Combined transition-metal- and organocatalysis: an atom economic C3 homologation of alkenes to carbonyl and carboxylic compounds.
A combination of regioselective room-temperature/ambient-pressure hydroformylation (transition-metal catalysis) and decarboxylative Knoevenagel reactions (organocatalysis) allowed for the development of an efficient, one-pot C3 homologation of terminal alkenes to (E)-alpha,beta-unsaturated acids and esters, (E)-beta,gamma-unsaturated acids, (E)-alpha-cyano acrylic acids, and alpha,beta-unsaturated nitriles. All reactions proceed under mild conditions, tolerate a variety of functional groups, and furnish unsaturated carbonyl compounds in good yields and with excellent regio- and stereocontrol. Further, an iterative C2 homologation of (E)-alpha,beta-unsaturated carboxylic acids is possible through a combination of decarboxylative hydroformylation employing a supramolecular catalyst followed by decarboxylative Knoevenagel condensation with an organocatalyst.
Institut für Organische Chemie und Biochemie, Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany.
Susanne T
ST
Kemme
Tomás
T
Smejkal
Bernhard
B
Breit