نتایج جستجو برای: mannich reaction

تعداد نتایج: 412927  

Journal: :Chemical communications 2013
Andrej Ďuriš David M Barber Hitesh J Sanganee Darren J Dixon

An efficient one-pot nitro-Mannich/hydroamination cascade reaction for the synthesis of substituted pyrrolidines bearing three stereocentres is reported. Proceeding under the control of a combination of base and gold(I) catalysts, the cascade reaction affords the pyrrolidine products in high yields with good to excellent diastereoselectivities.

Journal: :Organic & biomolecular chemistry 2012
Gert Callebaut Sven Mangelinckx Loránd Kiss Reijo Sillanpää Ferenc Fülöp Norbert De Kimpe

The efficient asymmetric synthesis of new chiral γ-chloro-α,β-diamino acid derivatives via highly diastereoselective Mannich-type reactions of N-(diphenylmethylene) glycine esters across a chiral α-chloro-N-p-toluenesulfinylimine was developed. The influence of the base, LDA or LiHMDS, used for the formation of the glycine enolates, was of great importance for the anti-/syn-diastereoselectivity...

Journal: :Chemical communications 2008
Domingo García-Cuadrado Sofia Barluenga Nicolas Winssinger

A concise sequence utilizing a Petasis three component reaction followed by a tandem aza-Cope-Mannich cyclization afforded novel polycyclic heterocycles in good yield; alternative iminium cyclization based on a Pictet-Spengler reaction or aminal formation led to divergent pathways affording skeletal diversity.

Journal: :Organic letters 2006
Amal Ting Sha Lou Scott E Schaus

[reaction: see text] The cinchona alkaloids catalyze direct asymmetric Mannich reactions of cyclic 1,3-dicarbonyl compounds with acyl imines to afford alpha-quaternary carbon-bearing reaction products in yields of up to 98%, a diastereomeric excess of 90% or greater, and enantioselectivities up to 99% ee. A model is proposed that accounts for both the observed diastereoselectivities and the ena...

Journal: :Organic letters 2007
Lifeng Wan Marcus A Tius

The allene ether version of the Nazarov cyclization was used to construct the cyclopentane dione portion of madindolines A and B. The racemic cyclopentane dione from the Nazarov cyclization was converted to an enol ether that was combined with the chiral, nonracemic hydroxyfuroindoline in a Mannich reaction. Deprotection and oxidation led to (+)-madindoline A and (+)-madindoline B. [reaction: s...

Journal: :Organic letters 2002
Shin-ichi Watanabe Armando Córdova Fujie Tanaka Carlos F Barbas

[reaction: see text] One-pot asymmetric Mannich-hydrocyanation reactions are described. Reaction of unmodified aldehydes with N-PMP-protected alpha-imino ethyl glyoxylate in the presence of catalytic amounts of L-proline followed by the addition of Et(2)AlCN provided highly enantiomerically pure beta-cyanohydroxymethyl alpha-amino acid derivatives possessing three contiguous stereogenic centers...

Journal: :Organic & biomolecular chemistry 2014
Norio Shibata Takayuki Nishimine Naoyuki Shibata Etsuko Tokunaga Kosuke Kawada Takumi Kagawa José Luis Aceña Alexander E Sorochinsky Vadim A Soloshonok

Inorganic as well as organic base catalysis was found to be effective for diastereoselective Mannich additions of malonic acid derivatives to (SS)-N-(tert-butanesulfinyl)-3,3,3-trifluoroacetaldimine. In the presence of catalytic amounts of inorganic bases, n-BuLi or DMAP, the reaction gives the corresponding (R,SS)-β-aminomalonates in good yield and with diastereoselectivity up to 9/1 dr. In co...

Journal: :Journal of the American Chemical Society 2006

Journal: :Journal of Synthetic Organic Chemistry, Japan 2000

Journal: :Asian Journal of Organic Chemistry 2022

The mechanistic analysis of catalyst-controlled regiodivergent aza-Morita-Baylis-Hillman reactions vinylcyclopentenone is described. DABCO-catalyzed reaction gives the α-adduct exclusively (red reaction) and DMAP-catalyzed produces γ-adduct selectively (blue reaction). revealed that rate-determining step (RDS) α-selective Mannich-type C−C bond formation step, whereas RDS γ-selective seems to be...

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