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Karl W Törnroos

Publications and source records attributed to Karl W Törnroos.

At least 19 recordsLinked to original sources
PubMed2007

Asymmetric synthesis of cyclopropylamines starting from N-sulfinyl alpha-chloro ketimines.

Treatment of novel chiral N-sulfinyl alpha-chloro ketimines with Grignard reagents resulted in the synthesis of chiral N-(1-substituted cyclopropyl)-tert-butanesulfinamides in acceptable to good yields and diastereoselectivity via 1,3-dehydrohalogenation and subsequent addition of the Grignard reagent to the intermediate cyclopropylideneamine. Only in the case of allylmagnesium chloride did the reaction lead to aziridines in high yield. Further deprotection toward N-unprotected 1-substituted cyclopropylamines was established, and the absolute configuration was determined. [reaction: see text].

Cyclopropanes↗
PubMed2006

Interplay of spin conversion and structural phase transformations: re-entrant phase transitions in the 2-propanol solvate of tris(2-picolylamine)iron(II) dichloride.

Crystal structures, magnetic and thermodynamic properties of the spin-crossover compound tris(2-picolylamine)iron(II) dichloride (with 2-propanol solvent molecules) have been measured in the temperature range from 15 to 293 K. X-ray diffraction, SQUID, and calorimetric experiments all showed two first-order phase transitions with hysteresis loops, a narrow one at T(1) approximately 196 K and a broad, triangular one covering the range 153<T(2)<166 K. Crystal structures were analysed at fourteen temperatures in a cooling cycle and at seven temperatures in a heating cycle. They reveal a complex, temperature-dependent ordering behaviour of both the complex cations and the alcohol molecules. A phenomenological model accounting for spin conversion, solvent ordering and coupling between the two processes describes the observed phase transitions and ordering phenomena reasonably well. Similarities and differences in the behaviour of the corresponding ethanol solvate with the same crystal architecture are discussed. It is concluded that spin-crossover behaviour depends as much on molecular properties as it does on intermolecular interactions, both of the spin active and the spin inactive components.

Journal Article↗
PubMed2006

Synthesis of 2-chloro-2-imidoylaziridines via aza-Darzens-type reaction of 3,3-dichloro-1-azaallylic anions and N-(arylsulfonyl)imines.

3,3-Dichloro-1-azaallylic anions, generated by deprotonation of alpha,alpha-dichloroketimines 10 with lithium diisopropylamide, reacted with N-sulfonylaldimines 7 to produce the Mannich-type products N-[2,2-dichloro-3-(N-alkylimino)-1,3-diarylpropyl]benzenesulfonamides 11. The latter stable compounds were hydrolyzed at the imino functionality to afford N-[2,2-dichloro-3-oxo-1,3-diarylpropyl]benzenesulfonamides 12 in excellent yields. N-[2,2-Dichloro-3-(N-alkylimino)-1,3-diarylpropyl]benzenesulfonamides 11 were cyclized to cis-3-aryl-2-chloro-2-imidoylaziridines 19 in 81-99% yield with high diastereoselectivity, representing a novel and readily available class of stable 2-chloroaziridines. Finally, a highly stereoselective entry to 2-(aminomethyl)-2-chloroaziridines 27 (70-98% yield; de > 95-99) was worked out from the reaction of cis-3-aryl-2-chloro-2-imidoylaziridines 19 and sodium cyanoborohydride in the presence of acetic acid. The latter 2-(aminomethyl)aziridines 27 represent stereochemically defined small azaheterocyclic rings which were scarcely reported in the literature.

Anions↗
PubMed2006

"Ionic carbenes": synthesis, structural characterization, and reactivity of rare-Earth metal methylidene complexes.

Treatment of mixed chloride tetramethylaluminate polynuclear clusters {Cp*Y[(mu-Me)2AlMe2](mu-Cl)}2 and {Cp*6La6[(mu-Me)3AlMe]4(mu3-Cl)2(mu2-Cl)6} with toluene/THF solutions produces "aluminum-free" methylidene complexes [Cp*3Ln3(mu-Cl)3(mu3-Cl)(mu3-CH2)(THF)3] (Ln = Y, La). The trinuclear methylidene complexes are isostructural in the solid state and feature a sterically well-shielded Schrock-type nucleophilic CH22- unit, which is prone to Tebbe-like methylenation reactions with ketones and aldehydes. The rapid polymerization of gamma-valerolactone reveals intrinsic rare-earth metal reactivity.

