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Stereo and Face Selectivity in Cycloadditions of 1,2,3‐Trichloro‐3‐fluorocyclopropenes to Acyclic Dienes and Furans
Author(s) -
Müller Paul,
Bernardinelli Gérald,
Pfyffer Jean,
Schaller JeanPierre
Publication year - 1991
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/hlca.19910740510
Subject(s) - chemistry , cyclopropane , cycloaddition , selectivity , ring (chemistry) , stereochemistry , adduct , medicinal chemistry , organic chemistry , catalysis
The stereo and face selectivities of the cycloaddition of 1,2,3‐trichloro‐3‐fluorocyclopropene ( 1a ) with acyclic dienes and furans has been re‐investigated by X‐ray determination and correlation of 19 F‐NMR data. The isolated adducts of dienes exclusively have exo ‐configuration, and exo ‐Configuration predominates with furans. The Cl substituents of the resulting cyclopropane ring are cis ‐oriented. The face selectivity of the reaction with both types of substrates is attributed to electrostatic interactions between the F and the bridgehead Cl substituents, which destabilize the F‐ cis ‐transition state ( 13 (F‐ cis )) over 13 (F‐ trans ).