Highly enantioselective catalytic Michael reaction of α-substituted malonates using La-linked-BINOL complex in the presence of HFIP (1,1,1,3,3,3-hexafluoroisopropanol)

✍ Scribed by Ryo Takita; Takashi Ohshima; Masakatsu Shibasaki

• Book ID: 104251300
• Publisher: Elsevier Science
• Year: 2002
• Tongue: French
• Weight: 133 KB
• Volume: 43
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(02)00882-1

✦ Synopsis

A catalytic asymmetric Michael reaction of a-substituted malonates with broad generality was developed using the La-linked-BINOL complex. To enhance the reactivity of unreactive a-substituted malonates, we examined the effects of concentration and additives; 1.0 M was the best concentration and HFIP (1,1,1,3,3,3-hexafluoroisopropanol) accelerated the reaction efficiently. Under the optimized conditions, the catalytic asymmetric Michael reaction of a variety of a-substituted malonates proceeded successfully in high yield (up to 93%) and excellent enantiomeric excess (up to 99% ee). The addition of HFIP was also effective for the reaction of nonsubstituted malonates. In this case, 5 mol% of the La-linked-BINOL complex was sufficient for completion of the reaction in approximately 24 h. Moreover, several Michael adducts were readily converted to the bicyclic compounds.