Chiral Organotin Research Articles

A highly enantioselective approach towards optically active γ-amino alcohols by tin-catalyzed kinetic resolution of 1,3-amino alcohols.

A highly enantioselective kinetic resolution of racemic 1,3-amino alcohols via O-Acylation was achieved using a chiral organotin as the catalyst. Alkyl- and aryl-substituted 1,3-amino alcohols were resolved with excellent efficiencies to afford the recovered 1,3-amino alcohols and acylative products with high enantioselectivities, with s factors up to >600. Notably, the chiral organotin catalyst was more selective for anti-1,3-amino alcohols than for syn-isomers. A Gram-scale reaction with loading using 2 mol% catalysts demonstrated the utility of this protocol.

Chiral‐Organotin‐Catalyzed Kinetic Resolution of Vicinal Amino Alcohols

AbstractA highly efficient kinetic resolution of racemic amino alcohols has been achieved for the first time with a chiral tin catalyst. A chiral organotin compound with 3,4,5‐trifluorophenyl groups at the 3,3′‐positions of the binaphthyl framework enabled this transformation with excellent yield and high enantioselectivity. The process tolerates aryl‐ and alkyl‐substituted amino alcohols and a variety of other substrates, affording the corresponding products in high enantioselectivity and with s factors up to >500.

Chiral-Organotin-Catalyzed Kinetic Resolution of Vicinal Amino Alcohols.

A highly efficient kinetic resolution of racemic amino alcohols has been achieved for the first time with a chiral tin catalyst. A chiral organotin compound with 3,4,5-trifluorophenyl groups at the 3,3'-positions of the binaphthyl framework enabled this transformation with excellent yield and high enantioselectivity. The process tolerates aryl- and alkyl-substituted amino alcohols and a variety of other substrates, affording the corresponding products in high enantioselectivity and with s factors up to >500.

Luminescent Silk Fibroin with Organotin Compounds from Amino Acid Schiff Bases – Microwave‐Assisted Synthesis, Chemo‐Optical Characterization, Cytotoxicity, and Confocal Microscopy

In this work, we report the microwave‐assisted synthesis of six new pentacoordinate and chiral organotin compounds (1–6) derived from amino acid based Schiff bases. The syntheses were achieved through multicomponent reactions (MCRs) of l‐amino acids (tryptophan, tyrosine, and phenylalanine), 2‐hydroxy‐1‐naphthaldehyde, and the corresponding diorganotin oxide (R2SnO, R = nBu or Ph). These compounds were characterized by NMR spectroscopy (1H, 13C, and 119Sn), HRMS, UV/Vis spectroscopy, and fluorescence spectroscopy. All of the compounds in solution exhibited fluorescence with quantum yields (Φ) in the range 0.08 to 0.21. The cytotoxicities of 1–6 at 0.1 µg mL–1 were investigated, and they are practically harmless to melanoma B16F10 cells. The fluorescent staining ability of the organotin compounds toward silk fibroin was investigated by the immersion method and analyzed by confocal microscopy, which showed the efficient and uniform integration of the luminescent compounds. DFT calculations of the interactions of a truncated organotin–fibroin complex are also reported.

Chiral Organotin Hydride Catalyzed Enantioselective Radical Cyclization of Aldehydes

Chiral Organotin Hydride Catalyzed Enantioselective Radical Cyclization of Aldehydes

ChemInform Abstract: Development of Asymmetric Reactions Catalyzed by Chiral Organotin—Alkoxide Reagents

AbstractReview: 79 refs.

Pt-based chiral organotin modified heterogeneous catalysts for the enantioselective hydrogenation of 3,4-hexanedione

In this paper we have studied the liquid-phase enantioselective hydrogenation of 3,4-hexanedione using Pt-based catalysts, modified with chiral organotin compounds derived from the (−)-menthyl group: (−)-Pt-MenSnBu3 and (−)-Men3Sn-Sn-(−)-Men3. The organotin chiral modifiers were carefully synthesized and characterized in order to obtain optically pure compounds.The catalysts were prepared through a controlled surface reaction between the supported transition metal and the organometallic compound, using techniques derived from Surface Organometallic Chemistry on Metals (SOMC/M). The organobimetallic catalytic systems were found to be active and enantioselective in the hydrogenation of 3,4-hexanedione, yielding an enantiomeric excess of 25–27% for 4-hydroxy-3-hexanone.

De novo design of chiral organotin cancer drug candidates: Validation of enantiopreferential binding to molecular target DNA and 5′-GMP by UV–visible, fluorescence, 1H and 31P NMR

N,N-bis[(R-/S-)-1-benzyl-2-ethoxyethane] tin (IV) complexes were synthesized by applying de novo design strategy by the condensation reaction of (R-/S-)2-amino-2-phenylethanol and dibromoethane in presence of dimethyltin dichloride and thoroughly characterized by elemental analysis, conductivity measurements, IR, ESI-MS, 1H, 13C and 119Sn, multinuclear NMR spectroscopy and XRD study. Enantioselective and specific binding profile of R-enantiomer 1 in comparison to S-enantiomer 2 with ultimate molecular target CT-DNA was validated by UV–visible, fluorescence, circular dichroism, 1H and 31P NMR techniques. This was further corroborated well by interaction of 1 and 2 with 5′-GMP.

