Hydroborierung von 3-methyl-1,3-butadien mit 1,2:1,2-bis(tetramethylen)diboran(6)

The nature of the hydroboration product obtained from 3-methyl-1,3-butadiene and 1,2 : 1,2-bis(tetramethylene)diborane(6) (1) allows for the discussion of the reaction mechanism. The hydroboration proceedsby retention of the cyclic structure in the first step, followed by exchange of BH and BC bonds and final cyclic hydroboration to give 1-(boracyclopentyl)-4-(3-methylboracyclopentyl)butane (5). The structural assignment of 5 is based on ¹H, ¹¹B and ¹³C NMR data.     

Influence of the electrical parameters on the fabrication of copper nanowires into anodic alumina templates

Metallic copper nanowires have been grown into the pores of alumina membranes by electrodeposition from an aqueous solution containing CuSO₄^.and H₃BO₃ at pH 3. In order to study the influence of the electrical parameters on growth and structure of nanowires, different deposition potentials (both in the region where hydrogen evolution reaction is allowed or not) and voltage perturbation modes (constant potential or unipolar pulsed depositions) were applied. In all cases, pure polycrystalline Cu nanowires were fabricated into template pores, having lengths increasing with the total deposition time. These nanowires were self-standing, because they retain their vertical orientation and parallel geometry even after total template dissolution.However, the electrical parameters influence the growth rate, length uniformity and crystal size of the nanowires. Continuous electrodeposition resulted in higher growth rates but less uniform lengths of nanowires grown inside different membrane pores, whilst a square pulse deposition produced a slower growth but quite uniform lengths. Also the grain size, of the order of 50 nm, was slightly influenced by the potential perturbation mode.     

Benzazole-N(SINGLE BOND)BH3 adducts. Reductive transposition of 2-benzimidazole, 2-benzothiazole,and 2-benzoxazole N(SINGLE BOND)BH3 adducts to 1,3,2-benzimidazaborole, 1,3,2-benzoxaborole,and 1,3,2-benzothiazaborole

1,3,2-Benzimidazaborole, 1,3,2-benzoxaborole, and 1,3,2-benzothiazaborole were synthesized from the corresponding 2-benzazole N(SINGLE BOND)BH₃ and 2-benzazole S(SINGLE BOND)BH₃ adducts through a reductive transposition from the isolobal fragment X(SINGLE BOND)C(sp²) (DOUBLE BOND) N(sp²) (SINGLE BOND) B(sp³) (X (DOUBLE BOND) N, O, S) to the fragment X(SINGLE BOND)B(sp²) (DOUBLE BOND) N(sp²) (SINGLE BOND) C(sp³). N(SINGLE BOND)BH₃ substitution shifts to lower frequencies 4-H, C-3a, and C-7a resonances. The X-ray diffraction analysis of 2-(o-methoxyphenyl)benzothiazole N(SINGLE BOND)BH₃ adduct is reported. Two new tetracyclic boron-bridged compounds were observed as by-products (6,9-(ethyl)-diaza-2-oxa-1-bora[3,4,7,8]-dibenzobycyclo[4.3.0]-nona-3,7-diene, 6d, and 8-aza-9-oxa-2-thia-1-bora-[3,4,7,8]dibenzobycyclo[3.4.0]nona-3,7-diene, 15d, when 2-(o-methoxyphenyl)-1-ethylbenzimidazole-BH₃ 6b and 2-(o-methoxyphenyl)-benzothiazole-BH₃ 15b adducts were heated. © 1996 John Wiley & Sons, Inc.     

Aminophosphanes with bulky amino groups: Molecular structure,coupling constants 1J(31P, 15N) and 2J(31P, 29Si), and isotope‐induced chemical shifts 1Δ14/15N(31P)

