Premium
Influence of the Solvent Polarity on the Stereoselectivity of the Uncatalyzed [4+2] Cycloaddition of Cyclopentadiene to N , N ′‐Fumaroyldi[(2 R )‐borane‐10,2‐sultam]
Author(s) -
Chapuis Christian,
Kucharska Anna,
Rzepecki Piotr,
Jurczak Janusz
Publication year - 1998
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19981216)81:12<2314::aid-hlca2314>3.0.co;2-i
Subject(s) - chemistry , cyclopentadiene , cycloaddition , stereoselectivity , diastereomer , medicinal chemistry , conformational isomerism , solvent effects , solvent , organic chemistry , stereochemistry , computational chemistry , catalysis , molecule
A correlation between the solvent polarity and the logarithm of the diastereoisomer ratio (dr) was found for the uncatalyzed [4+2] cycloaddition of cyclopentadiene to N , N ′‐fumaroyldi[(2 R )‐bornane‐10,2‐sultam]. Using the Abboud‐Abraham‐Kamlet‐Taft parameters, predictive values for this method, allowed an optimum diastereoisomeric excess (de) of 96% (EtOH, −78°). A similar diastereoselectivity was achieved using 5 M LiClO 4 /Et 2 O or H 2 O/ β ‐cyclodextrin, and the influence of supercritical CO 2 is also reported. Selective cycloadditions of apolar diene in polar solvents are entropically favored by the greater dipole moment of the N‐ enoylcamphorsultam syn ‐s‐ cis conformers and of the C( α )‐ re transition states. Implications on the stereochemical course of the reaction are discussed.