Chiral organotin (IV) carboxylates complexes: Syntheses, characterization, and crystal structures with chiral (S)-(+)-6-methoxy- α-methyl-2-naphthaleneaceto acid ligand

Eight new organotin (IV) carboxylates, (R 3Sn) 4(nap) 4 (R = Me 1, n-Bu 2), [(R 3Sn) (nap)] n (R = Ph 3, PhCH 2 4), (R 2Sn) (nap) 2 (R = n-Bu 5, Ph 6, PhCH 2 7) and {[R 2Sn(nap)] 2O} 2 (R = Me 8) (nap = (S)-(+)-6-methoxy- α-methyl-2-naphthaleneaceto anion) have been synthesized. All of the complexes have been characterized by elemental analysis, FT–IR, NMR ( 1H, 13C and 119Sn) spectra. Among these complexes, complexes 1, 3, 5 and 8 were also characterized by X-ray crystallography diffraction analysis, and the data of X-ray crystallography diffraction indicated that complexes 1, 3 and 5 are new chiral organotin (IV) carboxylates complexes. The structural analyses show that complex 1 has a tetranuclear Sn 4O 8 macrocycle structure, complex 3 has a 1D spring-like chiral helical chain with a columnar channel, complex 5 possesses a dimer structure, and complex 8 has a supramolecular chainlike ladder structure through weak intermolecular non-covalent O …O interactions.

ChemInform Abstract: Chemo- and Stereoselective Monobenzoylation of 1,2-Diols Catalyzed by Organotin Compounds.

A new facile method for monoacylation of diols has been developed. A variety of cyclic and acyclic diols, in particular 1,2-diols, were selectively monobenzoylated in good yields by the reaction with benzoyl chloride in the presence of a catalytic amount of dimethyltin dichloride and inorganic bases such as potassium carbonate. Furthermore, the method was successfully applied to a kinetic resolution of racemic 1-phenyl-1,2-ethanediol using a chiral organotin catalyst. The ee was dependent on the kind of base, water as an additive, and the reaction temperature.

Towards a rational design of enantioselective heterogeneous catalysts: Modeling of chiral organotin precursors

In this work, the modeling of organotin compounds of general formula Men-Sn-R 3 (Men = menthyl, R = alkyl or alkoxyalkyl) is carried out. These compounds can be employed as precursors for obtaining enantioselective heterogeneous catalysts, prepared by means of Surface Organometallic Chemistry on Metals techniques. Both Molecular Mechanics and Molecular Dynamics, as well as Density Functional Theory (DFT), were used to give an insight into the relative stability of the Sn–C bonds of several different organotin compounds. The calculations carried out on the molecules Men-Sn-(iso-Bu) 3 and Men-Sn-((1-OCH 3)-Et) 3 showed that if these molecules are used as precursor compounds to prepare heterogeneous organobimetallic catalysts, the probability of losing the menthyl group in a dissociation process is lower, leading to a better performance of the resulting catalysts, in terms of enantiomeric excess.

Herbert Schumann (1935–2010)

Herbert Schumann (1935–2010)

Chiral organotin complexes stabilized by C,N-chelating oxazolinyl-o-carboranes

Abstract A series of chiral organotin halides containing 2-(4-R)-oxazolinyl-o-carboranes (R = i-propyl 1, t-butyl 2; CabOxa) was prepared from o-carborane with a chiral oxazoline auxiliary. X-ray structural analysis of the representative chiral organotin halide, [2-(4-i-propyl)-oxazolinyl-o-carboranyl]SnMe2Br (4), revealed the formation of a stable penta-coordinated tin center due to a N → Sn interaction. Similar O → Sn assisted intramolecular penta-coordinated tin complexes (9 and 10) were prepared from methoxy-o-carborane ligands, MeOCH(Z)-o-carborane (Z = H 7, Ph 8; CabOMe), respectively, and a rigid o-carboranyl backbone provided the basic skeleton for the facile formation of organotin complexes.

