Sequential Reactions Promoted by Manganese: Completely Stereoselective Synthesis of (E)-α,β-Unsaturated Amides, Ketones, Aldehydes, and Carboxylic Acids
摘要:
A complete E-selective synthesis of a,alpha,beta-unsaturated amides through a sequential reaction of a range of dichloroamides with a variety of aldehydes promoted by Rieke manganese (Mn*) is reported. A mechanism based on a sequential aldol-type reaction and a completely stereoselective beta-elimination is proposed to explain these results. The unsaturated amides obtained are readily and efficiently transformed into alpha,beta-unsaturated ketones, aldehydes, or carboxylic acids without loss of the diastereoisomeric purity of the C-C double bond.
Stereospecific Cyclopropanation of Highly Substituted C−C Double Bonds Promoted by CrCl<sub>2</sub>. Stereoselective Synthesis of Cyclopropanecarboxamides and Cyclopropyl Ketones
作者:José M. Concellón、Humberto Rodríguez-Solla、Carmen Méjica、Elena G. Blanco
DOI:10.1021/ol070896d
日期:2007.8.1
(Z)-alpha,beta-enamides in which the C-C double bond is di-, tri-, or tetrasubstituted. In all cases the process is completely stereospecific and only a single diastereoisomer is obtained. In addition, cyclopropyl ketones were readily prepared by reaction of the cyclopropanecarboxamides (derived from morpholine) obtained with a range of organolithium compounds. A mechanism has been proposed to explain the cyclopropanation
Tetrasubstituted Allene Ethers; Synthesis and Use in Nazarov Reactions
作者:Marcus A. Tius、Bradley K. Tokeshi
DOI:10.1055/s-2004-815994
日期:——
A method for the synthesis of tetrasubstituted allene ethers is described, making use of a reverseBrookrearrangement in the key step. The allene products have been used in the Nazarov cyclization reaction.
Asymmetric Cyclopentannelation. Chiral Auxiliary on the Allene
作者:Paul E. Harrington、Marcus A. Tius
DOI:10.1021/ol0001362
日期:2000.8.1
An enantioselective variant of the synthesis of cross-conjugated cyclopentenones, based on D-glucose-derived chiral auxiliaries, is described. Minor modification of the method makes it applicable to the preparation of both enantiomeric series of products. Both enantiomers of the key intermediate in our roseophilin synthesis have been prepared.
CrCl<sub>2</sub>-Promoted Stereospecific and Stereoselective Alkyl- and Silylcyclopropanation of α,β-Unsaturated Amides
作者:José M. Concellón、Humberto Rodríguez-Solla、Carmen Méjica、Elena G. Blanco、Santiago García-Granda、M. Rosario Díaz
DOI:10.1021/jo800103t
日期:2008.5.1
An efficient chromium-promoted alkyl- or silylcyclopropanation of α,β-unsaturated amides is described. These reactions can be carried out on (E)- or (Z)-α,β-enamides in which the C−C double bond is di-, or trisubstituted. This process takes place with totalstereospecificity and the new stereogenic center is generated with high or total stereoselectivity. Some synthetic applications of the obtained
Cobalt-Catalyzed Reductive Carboxylation of α,β-Unsaturated Compounds with Carbon Dioxide
作者:Chika Hayashi、Takuo Hayashi、Tohru Yamada
DOI:10.1246/bcsj.20150043
日期:2015.6.15
The gaseous carbon dioxide incorporation reaction with α,β-unsaturated compounds was examined in the presence of a catalytic amount of bis(acetylacetonato)cobalt(II) and using diethylzinc as a redu...
在催化量的双(乙酰丙酮)钴 (II) 存在下,并使用二乙基锌作为还原剂,研究了气态二氧化碳与 α,β-不饱和化合物的掺入反应。