Journal Article↗
PubMed2006

Use of alpha-chlorinated N-(tert-butanesulfinyl)imines in the synthesis of chiral aziridines.

[reaction: see text] Reaction of chiral alpha-chloro tert-butanesulfinyl aldimines with Grignard reagents efficiently afforded beta-chloro N-sulfinamides in high diastereomeric excess. The latter compounds were cyclized toward the corresponding chiral aziridines in a high-yielding one-pot reaction or after separate treatment with base. The diastereoselectivity obtained in the newly synthesized beta-chloro sulfinamides is explained via the coordinating ability of the alpha-chloro atom with magnesium resulting in the opposite stereochemical outcome as generally observed for nonfunctionalized N-sulfinyl imines.

Journal Article↗
PubMed2006

Novel synthesis of cis-3,5-disubstituted morpholine derivatives.

1-tert-Butyl-2-(allyloxymethyl)aziridine has been transformed for the first time diastereoselectively into cis-3,5-di(bromomethyl)-4-tert-butylmorpholine via an electrophile-induced ring closure using bromine in dichloromethane. The latter morpholine has been used as a substrate for the synthesis of the corresponding 3,5-di(methoxymethyl)morpholine and 3,5-di(cyanomethyl)morpholine upon nucleophilic displacement of both bromo atoms. Further evaluation of this protocol toward the synthesis of 4-arylmethyl- and 4-alkylmethyl-3,5-di(bromomethyl)morpholines showed that the premised cyclization of the corresponding 2-(allyloxymethyl)aziridines into 3,5-di(bromomethyl)morpholines only proceeded well for the N-neopentylmorpholine, which was subsequently transformed into a 3-oxa-7-thia-9-azabicyclo[3.3.1]nonane derivative. Also, in some other cases, the desired 3,5-di(bromomethyl)morpholines were isolated in low yields and transformed into the corresponding 3,5-di(cyanomethyl)morpholines.

Aziridines↗
PubMed2006

Multiple C-H bond activation in group 3 chemistry: synthesis and structural characterization of an yttrium-aluminum-methine cluster.

Complete donor-induced alkylaluminate cleavage of halfmetallocene complex Cp*Y(AlMe4)2, that is, treatment of Cp*Y(AlMe4)2 with 2 equiv of diethyl ether, produces [Cp*Y(mu2-Me)2]3 in high yield (95%). In contrast, the equimolar reaction of Cp*Y(AlMe4)2 with diethyl ether reproducibly formed complex [Cp*4Y4(mu2-CH3)2{(CH3)Al(mu2-CH3)2}4(mu4-CH)2] in low yield (10-30%) via a multiple C-H bond activation. The synthesis of the heterooctametallic yttrium-aluminum-methine cluster was also accomplished in moderate yield (47%) by the equimolar reaction of discrete Cp*Y(AlMe4)2 and [Cp*Y(mu2-Me)2]3 in the absence of any donor solvent and "free" AlMe3. This gives strong evidence that preformed heterometal-bridged Y-CH3-Al moieties are prone to multiple hydrogen abstraction in the presence of a highly basic reagent such as [Cp*Y(mu2-Me)2]3. The monocylopentadienyl complexes [Cp*Y(mu2-Me)2]3 and [Cp*4Y4(mu2-CH3)2{(CH3)Al(mu2-CH3)2}4(mu4-CH)2] were structurally characterized.

Journal Article↗
PubMed2005

Synthesis and structural characterization of scandium SALEN complexes.

A series of heteroleptic scandium SALEN complexes, [(SALEN)Sc(mu-Cl)]2 and (SALEN)Sc[N(SiHMe2)2] is obtained via amine elimination reactions using [Sc(N(i)Pr2)2(mu-Cl)(THF)]2 and Sc[N(SiHMe2)2]3(THF) as metal precursors, respectively. H(2)SALEN ligand precursors comprising H2Salen [(1,2-ethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H2Salpren [(2,2-dimethylpropanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H2Salcyc [(1R,2R)-(-)-1,2-cyclohexanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] and H2Salphen [((1S,2S)-(-)-1,2-diphenylethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] are selected according to solubility and ligand backbone variation ("=N-(R)-N=" bite angle) criteria. Consideration is given to the feasibility of [Cl --> NR2] and [N(SiHMe2)2--> OSiR3] secondary ligand exchange reactions. X-ray crystal structure analyses of donor-free (Salpren)Sc(N(i)Pr2), (R,R)-(Salcyc)Sc[N(SiHMe2)2], (Salen)Sc(OSi(t)BuPh2) and (Salphen)Sc(OSiH(t)Bu2) reveal (i) a very short Sc-N bond distance of 2.000(3) A, (ii) weak beta(Si-H)(amido)-Sc agostic interactions and (iii) an exclusive intramolecularly tetradentate and intrinsically bent coordination mode of the SALEN ligands with angle(Ph,Ph) dihedral angles and Sc-[N(2)O(2)] distances in the 124.27(9)-127.7(3) degrees and 0.638(1)-0.688(1) A range, respectively.

