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Mathias Noltemeyer

Publications and source records attributed to Mathias Noltemeyer.

17 recordsLinked to original sources
PubMed2002

Mono- and disubstituted N,N-dialkylcyclopropylamines from dialkylformamides via ligand-exchanged titanium-alkene complexes.

Dibenzylformamide was treated with cyclohexylmagnesium bromide in the presence of either titanium tetraisopropoxide or methyltitanium triisopropoxide and a variety of cyclic and acyclic alkenes and alkadienes to give new mono- and disubstituted as well as bicyclic dialkylcyclopropylamines (Tables 1-3) in yields ranging from 18 to 90 % (in most cases around 55 %). 3-Benzyl-6-(N,N-dibenzylamino)-3-azabicyclo[3.1.0]hexane (10 a) and the orthogonally bisprotected 3-tert-butoxycarbonyl-6-(N,N-dibenzyl)-3-azabicyclo[3.1.0]hexane (10 d) as well as the analogous 6-(N,N-dibenzylamino)bicyclo[3.1.0]hexane (12) were obtained as pure exo diastereomers in particularly high yields (87, 90, and 88 %, respectively) from N-benzylpyrroline (15 a), N-Boc-pyrroline (15 d; Boc=tert-butyloxycarbonyl) and cyclopentene (19). 1,3-Butadiene (52) and substituted 1,3-butadienes were also aminocyclopropanated quite well to give 2-ethenylcyclopropylamines in good yields (51-64 %). Except for alkenyl- and aryl-substituted compounds, N,N-dibenzylcyclopropylamines can be debenzylated by catalytic hydrogenation to the primary cyclopropylamines as demonstrated for 10 a and 10 d to yield the fully deprotected 10 e (93 %) and mono-Boc-protected 10 f (98 %), respectively. The latter are interesting templates for combinatorial syntheses of libraries of small molecules with a well defined distance of 4.3 A between two nitrogen atoms.

Alkenes↗
PubMed2002

Synthesis and structures of [[HC(CMeNAr)(2)]Ge(S)X] (Ar = 2,6-iPr(2)C(6)H(3), X = F, