Direct Mannich-Type Reactions Promoted by Frustrated Lewis Acid/Brønsted Base Catalysts.
Direct Mannich-type reactions that afford both α- and β-amino esters by the reaction of a broad range of carbonyl compounds and aldimines are disclosed. The transformation is promoted by a sterically frustrated Lewis acid/Brønsted base pair, which is proposed to operate cooperatively: Within the catalyst complex, an enolate is generated that then reacts with a hydrogen-bond-activated imine. Noncovalent interactions between reactants and the catalyst provide selectivity and new opportunities for future catalyst design.
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts, 02467, USA.
Jessica Z
JZ
Chan
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts, 02467, USA.
Wenzhi
W
Yao
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts, 02467, USA.
Brian T
BT
Hastings
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts, 02467, USA.
Charles K
CK
Lok
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts, 02467, USA. wasa@bc.edu.
Masayuki
M
Wasa
Lewis acids; Mannich-type reactions; acid-base catalysis; boron; frustrated Lewis pairs