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Intramolecular Ene and Related Reactions, 5 3g) . Stereoselective Formation of trans ‐1,2‐Disubstituted Cyclopentanes by Intramolecular Cyclisation of Allylsilane Alkylidene 1,3‐Dioxo Compounds
Author(s) -
Tietze Lutz F.,
Ruther Michael
Publication year - 1990
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19901230631
Subject(s) - chemistry , intramolecular force , moiety , cyclopentanes , knoevenagel condensation , lewis acids and bases , medicinal chemistry , stereoselectivity , intramolecular reaction , stereochemistry , ene reaction , organic chemistry , catalysis
The alkylidene 1,3‐dioxo compounds 4a–d with an allylsilane moiety undergo a fluoride‐, Lewis acid‐ and TMSOTf‐induced intramolecular cyclisation to give almost exclusively the trans ‐1,2‐disubstituted cyclopentanes 5a–d in good to excellent yields. The diastereoselectivity of the reaction was determined as a function of the 1,3‐dioxo moiety and the inductor. The best results were obtained with FeCl 3 /Al 2 O 3 followed by TMSOTf and Me 2 AlCl 1 the highest selectivity was found in the cyclisation of 4b with TMSOTf leading to 5b and 6b in a ratio of 99.8:0.2. FeCl 3 /Al 2 O 3 and TMSOTf have not previously been used for this type of reaction. The alkylidene 1,3‐dioxo compounds 4a–d were synthesised by Knoevenagel condensation of the aldehyde 11 with the malonic acid derivatives 11a–d .