The first primary aminocatalytic direct cross-aldol reaction of acetaldehyde is presented. Among the various vicinal diamines screened, the L-tert-leucine derivative 1c in conjunction with (H4SiW12O40)0.25 was identified as the optimal catalyst; good catalytic activity (up to 99 % yield in 4 h), and high enantioselectivities (up to 92 % ee) were achieved for a range of donors, including aromatic aldehydes
metal-free total syntheses of antitumor and antiviral agents with the tryptanthrin architecture, that is, phaitanthrin B and cephalanthrin A, along with the biologically active indolidine alkaloids chimonamidine and donaxaridine as well as the formal synthesis of CPC-1. The highly enantioselective outcome of this catalytic crossed aldol reaction was evaluated by calculating the Gibbs free energies of the possible
Asymmetric Aldol Reaction of Acetaldehyde and Isatin Derivatives for the Total Syntheses of <i>ent</i>-Convolutamydine E and CPC-1 and a Half Fragment of Madindoline A and B
作者:Takahiko Itoh、Hayato Ishikawa、Yujiro Hayashi
DOI:10.1021/ol901432a
日期:2009.9.3
The asymmetric aldol reaction of isatin derivatives and acetaldehyde has been developed using 4-hydroxydiarylprolinol as a catalyst, affording the aldol products with high enantioselectivity, these products being key intermediates in the synthesis of 3-hydroxyindole alkaloids. Short syntheses of ent-convolutamydine E and CPC-1 and a half fragment of madindoline A and B have been accomplished.
Primary amine catalyzed aldol reaction of isatins and acetaldehyde
作者:Qunsheng Guo、John Cong-Gui Zhao
DOI:10.1016/j.tetlet.2012.01.108
日期:2012.4
alkaloid-derived chiral primary amines were applied as the catalyst for the cross aldol reaction of isatins with acetaldehyde. With the quinine-derived amine catalyst 3, the desired aldol products were obtained in high yields and good enantioselectivities (up to 93% ee) under the optimized conditions. Although other enolizable aldehydes and ketones may also be applied in this reaction, the ee values obtained