The preferred conformation of aminophosphanes with bulky amino groups ( 1–20 ) was determined by NMR spectroscopy in solution, in two cases in the solid state ( 11,17 ) and in one case ( 11 ) by X‐ray crystallography. Trimethylsilylaminodiphenylphosphanes Ph₂PN(R)SiMe₃ (R = Bu ( 1 ), Ph ( 2 ), 2‐pyridyl ( 3 ), 2‐pyrimidyl ( 4 ), Me₃Si ( 5 )), amino(chloro)phenylphosphanes Ph(Cl)PNRR′ (R = Bz, R′ = Me ( 6 ), R = Bz, R′ = ^tBu ( 7 ), R = Et, R′ = Ph ( 8 )), amino(chloro)tert‐butylphosphanes ^tBu(Cl)PNRR′ (R = R′ = ⁱPr ( 9 ), R = Me, R′ = ^tBu ( 10 ), R = Bz, R′ = ^tBu ( 11 ), R = H, R′ = ^tBu ( 12 ), R = Et, R′ = Ph ( 13 ), R = ⁱPr, R′ = Ph ( 14 ), R = Bu, R′ = Ph ( 15 ), R = Bz, R′ = Ph ( 16 ), R = R′ = Ph ( 17 ), R = R′ = Me₃Si ( 18 )), 3‐tert‐butyl‐2‐chloro‐1,3,2‐oxazaphospholane ( 19 ), and benzyl(tert‐butyl)aminodichlorophosphane ( 20 ) were studied by ¹H, ¹³C, ¹⁵N, ²⁹Si, and ³¹P NMR spectroscopy. In all cases, the more bulky substituent at the nitrogen atom prefers the syn‐position with respect to the assumed orientation of the phosphorus lone pair of electrons. Many of the derivatives studied adopt this preferred conformation even at room temperature. Numerous signs of coupling constants ¹J(³¹P, ¹⁵N), ²J(³¹P, ¹³C), and ²J(³¹P, ²⁹Si) were determined. Low temperature NMR spectra were measured for derivatives for which rotation about the P N bond at room temperature is fast, showing the presence of two rotamers at low temperature. The respective conformation of these rotamers could be assigned by ¹³C, ¹⁵N, and ³¹P NMR spectroscopy. Isotope‐induced chemical shifts ¹Δ^15/14N(³¹P) were determined for all compounds at natural abundance of ¹⁵N by using Hahn‐echo extended polarization transfer experiments. The molecular structure of 11 in the solid state reveals pyramidal surroundings of the nitrogen atom and mutual trans‐positions of the tert‐butyl groups at phosphorus and nitrogen. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:667–676, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10084     

1,4,7,8-Triazaborabicyclooctanes—first examples of new boron heterocycles [1,2]

The first examples of 1,7,1,4,7,8-dialkyltriazaborabicyclo[3.3.0]octanes 1–3 [R = isopropyl ( 1 ), R = 1-phenylbenzyl (2) , R = 1-methylbenzyl (3) ] are reported. The bulky substituents prevent dimerization and make the syntheses feasible. The structures and conformations of the new compounds were studied by NMR spectroscopy. A chiral bicycle 3 (R,R) was also prepared.     

Phosphorus heterocycles from 2‐(2‐hydroxyphenyl)‐1H‐benzimidazole

Sixteen different P(III) and P(V) heterocycles derived from 2‐(2‐hydroxyphenyl)‐1H‐benzimidazole ( 1 ) are reported. In these heterocycles the phosphorus atom is part of a six‐membered unsaturated ring. They were mainly studied by multinuclear NMR. The X‐ray diffraction of 3,4‐ benzimidazole‐5,6‐benzo‐2‐dimethylamino‐2‐seleno‐ 1,3,2‐oxazaphosphorinane is reported. Phosphoranes derived from 1 and 3,5‐di‐tert‐butylcatechol, and bearing Cl, NMe₂, or phenyl as substituent at phosphorus are presented. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:307–320, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20021     

Cobalt(II), nickel(II) and copper(II) compounds derived from template reactions of enantiomerically pure 2-amino-thiazoles

Herein we report the syntheses and structural analyses of three coordination compounds Co(L)₂ (3), Ni(L)₂, (4) and Cu(L)₂ (5) (L = bis[(4R,5R)-4-methyl-5-phenyl-4,5-dihydro-thiazol-2-yl]-amine) prepared by template reactions from the optically active ligand (4R,5R)-4-methyl-5-phenyl-4,5-dihydro-thiazol-2-yl-amine (1) and CoCl₂·6H₂O, NiBr₂·3H₂O or Cu(OAc)₂·H₂O The template reactions involve the condensation of two molecules of thiazol-2-yl-amine and elimination of one NH₃. The resulting bidentate ligand coordinates to the metal ion through the imine nitrogen atoms forming a six-membered ring, presenting an electronic delocalization which averages the four M–N bond lengths. The distorted tetrahedral geometry of the metal atoms gives place to complex electronic spectra for compounds 3–5. A mixed ionic compound (6) formed by three cations (4S,5S)-3,4-dimethyl-5-phenyl-thiazolidin-2-ylidene ammonium, one dianion tris-(thiocyano)bromide cobaltate and one bromide, obtained from reaction of (4S,5S)-3,4-dimethyl-5-phenyl-thiazolidin-2-ylidene ammonium thiocyanate (2) and CoBr₂ is also described. Compounds 3–6 were characterized in the solid state by UV–Vis–NIR and IR spectroscopy, mass spectrometry and X-ray diffraction analyses. Metal···H–C, S···H–C interactions were observed in 3–6, whereas in 6, also Br···H–N, Br···H–C and Br···S, S···S short contacts were found.     

