1043892-65-4Relevant academic research and scientific papers
Guanidine-catalyzed asymmetric synthesis of 2,2-disubstituted chromane skeletons by intramolecular oxa-Michael addition
Saito, Noriko,Ryoda, Akemi,Nakanishi, Waka,Kumamoto, Takuya,Ishikawa, Tsutomu
supporting information; experimental part, p. 2759 - 2766 (2009/04/07)
The guanidine-catalyzed 6-exo-trig-type intramolecular asymmetric oxa-Michael addition of α,β-unsaturated esters with a 2-hydroxyaryl moiety at the C-5 carbon has been examined for the construction of chromane skeletons with a quaternary carbon chiral center. The bulkiness of the alkyl group and the E/Z geometry of the α,β-unsaturated ester function played important roles in the asymmetric induction and (4S,5S)-2-[(R)-1- hydroxymethyl-2-phenylethylimino]-1,3-dimethylimidazolidine (or its enantiomer) carrying aryl pendants at the 4- and 5-positions was found to be the most effective catalyst among 18 chiral guanidines examined. In this way, the Z isomer of the less bulky methyl ester was subjected to the cyclization reaction, affording chiral chromane in up to 83% yield with 76% ee. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
