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Nucleophilic Addition to C, C Double Bonds. Proximity and homoconjugative effects. Preliminary communication
Author(s) -
Pfund Rolland A.,
Ganter Camille
Publication year - 1979
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.19790620131
Subject(s) - chemistry , double bond , ether , olefin fiber , stereoselectivity , nucleophile , nucleophilic addition , stereochemistry , ring (chemistry) , medicinal chemistry , regioselectivity , base (topology) , organic chemistry , catalysis , mathematical analysis , mathematics
Proximity effects alone as well as in combination with electronic effects are responsible for the observed phenomenon of base‐catalyzed ether formation initiated by nucleophilic attack on a C, C double bond of the tricyclic olefin alcohols 1–10 (Scheme 1, Table 1) . With compounds 1–4 , bearing a keto group, formation of the ethers 11–14 proceeds through a corresponding homoenolate b (Scheme 2) as an intermediate. In one case such a species could be trapped as the methyl ether 21 (Scheme 3) . Special attention is given to the stereochemical course of the homoketonization. Ring opening in 21 under acidic conditions occurs regioselectively, however non‐stereoselectively (Scheme 3) . Full regio‐ and stereoselectivity (retention) is observed under basic conditions starting from the unsaturated keto alcohols 1 and 2 (Scheme 4) as well as from the keto ethers 11 and 12 (Scheme 5, Table 2) .