ISSN:
0170-2041
Keywords:
Phase-transfer catalysis
;
Crown ethers
;
Michael additions
;
c-Alkylations
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Applications of Phase-Transfer Catalysis, 55. - New Experiments towards Enantioselective Phase-Transfer Catalysis with Optically Active Crown EthersOptically active crown ethers 1a-1o,2, 3a, b, 4a, b, 5a-5d, 6a, b and the acyclic analogue 7 were used for three Michael-type additions, benzoin condensation, a C-alkylation, a base-catalyzed autoxidation and a hypochlorite epoxidation. Important observations include a possible reversal of product stereochemistry when changing potassium for sodium ions and when increasing the number of side groups at the crown. Crowns with nonequivalent upper and lower faces are not useful. Additional stereogenic centers in the side chains and OH groups are not advantageous - at least in the studied cases.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199219920149
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