ADDITIVE AND MEDIUM EFFECTS ON LEWIS ACID-PROMOTED CATIONIC PI-CYCLIZATIONS OF ALKENYLCYCLOPENTANE-1,3-DIONES AND ALKYNYLCYCLOPENTANE-1,3-DIONES

The effects of nucleophilic additives, Lewis and Bronsted acids, and solvents on BF3.Et(2)O-promoted cationic pi-cyclizations of alkynyl- and alkenylcyclopentane-1,3-diones are reported. The rates and selectivities of alkynyl dione cyclizations were significantly effected by the addition of external...

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Bibliographic Details
Published inJournal of organic chemistry Vol. 60; no. 2; pp. 345 - 352
Main Authors BALOG, A, GEIB, SJ, CURRAN, DP
Format Journal Article
LanguageEnglish
Published WASHINGTON Amer Chemical Soc 27.01.1995
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
MECHANISM
ZIZAANE SESQUITERPENES
ION
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Summary:The effects of nucleophilic additives, Lewis and Bronsted acids, and solvents on BF3.Et(2)O-promoted cationic pi-cyclizations of alkynyl- and alkenylcyclopentane-1,3-diones are reported. The rates and selectivities of alkynyl dione cyclizations were significantly effected by the addition of external nucleophiles or water, and the regioselectivity of cyclization was effected by the choice of reaction solvent. Cyclizations of alkenyl diones, which fail under standard non-nucleophilic conditions, were found to be successful in the presence of added nucleophiles or with Lewis acids other than BF3.Et(2)O. The usefulness of these cationic pi-cyclizations for producing bicyclic ring systems of various functionality was also explored.
ISSN:0022-3263
DOI:10.1021/jo00107a012