Selective Molecular Transformation of 1,2‐Diols Based on Molecular Recognition

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

１，２‐ジオール分子認識に基づく選択的分子変換反応

On the bases of the concept that a coordination of 1, 2-diols 1 with an appropriate metal ion (Mn+) might form an activated five-membered intermediate in which the OH group is much activated than those of non-activated 1, we examined a monobenzoylation of 1 by benzoyl chloride using tin and copper ions as Mn+. As the results, the monobenzoylation of 1 was achieved with high selectivity even in the presence of monools. The monobenzoylation reactions were then applied to kinetic resolution of dl-1 and asymmetric desymmetrization of meso-1 using a chiral organotin or BOX (bisoxazoline) -CuCl2 as a catalyst. In particular, the asymmetric outcome using (R, R) -Ph-BOX-CuCl2 catalyst was promising and attractive. That is, the kinetic resolution of dl-1 (with up to >99.9% ee for monobenzoylation of hydrobenzoin), its application to a synthesis of D-inositol-1-phosphate (100% ee), the asymmetric desymmetrization of meso-1 (with up to 94% ee for monobenzoylation of meso-1, 2-hydrobenzoin and 93% ee for monocarbamoylation of meso-1, 2-cyclooctanediol), and the asymmetric desymmetrization of meso-1, 3-diols (with up to 55% ee for the monobenzoylation of ethyl 2-ethyl-2-hydroxymethyl-3-hydroxypropanoate) were achieved. Also, the method was applied to electrochemical oxidation of 1 and its asymmetric version (38% ee for the asymmetric desymmetrization of meso-hydrobenzoin and 72% ee for the kinetic resolution of dl-hydrobenzoin).

Synthesis, characterization and nonlinear optical properties in a series of new chiral organotin(IV) Schiff base complexes

Four new chiral organotin derivatives are reported with their crystal structure. They were synthesized by reaction of diphenyltin oxide and four different ligands obtained from the Schiff base condensation of 4-(diethylamino)salicylaldehyde and (1 R,2 S)-(+)-norephedrine, ( R)-(−)-phenylglycinol, ( R)-(−)-1-amino-2-propanol and (1 S,2 R)-2-amino-1,2-diphenylethanol. Their nonlinear optical properties were investigated experimentally in solid state and with the electric field induced second harmonic (EFISH) technique. In particular, the compound obtained with ( R)-(−)-phenylglycinol exhibits an efficiency 11 times that of urea in second harmonic generation at 1.907 μm. The properties are discussed in relation with computational studies conducted within the framework of the DFT theory.

Chiral self-assembly of methyltin(IV)-naproxenates: Combining dative Sn–O bonds, secondary Sn⋯O interactions and C–H⋯O hydrogen bonding to make an inter-helical meander-shaped network and a cross-linked Z-shaped ribbon

Three new chiral organotin(IV) carboxylates, Me 2Sn(nap) 2 ( 1), {[Me 2Sn(nap)] 2O} 2 ( 2) and Me 3Sn(nap) ( 3) (nap = ( S)-(+)-6-methoxy-α-methyl-2-naphthaleneaceto anion) have been synthesized. All of them have been characterized by elemental analysis, multinuclear ( 1H, 13C and 119Sn) NMR and IR spectroscopy. The crystal structures of 1 and 2 have been determined by X-ray diffraction analysis. The bicapped tetrahedral molecules of 1 are linked by C–H⋯O hydrogen bonds into homochiral helices, which are also interconnected by C–H⋯O interactions to form an inter-helical meander-shaped network. The molecule of 2 is a parallel double helix incorporating four chiral tin centers in a Sn 4O 10C 4 ladder type molecular skeleton. The C–H⋯O interactions translate the molecular chirality of 2 throughout the crystal via formation of infinite ribbons. These ribbons in their turn are further cross-linked by C–H⋯O hydrogen bonds. The structural characterization of the complexes 1– 3 in solution has been performed by routine multinuclear 1H, 13C and 119Sn NMR as well as specialized multidimensional ( 1H– 119Sn-gHMQC and 1H-DOSY) experiments. The relevant 2 J 1 H – 119 Sn and 1 J 13 C – 119 Sn coupling constants have been extracted and related to molecular geometries on the basis of the literature data. The measurement of the translational diffusion constants using diffusion ordered spectroscopy allowed the estimation of the spherical hydrodynamic radii of the newly prepared structures.

Organotin compounds: from kinetics to stereochemistry and antitumour activities

AbstractAn overview is given of the research performed by the authors at the Université Libre de Bruxelles and Vrije Universiteit Brussel, including the kinetics, stereochemistry and mechanism of SE2 reactions at a saturated carbon atom, the synthesis of chiral organotin compounds and their configurational and optical stability, the fluxionality of trigonal bipyramidal metal atoms and the stereochemistry of SN2 reactions at tetrahedrally substituted P, Si, Ge, Sn atoms, the cytotoxicity of many series of organotin compounds and the structure and reactivity of organotin salicylaldoximate clusters. Copyright © 2005 John Wiley & Sons, Ltd.

Asymmetric Radical Reduction with Planar Chiral Organotin Hydrides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Asymmetric Radical Reduction with Planar Chiral Organotin Hydrides

Asymmetric Radical Reduction with Planar Chiral Organotin Hydrides