نتایج جستجو برای: stereoselectively

تعداد نتایج: 274  

Journal: :The Journal of organic chemistry 2009
Yohan Georges Xavier Ariza Jordi Garcia

(-)-Spicigerolide was stereoselectively synthesized from a protected (S)-lactaldehyde. The synthesis of the polyacetylated framework relied on two Zn-mediated stereoselective additions of alkynes to aldehydes as well as a regiocontrolled [3,3]-sigmatropic rearrangement of an allylic acetate. The pyranone moiety was constructed via ring-closing metathesis.

Journal: :Faraday discussions 2014
Jelena Stojaković Brian S Farris Leonard R MacGillivray

We employ vortex grinding to generate a [2.2]paracyclophane in the organic solid state. The vortex grinding is aided with the addition of a small amount of liquid phase to facilitate topochemical [2 + 2] photodimerizations that generate the cyclophane stereoselectively and in up to quantitative yield. The use of the liquid phase increases the scope of the vortex method.

2008
Jin-Yong Lu Wei-Zheng Shen Hans Preut Hans-Dieter Arndt

The title compound, C(6)H(9)NO(4), was prepared stereoselectively as a precursor for 1-aza-dienes in a study of hetero-Diels-Alder reactions. The configuration of the C=N double bond was found to be Z, corroborating earlier assignments of similar compounds based only on NMR and IR spectroscopic analysis.

Journal: :Chemical communications 2014
Joan Guasch Yolanda Díaz M Isabel Matheu Sergio Castillón

The reaction of dienyl carbamates with PhI(OR)2 in the presence of rhodium catalysts affords vinyl aziridines which are in situ regio- and stereoselectively opened to afford oxyamination products resulting from a selective S(N)2 (Rh2(OAc)4/PhI(OPiv)2) or S(N)2' (Rh2(OPiv)4/PhI(OAc)2) opening. The scope and limitations of this tandem process are described.

1999
Li-Xin Dai Xue-Long Hou Yong-Gui Zhou

Three types of small ring compounds (epoxides, aziridines and cyclopropanes) can be synthesized stereoselectively via ylide route. Among them, the stereochemistry of vinyloxiranes, vinylaziridines, cyclopropylesters, amides and ketones can be tuned by the choice of reaction conditions and ylides with varying heteroatoms and ligands. Optically active epoxides and acetylenylaziridines can be prep...

2012
Melinda Nonn Loránd Kiss Reijo Sillanpää Ferenc Fülöp

A rapid and simple procedure was devised for the synthesis of multifunctionalized cyclic β-amino esters and γ-amino alcohols via the 1,3-dipolar cycloaddition of nitrile oxides to β-aminocyclopentenecarboxylates. The opening of the isoxazoline reductive ring to the corresponding highly functionalized 2-aminocyclopentanecarboxylates occurred stereoselectively with good yields.

Journal: :Organic & biomolecular chemistry 2010
Tomoya Miura Hiroshi Shimizu Tomohiro Igarashi Masahiro Murakami

Vinyl-substituted (Z)-stilbenes are stereoselectively synthesised on treatment of 4-arylbuta-2,3-dien-1-ols with arylboronic acids in the presence of a rhodium(i) catalyst. The reaction proceeds through the regioselective addition of organorhodium(i) species across the aryl-substituted carbon-carbon double bond of the allene moiety and subsequent delta-elimination of Rh(i)-OH.

Journal: :Chemical communications 2014
Giannis S Papaefstathiou Andrew J E Duncan Leonard R MacGillivray

We describe hydrogen-bonded dimers of catechol that act collectively as a single template to direct an intermolecular [2+2] photocycloaddition in the solid state. The directed reactivity involves discrete, six-component hydrogen-bonded assemblies and a photoreaction that occurs stereoselectively and in quantitative yield.

Journal: :Angewandte Chemie 2012
Lukas M Kreis Erick M Carreira

Cascading to alkaloids: an 18-step total synthesis of (-)-dendrobine is based on a reaction cascade with a key amine group. The amine is the initiator of the cascade and provides an efficient method for installing the stereocenters at C11 and C3. The overall transformation occurs stereoselectively only when the conversion is carried out without the isolation of intermediates.

Journal: :Beilstein Journal of Organic Chemistry 2008
Deniz Akalay Gerd Dürner Jan W Bats Michael W Göbel

C(2)-symmetric bisamidines 8 have been tested as chiral Brønsted bases in the Diels-Alder reaction of anthrones and N-substituted maleimides. High yields of cycloadducts and significant asymmetric inductions up to 76% ee are accessible. The proposed mechanism involves proton transfer between anthrone and bisamidine, association of the resulting ions and finally a cycloaddition step stereoselect...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید