1,5-Stereocontrol in tin(IV) halide promoted reactions of 2-alkoxy-1-(2-tributylstannylethylidene)cyclohexanes with aldehydes

2-Methoxy- and 2-(p-methoxybenzyloxy)-1-(2-tributylstannylethylidene)cyclohexanes 22 and 23 were prepared from 2-methoxy- and 2-(p-methoxybenzyloxy)cyclohexanones 12 and 13. The allylstannane 22 was transmetallated stereoselectively with tin(IV) chloride at −78 °C to generate an allyltin trihalide, which reacted with aldehydes to give (Z)-(3-hydroxyalkylidene)-2-methoxycyclohexanes 24 with excellent 1,5-syn-stereocontrol. Similar reactions with aldehydes were observed for the 2-(p-methoxybenzyloxy) substituted allylstannane 23. The structure of the product 24f prepared from p-nitrobenzaldehyde was confirmed by an X-ray structure determination of its p-nitrobenzoate ester 27.     

1,5-Stereocontrol in reactions of 2,4-disubstituted alk-2-enylstannanes with aldehydes; an approach to the stereoselective synthesis of branched triols

2-(tert-Butyldimethylsilyloxymethyl)-4-(methoxymethoxy)pent-2-enyl(tributyl)stannane is transmetallated by tin(IV) chloride stereoselectively to give a pent-1-en-3-yltin trichloride that reacts with aldehydes with excellent (E)-1,5-syn-stereocontrol, e.g. (3E)-1,5-syn-3-(tert-butyldimethylsilyloxymethyl)-5-(methoxymethoxy)-1-phenylhex-3-en-1-ol was the dominant product with benzaldehyde. The products from these reactions were taken through to more complex 2-substituted alk-2-enyl(tributyl)stannanes but only very low yields of the expected products were obtained from tin(IV) chloride mediated reactions of these stannanes and aldehydes. Nevertheless a stereoselective synthesis of 2-substituted 4-[(E)-2-alkoxypropylidene]tetrahydrofurans was developed.     

1,5-Stereocontrol in reactions of 5-benzyloxy-4-methylpent-2-enyl bromides with aldehydes mediated by Bi(0): synthesis of aliphatic compounds with 1,5-syn-related methyl groups

Treatment of the 5-benzyloxy-4-methylpent-2-enyl bromide 6 with the low valent bismuth species formed by reduction of bismuth(III) iodide with zinc powder generates an intermediate, which reacts with aldehydes with useful levels of 1,5-stereocontrol in favour of the 1,5-anti-(E)-isomers 4. These products were used to prepared aliphatic compounds with 1,5-syn-related methyl groups.     

Concerning the 1,5-stereocontrol in tin(iv) chloride promoted reactions of 4- and 5-alkoxyalk-2-enylstannanes: trapping intermediate allyltin trichlorides using phenyllithium

Transmetallation of the 5-benzyloxy-4-methylpent-2-en-1-yl(tributyl)- and -(triphenyl)stannanes 1 and 8 using tin(iv) chloride generates an allyltin trichloride that reacts with aldehydes to give (Z)-1,5-anti-6-benzyloxy-5-methylhex-3-en-1-ols 2. The allyltin trichloride believed to be the key intermediate in these reactions has been trapped by phenyllithium to give anti-5-benzyloxy-4-methylpent-1-en-3-yl(triphenyl)stannane 9. Transmetallation of this anti-5-benzyloxy-4-methylpent-1-en-3-yl(triphenyl)stannane 9 generated an allyltin trichloride that reacted with aldehydes to give the (Z)-1,5-syn-6-benzyloxy-5-methylhex-3-en-1-ols 23 and was trapped by phenyllithium to give syn-5-benzyloxy-4-methylpent-1-en-3-yl(triphenyl)stannane 24. Similar stereoselectivity was observed for tin(iv) chloride promoted reactions of this syn-5-benzyloxy-4-methylpent-1-en-3-yl(triphenyl)stannane 24 with aldehydes and with phenyllithium. The allyltin trichlorides generated by transmetallation of 4-hydroxy- and 4-benzyloxy-pent-2-enyl(triphenyl)stannanes 34 and 35 were similarly trapped by phenyllithium to give 4-hydroxy- and 4-benzyloxy-pent-1-en-3-ylstannanes 36 and 37 whose configurations were established by correlation with known compounds. This work confirmed the configurations of the intermediate allyltin trichlorides involved in tin(iv) chloride promoted reactions of 4- and 5-alkoxypent-2-enylstannanes with aldehydes and showed that the high levels of remote stereocontrol were due mainly to kinetically controlled transmetallation. A fuller mechanistic scheme is proposed for the reactions in the 5-benzyloxy-4-methylpent-2-enylstannane series together with relevant (119)Sn NMR data.     

