Rhodium-Catalyzed Regio-, Diastereo-, and Enantioselective Intermolecular [4+2] Carbocyclization of 4-Alkynals with Electron-Deficient Alkenes
作者:Ken Tanaka、Yuji Hagiwara、Masao Hirano
DOI:10.1002/ejoc.200600383
日期:2006.8
We established that a cationic rhodium(I)/dppf or dppb complexcatalyzes a regio- and diastereoselective intermolecular [4+2] carbocyclization of 5-trimethylsilyl-4-pentynals with electron-deficient alkenes leading to cyclohexanones. We also established that a cationic rhodium(I)/(R,R)-Walphos complexcatalyzes a regio- and enantioselective intermolecular [4+2] carbocyclization of 5-substituted 4-pentynals
Chemoselective Biohydrogenation of Alkenes in the Presence of Alkynes for the Homologation of 2‐Alkynals/3‐Alkyn‐2‐ones into 4‐Alkynals/Alkynols
作者:Danilo Colombo、Elisabetta Brenna、Francesco G. Gatti、Maria Chiara Ghezzi、Daniela Monti、Fabio Parmeggiani、Francesca Tentori
DOI:10.1002/adsc.201900177
日期:——
activated alkene bonds by ene‐reductases (ERs) is completely chemoselective, because of the mechanism of the reaction. Thus, we investigated the use of ERs belonging to the Old Yellow Enzyme family for the reduction of α,β‐unsaturated aldehydes with a conjugated C≡C triple bond at the γ position. This reaction was exploited as the key step for the development of an effective homologation route to convert
Enantioselective Synthesis of Cyclopentenones via Rhodium-Catalyzed Kinetic Resolution and Desymmetrization of 4-Alkynals
作者:Ken Tanaka、Gregory C. Fu
DOI:10.1021/ja0266161
日期:2002.9.1
We have developed two new catalytic processes that provide efficient access to interesting chiral building blocks, cyclopentenones that bear tertiary and quaternary stereocenters, in high enantiomeric excess and very good yield. Structures such as these have potential utility in the synthesis of prostaglandins, pentenomycins, and related compounds.