Two simple analogues (3 and 4) of a bracken ultimate carcinogen 2 have been synthesized. These compounds, 3 and 4, have been shown to possess the DNAcleavingactivities comparable to that of natural ultimate carcinogen 2.
Lewis Base Activation of Lewis Acids: Catalytic, Enantioselective Addition of Silyl Ketene Acetals to Aldehydes
作者:Scott E. Denmark、Gregory L. Beutner、Thomas Wynn、Martin D. Eastgate
DOI:10.1021/ja047339w
日期:2005.3.1
The concept of Lewisbase activation of Lewisacids has been reduced to practice for catalysis of the aldolreaction of silyl ketene acetals and silyl dienol ethers with aldehydes. The weakly acidic species, silicon tetrachloride (SiCl4), can be activated by binding of a strongly Lewis basic chiral phosphoramide, leading to in situ formation of a chiral Lewisacid. This species has proven to be a competent
Disulfonimide-Catalyzed Asymmetric Vinylogous and Bisvinylogous Mukaiyama Aldol Reactions
作者:Lars Ratjen、Pilar García-García、Frank Lay、Michael Edmund Beck、Benjamin List
DOI:10.1002/anie.201005954
日期:2011.1.17
talk about six! A new chiral disulfonimide catalyzed vinylogous Mukaiyamaaldol addition of crotonic acid derived nucleophiles to aldehydes has been developed and the concept of vinylogy was further expanded to double vinylogous, sorbic acid derived nucleophiles. This reaction is an example of a previously unknown ε‐selective bisvinylogous MukaiyamaAldol addition that extends the substrate by six