Highly diastereoselective reactions of (E)-cinnamyl chloride with aldehydes mediated by tin and aluminium

The reactions of (E)-cinnamyl chloride with aldehydes in H₂O: THF: HBr in the presence of tin and aluminium powders proceed with very high stereoselectivity.     

Synthesis and characterization of N-[2-P(i-Pr)2-4-methylphenyl]2- (PNP) pincer tin(IV) and tin(II) complexes

N-[2-P(i-Pr)(2)-4-methylphenyl](2)(-) (PNP) pincer complexes of tin(IV) and tin(II), [(PNP)SnCl(3)] (2) and [(PNP)SnN(SiMe(3))(2)] (3), respectively, were prepared and characterized by X-ray diffraction, solution and solid state NMR spectroscopy, and (119)Sn M?ssbauer spectroscopy. Furthermore, (119)Sn cross polarization magic angle spinning NMR spectroscopic data of [Sn(NMe(2))(2)](2) are reported. Compound 2 is surprisingly stable toward air, but attempts to substitute chloride ligands caused decomposition.     

Tris(2-cyanoethyl)tin(IV) bromide and tris(2-cyanoethyl)tin(IV) iodide,their structure,properties and reactions with adenosine,AMP and ATP

Complexes [Sn(CH₂CH₂CN)₃I] (1) and [SnBr(CH₂CH₂CN)₃] (2) have been obtained by the oxidation reactions of hexakis(2-cyanoethyl)ditin(III) by means of iodine and bromine. The complexes have been characterized by NMR and IR spectroscopy methods and X-ray crystallography. Both compounds consist of zigzag single-strand chains with a bridging 2-cyanoethyl ligand coordinating via the CH₂ group and N atom. The tin atoms are in a distorted trigonal bipyramidal environment with bromo or iodo ligands and a nitrogen atom occupying the axial coordination sites. The Sn(1)–N(3i) distances in complexes 1 and 2 are considerably longer than the tin-equatorial ligand bonds. The molecular and electronic structures and IR spectra of [SnBr(CH₂CH₂CN)₃] mononuclear and [SnBr(CH₂CH₂CN)₃]₂ dinuclear fragments of the complex have been studied by the DFT B3LYP method. The calculated interatomic distances for the entity containing a five-coordinate tin atom agree well with those found crystallographically. The compounds in water solutions form trigonal bipyramidal complexes containing aqua and hydroxo axial ligands. The interaction of these complexes with adenosine, 5′-adenosine monophosphate and 5′-adenosine triphosphate has been investigated.     

Interaction of tin (IV) chloride with sulfolane and between tin (IV) chloride and lithium chloride in sulfolane solution

Tin (IV) chloride reacts with sulfolane (S) to form a cis-octahedral adduct SnCl₄·S₂. Solutions of lithium chloride and tin (IV) chloride in sulfolane contain the complex ions SnCl ₅ ^– and SnCl ₆ ^2– at 11 and 21 mole ratios of constituents, respectively. The complexes are characterized by conductimetry and by Mössbauer, IR, and Raman spectroscopy.     

Understanding the behavior of N-tosyl and N-2-pyridylsulfonyl imines in CuII-catalyzed aza-Friedel-Crafts reactions

The different behavior of N-tosyl imines and N-(2-pyridyl)sulfonyl imines in Cu (II)-catalyzed AFCR is described. DFT theoretical calculations on the mode of coordination of the copper atom to both types of substrates allow understanding this different reactivity.     

Rhodium(II) catalyzed multi-component reactions of aryldiazoacetates with titanium(IV) isopropoxide and imines

Rh₂(OAc)₄ catalyzed diazo decomposition of aryldiazoacetates in the presence of titanium(IV) isopropoxide generated oxonium ylide intermediates. Trapping of the oxonium ylide intermediates with imines occurred subsequently via a nucleophilic addition. The three-component reaction of aryldiazoacetates, titanium(IV) isopropoxide, and imines gave α-alkoxyl-β-amino acid derivatives with C-N/C-C bond formation in a single step. Extension of the study to a four-component reaction with in situ generated imine was also investigated.     

二[N,N-(1,5-亚戊基)氨荒酸]二氯化锡和二(对氟苄基)氯化锡N,N-(1,5-亚戊基)氨荒酸酯的合成、表征及晶体结构

合成了二[N,N-(1,5-亚戊基)氨荒酸]二氯化锡和二(对氟苄基)氯化锡N,N-(1,5-亚戊基)氨荒酸酯.用X射线单晶衍射测定了这两个化合物的晶体结构.化合物1为单斜晶系,空间群P21, a=0.8635(5) nm, b=0.8842(5) nm, c=1.2942(7) nm, β=102.177(9)°, Z=2, V=0.9659(9) nm3, Dc=1.719 g/cm3, μ=2.024 mm-1, R=0.0428, wR=0.0918.化合物2正交晶系,空间群Pbca, a=1.3616(13) nm, b=1.1679(11) nm, c=2.7603(3)nm, Z=8, V=4.389(7) nm3, Dc=1.612 g/cm3, μ=1.498 mm-1, R=0.0355, wR=0.0887.在化合物1中,锡原子呈六配位畸变八面体构型,化合物2的锡原子呈五配位畸变三角双锥构型.     

