoelectronic control in the endocyclic
alkylation of ketone enolates". Journal of the Chemical Society, Chemical Communications (7): 233.
doi:10.1039/C39770000233 (https://dx.doi.org/10.1039%2FC39770000233).
9. Baldwin, J (1982). "Rules for ring closure: application to intramolecular aldol condensations in polyketonic
substrates". Tetrahedron 38 (19): 2939. doi:10.1016/00404020(82)850230
(https://dx.doi.org/10.1016%2F00404020%2882%29850230).
10. M. B. Smith, J. March, March’s Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 6th ed.,
WileyInterscience, 2007, ISBN 9780471720911
11. J. Clayden, N. Greeves, S. Warren, Organic Chemistry, 2nd ed., OUP Oxford, 2012, ISBN 9780199270293
12. J. E. Baldwin, J. Cutting, W. Dupont, L. Kruse, L. Silberman, R. C. Thomas. J. Chem. Soc., Chem. Commun.,
1976, 736738. doi:10.1039/C39760000736 (https://dx.doi.org/10.1039%2FC39760000736)
13. Finding the right path: Baldwin "Rules for Ring Closure" and stereoelectronic control of cyclizations. Alabugin,
I. V.; Gilmore, K. Chem. Commun., 2013, 49, 11246 – 11250.
http://pubs.rsc.org/en/content/articlehtml/2013/cc/c3cc43872d