Search results for "Aldimine"

Catalytic Enantioselective Aza-Reformatsky Reaction with Cyclic Imines

2016

A catalytic highly enantioselective aza-Reformatsky reaction with cyclic aldimines and ketimines for the synthesis of chiral b-amino esters with good yields and excellent enantioselectivities is reported.Areadily available diaryl prolinol is used as a chiral ligand, ZnMe2 as a zinc source and ethyl iodoacetate as reagent in the presence of air atmosphere. The reaction with cyclic ketimines generates a quaternary stereocenter with excellent levels of enantioselectivity. Furthermore, five-membered N-sulfonyl ketimines were used as electrophiles with good enantiomeric excesses, under the optimized reaction conditions. Moreover, several chemical transformations were performed with the chiral b-…

Enantioselective copper-aminopyridine-catalyzed aza-Henry reaction with chelating N-(2-pyridyl)sulfonyl imines

2012

This article describes a copper-catalyzed aza-Henry reaction. Copper complexes of camphor-derived aminopyridines catalyze the addition of nitromethane to N-(2-pyridyl)sulfonyl aldimines to give the corresponding β-nitrosulfonamides with good yields and variable enantiomeric excesses (up to 83%). An example of transformation of these compounds into N-(2-pyridyl)sulfonyl-α-amino acids and deprotection of the sulfonamide with Mg–MeOH is provided. Chirality 24:441–450, 2012. © 2012 Wiley Periodicals, Inc.

Reactions of α-diimino ligands with the chloro-bridged dimer [RhCl(COD)]2(COD=1,5-cyclooctadiene)

1988

Abstract The reactions of α-diimino ligands N - N ′ [ N - N ′= 2,2′-bipyridine (bipy), C 5 H 4 N2CHNR (R= C 6 H 4 OMe- p , PyCa), RNCHCHNR (R=C 6 H 4 - OMe- p , DAB)] with [RhCl(COD)] 2 give rise to stoichiometry, solvent, ligand, and temperature dependent equilibria. In general, the 1/1 ligand/dimer reaction yields the ionic product [Rh(COD)( N - N ′)] [RhCl 2 (COD)], at room temperature. For N - N ′=DAB, the ionic form is in equilibrium with the binuclear compound [{RhCl(COD)} (μ-DAB){RhCl(COD)}] (containing a σ σ,'- N , N ′ bridging α-diimine), which becomes the predominant species at low temperatures. In [Rh(COD)( N - N ′)] [RhCl 2 (COD)], a fast exchange of the Rh(COD) unit betwe…

Enantioselective addition of terminal alkynes to N-(diphenylphosphinoyl)imines catalyzed by Zn–BINOL complexes

2012

Abstract Chiral nonracemic N-(diphenylphosphinoyl)-protected propargylic amines have been prepared by addition of terminal alkynes to N-(diphenylphosphinoyl)aldimines in the presence of dimethylzinc and 3,3′-dibromo-BINOL as catalyst. The reaction works with a variety of aromatic and heteroaromatic aldimines and with different alkynes, providing the expected products in generally good yields and enantiomeric excesses (up to 96%).

ChemInform Abstract: Stereoselective Synthesis of 2-Substituted Pyrrolidines.

2000

Using O -pivaloyl protected D-galactopyranosylamine and D-arabinopyranosylamine, ( S ) or ( R ) configured α-substituted homoallylamines are synthesized with high diastereoselectivity by reaction of the corresponding aldimines with allyltributylstannane. Electrophile-induced endo -trig-cyclization of these N -glycosylhomoallylamines gave the 2-substituted pyrrolidines of high diastereomeric purity.

Synthesis, characterization of diorganotin(IV) complexes of N-(2-hydroxyarylidene)aminoacetic acid and antitumour screening in vivo in ehrlich ascite…

2001

Some new diorganotin(IV) complexes have been prepared by reacting potassium N-(2-hydroxyarylidene)aminoacetate with R2SnCl2(R = Me,nBu,Ph). The complexes have been characterized by 1H,13C,119Sn NMR, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analysis. In the solid state, the complexes possess penta- and hexa-coordinated tin centres. The hexa-coordinated tin complexes were found to dissociate in solution, giving rise to penta-coordinated species as revealed by 119Sn NMR spectroscopy. Antitumour screening in vivo of the complexes L4snPh2,L4SnPh2· Ph3SnCl and L4SntBU2·t Bu2SnCl2 (L4 = N-(2-hydroxyacetophenone)aminoacetate) is also reported. Copyright © 2001 …

Stereo and regioselectivity in the phenylation of cationic allylpalladium(II) α-diimine complexes by tetraphenylborate anion

1993

The reaction of the cationic complex [Pd(4-methoxy-1,3-η3-cyclohexenyl)(py-2-CHNC6H4OMe-4)]+ (1) with BPh4− in the presence of fumaronitrile yields trans-3-methoxy-6-phenylcyclohexene (2a) and trans-4-methoxy-3-phenylcyclohexene (2b), in ca. 1 : 1 molar ratio. The trans stereochemistry of these products implies that the phenylation of the allyl ligand involves prior transfer of a phenyl group from BPh4− to the metal, followed by reductive coupling of the organic moieties. In the reactions of [Pd(η3-1,1-R1,R2-C3H3)(NN′)]+ (3) [NN′ 4-MeOH4C6NCHCHNC6H4OMe-4; py-2-CHNR (R  C6H4OMe-4, Me, or CMe3), 2,2′-bipyridine (bipy); R1  H, R2  Ph, Me; R1  R2  Me; with BPh4− in the presence of …

Stereoselective Synthesis of 2-Substituted Pyrrolidines

2000

Using O-pivaloyl protected D-galactopyranosylamine and D-arabinopyranosylamine, (S) or (R) configured α-substituted homoallylamines are synthesized with high diastereoselectivity by reaction of the corresponding aldimines with allyltributylstannane. Electrophile-induced endo-trig-cyclization of these N-glycosylhomoallylamines gave the 2-substituted pyrrolidines of high diastereomeric purity.

Synthesis of Highly Substituted Unsymmetrical 1,2-Diamines, 1,2-Diimines, Imidazolium Salts and Imidazolylidenes by Aldimine Cross-Coupling

2007

α-Aminonitriles derived from aromatic aldehydes and primary amines can be deprotonated quantitatively without the use of protecting groups. The 1,2-addition of the resulting stabilized α-aminocarbanions to imines yields α-aminoimines and the tautomeric enediamines. These unstable compounds can directly be oxidized to 1,2-diimines or reduced to 1,2-diamines in a one-pot reaction. 1,2-Diamines can be obtained in high diastereoselectivity by reduction of the 1,2-diimines. In this case, the relative configuration of the products can be chosen depending on the reduction conditions. Cyclization of the unsymmetrical diimines with halomethyl ethers or esters leads to 1,3,4,5-tetrasubstituted imidaz…

ChemInform Abstract: Highly Enantioselective Zinc/Binol-Catalyzed Alkynylation of N-Sulfonyl Aldimines.

2008