Copper(II) halide complexes with deprotonated N-(2-hydroxyethyl)ethylenediamine

Dimeric complexes of the type (CuLX)₂, where L is deprotonated N-(2-hydroxyethyl)ethylenediamine and X is either the chloride or bromide anion, were prepared. The complexes were characterized by elemental analyses, IR spectra, electronic spectra, ESR spectra and magnetic moments. Both complexes exhibit antiferromagnetic interactions.     

A chiral lead-free tin(IV)-based halide organic-inorganic semiconductor with dielectric switching and phase transition

Chiral organic-inorganic metal halide semiconductors (OIMHSs) have recently attracted numerous interests due to their unique chirality, structural tunability, and extensive physical properties. However, most reported chiral OIMHSs contain toxic lead, which will be a potential obstacle to their further applications. Herein, we successfully synthesized a novel chiral lead-free tin(IV)-based OIMHS [(R)-3-hydroxyquinuclidinium]₂SnCl₆ ([R-HQ]₂SnCl₆). It exhibits a wide band gap (E_g) of about 4.11 eV. Moreover, [R-HQ]₂SnCl₆ undergoes a phase transition around 330 K (T_c) and shows distinct dielectric switching characteristics with good repeatability. This work enriches the chiral lead-free OIMHS family and stimulates further exploration of chiral lead-free OIMHS switching materials     

Intramolecular heterocyclization of N-(pyrimidin-2-yl)imines of methyl trifluoropyruvate

The reactions of N-(pyrimidin-2-yl)imines of methyl trifluoropyruvate with trimethyl phosphite afforded methyl 3-fluoroimidazo[1,2-a]pyrimidin-2-carboxylates, which were transformed into N-substituted methyl 3-aminoimidazo[1,2-a]pyrimidine-2-carboxylates by the reactions with amines.     

Aryl transfer between Pd(II) centers or Pd(IV) intermediates in Pd-catalyzed domino reactions

A computational study has been performed to determine the mechanism of the key steps of Pd-catalyzed domino reactions in which C(sp2)-C(sp2) are formed from aryl and alkenyl halides. DFT calculations were done on model complexes of the proposed intermediates, with PH3 and H2O as ancillary ligands, to explore two possible mechanisms: the oxidative addition of aryl or alkenyl halides to palladacycles to give Pd(IV) intermediates, and the transmetalation-type reaction of aryl or alkenyl ligands between two Pd(II) centers, a palladacycle, and a Pd(II) complex formed by oxidative addition of aryl or alkenyl halides to Pd0. We have shown that oxidative addition of iodoethylene to Pd0 precursors is more favorable than oxidative addition to Pd(II) palladacycles, whereas transmetalation-type reactions between Pd(II) complexes are facile. Similar results were obtained with iodobenzene instead of iodoethylene and formamide as the ancillary ligand. These results suggest that Pd(IV) intermediates are not involved in these reactions.     

Syntheses and Crystal Structures of 1,5-Disubstituted 1,3,5-Hexahydro-triazine-2-（N-nitro）imines

The title compounds,C9H13ClN6O2S 1 and C15H17ClN6O2S 2,were synthesized and structurally characterized by elemental analysis,IR,1H NMR spectra and single-crystal X-ray diffraction.Compound 1 is in the monoclinic system,space group P21/c with a=13.7711(5),b=10.3883(4),c=9.7623(2),V=1344.47(8)3,Dc=1.506 g/cm3,C9H13ClN6O2S,Mr=304.76,F(000)=632,μ=0.448 mm-1,Z=4,S=1.084,R=0.0497 and wR=0.1328 for 2640 unique reflections(Rint=0.0787) with 2089 observed ones(I2σ(I)).Compound 2 belongs to the monoclinic system,space group P21/n with a=8.3828(5),b=14.5285(7),c=14.2456(4),V=1729.74(14)3,Dc=1.462 g/cm3,C15H17ClN6O2S,Mr=380.86,F(000)=792,μ=0.364 mm-1,Z=4,S=1.057,R=0.0598 and wR=0.1582 for 3384 unique reflections(Rint=0.0469) with 2833 observed ones(I2σ(I)).Compounds 1 and 2 are homologues and stabilized by intermolecular and intramolecular hydrogen bonds.Moreover,compound 2 containing C(2)-H(2)…π(thiazole) interaction is more stable than 1.