Microwave‐Assisted Rhodium‐Complex‐Catalyzed Cascade Decarbonylation and Asymmetric Pauson–Khand‐Type Cyclizations
作者:Hang Wai Lee、Lai Na Lee、Albert S. C. Chan、Fuk Yee Kwong
DOI:10.1002/ejoc.200800272
日期:2008.7
Microwave-assisted Rh–diphosphane-complex-catalyzed dual catalysis is reported. This cooperative process provides [2+2+1] cycloadducts by sequential decarbonylation of aldehyde or formate and carbonylation of enynes within a short period of time. Various O-, N-, and C-tethered enynes were transformed into the corresponding products in good yields. The first enantioselective version of this microwave-accelerated
Utilization of Aldoses as a Carbonyl Source in Cyclocarbonylation of Enynes
作者:Keiichi Ikeda、Tsumoru Morimoto、Kiyomi Kakiuchi
DOI:10.1021/jo1012288
日期:2010.9.17
The reaction of enynes with acetyl-masked aldoses in the presence of a rhodium(I) catalyst resulted in cyclocarbonylation, thus avoiding the direct use of carbon monoxide, to afford bicyclic cyclopentenones. In rhodium catalysis, aldoses serve as a carbon monoxide equivalent by donating their carbonyl moieties on the acyclic aldehyde form to enynes. A variety of aldoses, including d-glucose, d-mannose
With aldehydes as a CO source under solvent-free conditions, rhodium complex efficiently catalyzed an intramolecular carbonylative alkene-alkyne coupling (Pauson-Khand-type reaction) and various bicyclic enones were obtained in high yield. Experiments under argon flow and a C-13-labeling experiment suggested that almost no free carbon monoxide was generated in this reaction, When noncationic rhodium complex with chiral phosphine was used as a chiral catalyst, the reaction proceeded enantioselectively to give various chiral cyclopentenones in up to 90% ee under solvent-free conditions.