γ-Oxygenation of α,β-Unsaturated Esters by Vinylogous O-Nitroso Mukaiyama Aldol Reaction
摘要:
A practical procedure has been developed for gamma-oxygenation of alpha,beta-unsaturated esters by a vinylogous O-nitroso Mukaiyama aldol reaction followed by a one-pot N-O bond heterolysis of the in situ generated gamma-aminoxy-alpha,beta-unsaturated esters.
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
Lewis Base Activation of Lewis Acids. Vinylogous Aldol Reactions
作者:Scott E. Denmark、Gregory L. Beutner
DOI:10.1021/ja035448p
日期:2003.7.1
A highly regioselective vinylogous aldol reaction catalyzed by SiCl4 and a chiral phosphoramide (R,R)-5, providing delta-hydroxy enones for a variety of aldehyde and dienol ether structures, has been developed. Low catalyst loadings (1 mol %) can be employed, giving the products in good yields, excellent enantioselectivities, and in some cases excellent anti diastereoselectivities. Both simple ester-derived
An enantioselective synthesis of the polyene macrolideRK-397 is described. The use of the same eight-carbon building block twice for the construction of the polyol chain allowed for a highly convergent synthesis. The synthesis highlights stereoselective vinylogous aldol addition using a chiral bisphosphoramide as well as a sequential palladium-catalyzed cross-coupling reaction for the preparation
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
Lewis Acid-Promoted Conjugate Addition of Dienol Silyl Ethers to Nitroalkenes: Synthesis of 3-Substituted Azepanes
作者:Scott E. Denmark、Min Xie
DOI:10.1021/jo071126i
日期:2007.8.31
A novel γ-selective conjugateaddition of 1-silyl-substituted dienol ethers to nitroalkenes activated by Lewis acids has been developed. The resulting α,β-unsaturated acylsilanes undergo photoinduced protodesilylation to afford the corresponding enals, which can be conveniently transformed into azepanes under appropriate reductive conditions.