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Topics in Current Chemistry (2020) 378:1
coworkers disclosed an example of reported Michael addition of ketones to alkylidene and allylidene malonates through the use of dual Lewis acid enamine catalysis (Scheme 21a) [123].
Among all the Lewis acids screened, Zn(SbF 6 ) 2 was found to be the most effective catalyst, and THF was shown to be the best solvent for the optimized reaction
conditions. Both five- and six-membered cyclic ketones, including ketones containing heteroatoms, were found to be reactive. Alkylidene malonates and allylidene
malonates bearing both electron-withdrawing and electron-donating groups were
also suitable substrates. Meggers and Kang have simultaneously disclosed the
A
B
Scheme 21 Asymmetric Michael addition of ketones to alkylidene malonates (a), and a rhodium(III)/
amine synergistically catalyzed enantioselective alkylation of aldehydes with α,β-unsaturated 2-acyl imidazoles (b)
Reprinted from the journal
55
Topics in Current Chemistry (2020) 378:1
coworkers disclosed an example of reported Michael addition of ketones to alkylidene and allylidene malonates through the use of dual Lewis acid enamine catalysis (Scheme 21a) [123].
Among all the Lewis acids screened, Zn(SbF 6 ) 2 was found to be the most effective catalyst, and THF was shown to be the best solvent for the optimized reaction
conditions. Both five- and six-membered cyclic ketones, including ketones containing heteroatoms, were found to be reactive. Alkylidene malonates and allylidene
malonates bearing both electron-withdrawing and electron-donating groups were
also suitable substrates. Meggers and Kang have simultaneously disclosed the
A
B
Scheme 21 Asymmetric Michael addition of ketones to alkylidene malonates (a), and a rhodium(III)/
amine synergistically catalyzed enantioselective alkylation of aldehydes with α,β-unsaturated 2-acyl imidazoles (b)
Reprinted from the journal
55