Berry exchange coordinate geometry in 3-methyl-2-hydroxycyclopenten-1-one tin esters

Three new penta- and hexacoordinated tin compounds (1-3) were prepared from PhSnCl₃, Ph₂SnCl₂ and Ph₃SnOH and 3-methyl-2-hydroxy-2-cyclopenten-1-one (L). Compounds 1-3 were characterized by IR, mass spectra, elemental analysis, ¹H, ¹³C, and ¹¹⁹Sn NMR. The ligand acts as a bidentate giving the tin esters and coordinating the tin by the carbonyl group. Compound 1 (PhSnCl₂L · EtOH) has an hexacoordinated tin atom, with an octahedral distorted geometry, which is a stereogenic center. Compounds 2 (Ph₂SnClL) and 3 (Ph₃SnL) have pentacoordinated tin atoms. The structures were determined by X-ray diffraction analyses. In the solid state 1 presents a racemic pair, linked by strong hydrogen bonds and 2 and 3 “Berry exchange coordinate” geometry.     

Heptacoordinated diphenyllead; hexa- and pentacoordinated triphenyllead and tin compounds derived from 5H-benzimidazo[1,2-c]quinazoline-6-thione

Heptacoordinated diphenyllead; hexa- and pentacoordinated triphenyllead and tin compounds derived from 5H-benzimidazo[1,2-c]quinazoline-6-thione are reported. The same molecular structures were found in solution by ¹¹⁹Sn and ²⁰⁷Pb NMR and in the solid state by X-ray diffraction analysis. The ligand was bound through S and N giving a four-membered ring. Due to the tension of the chelate ring in the penta- and hexacoordinated compounds, the nitrogen approaches the metal atom from an oblique direction giving a weak coordination. Hexacoordinated metal atoms were obtained by Lewis bases coordination to the polycyclic tin and lead compounds, which was possible because the M-phenyl groups form a cavity that allows the bases to approach from the opposite direction to the sulfur atom. In some crystals, two molecules formed a cavity where a solvent molecule was included. A heptacoordinated diphenyllead bound to two ligands and having the less common pentagonal bipyramidal geometry and cis-mer configuration with two sulfur atoms lying very close together was obtained.     

In‐time and in‐space tandem mass spectrometry to determine the metabolic profiling of flavonoids in a typical sweet cherry (Prunus avium L.) cultivar from Southern Italy

This paper presents a comprehensive analytical methodology, based on ‘in‐time’ and ‘in‐space’ tandem mass spectrometry (MS) techniques, to identify and quantify flavonoid compounds in a typical Italian sweet cherry cultivar (cv. Ferrovia). Five anthocyanins, four flavan‐3‐ols and nine flavonols were determined by means of hyphenated high‐performance liquid chromatography – multi‐stage MS (HPLC‐MSⁿ) analyses (MSⁿ up to MS⁴), among which quercetin‐3‐O‐rutinoside‐7‐O‐glucoside, kaempferol‐3‐O‐rutinoside‐7‐O‐glucoside, quercetin‐3‐O‐galactosyl‐rhamnoside and quercetin‐3‐O‐coumaroylglucoside were tentatively identified in sweet cherries for the first time. Ultrafast HPLC and tandem MS (UHPLC‐MS/MS) analyses through multiple reaction monitoring experiments showed that cyanidin‐3‐O‐rutinoside and cyanidin‐3‐O‐glucoside were the main anthocyanins of cv. Ferrovia at maturity. Moreover, consistent levels of catechin and epicatechin as well as quercetin‐3‐O‐rutinoside and kaempferol‐3‐O‐rutinoside were also found. Because flavonoids have been ascribed as potential health‐promoting compounds, gathered findings provide new insight into the knowledge of the quali‐quantitative profile of these phytochemicals into a widespread fruit such as sweet cherry. Copyright © 2014 John Wiley & Sons, Ltd.