Journal Article↗
PubMed2005

[LnIIAlIII2(alkyl)8]x: donor addition instead of donor-induced cleavage.

(SmAl2Me8)x and (SmAl2Et8)x are obtained via a silylamide elimination reaction from Sm[N(SiMe3)2]2(THF)2 and excess AlR3 (R = Me, Et); (LnAl2Et8)x (Ln = Sm, Yb) react with THF, pyridine, and 1,10-phenanthroline to form the first donor adducts of homoleptic peralkylated Ln-Al heterobimetallic complexes.

Journal Article↗
PubMed2005

Co-crystallized cis and trans isomers of dichlorobis(2-picolylamine)iron(II).

The octahedral cis and trans isomers of dichlorobis(2-picolylamine)iron(II), [FeCl2(C6H8N2)2], co-crystallize in a 1:1 ratio. The cis isomer lies on a twofold axis, whereas the trans isomer lies on an inversion centre. The structure is fully ordered, with both Fe atoms in a pure high-spin state. The Fe, Cl and N(H2) atoms of both isomers lie in the same plane, allowing all Cl and amine H atoms to be engaged in extensive two-dimensional hydrogen bonding. The hydrogen-bonded layers are interconnected through pi-pi interactions between the pyridine rings. Searches in the Cambridge Structural Database uncover very few examples of such isomer co-existence.

Journal Article↗
PubMed2003

A synthetic zinc tellurium oxochloride, Zn2(TeO3)Cl2.

Single crystals of dizinc tellurium dichloride trioxide, Zn(2)(TeO(3))Cl(2), were synthesized via a transport reaction in sealed evacuated glass tubes. The compound has a layered structure in which the building units are [ZnO(4)Cl] square pyramids, distorted [ZnO(2)Cl(2)] tetrahedra and [TeO(3)E] tetrahedra (E is the 5s(2) lone pair of the Te(IV) atom), joined through shared edges and corners to form charge-neutral layers. Cl atoms and Te-atom lone pairs protrude from the surfaces of each layer towards adjacent layers, and the layers are held together by dispersion forces only. The compound is isostructural with the synthetic compound CuZn(TeO(3))Cl(2) and the mineral sophiite, Zn(2)(SeO(3))Cl(2).

Journal Article↗
PubMed2002

(n-Nitrophenyl)acetonitrile, with n = 2, 3 and 4.

The molecular structures of the three title nitro-substituted phenylacetonitriles, C(8)H(6)N(2)O(2), at 123 K show that the molecules are linked together very differently. In the 2- and 4-nitro compounds, there are both O...H and N(cyano)...H interactions, whereas the crystal lattice of the 3-nitro compound is essentially built up by O...H interactions. The O atoms seem to prefer the aromatic H atoms, while the cyano N atoms prefer the methylene H atoms. The phenyl-nitro torsion angles are -19.83 (13), -5.69 (12) and -2.88 (12) degrees, while the phenyl-cyanomethyl torsion angles are -62.27 (12), -147.99 (9) and -16.75 (14) degrees in the 2-, 3- and 4-NO(2)-substituted compounds, respectively.

Journal Article↗
PubMed2002

[4-(Trifluoromethyl)phenyl]acetonitrile.

The crystal structure of the title compound, C(9)H(6)F(3)N, at 123 K contains molecules linked together via several C-H...F and C-H...N contacts, the strongest of which are 2.58 and 2.65 A, respectively. Apparently, an F atom in the CF(3) group is able to compete with a cyano N atom for aromatic H atoms but is less prone to interact with the more acidic methylene H atoms. The Ph-CH(2)CN torsion angle is -6.4 (2) and the planar phenyl ring exhibits a typical deformation of the endo angles at the ipso-C atoms, due to the difference in the electron-withdrawing power of the CF(3) and CH(2)CN substituents.

Journal Article↗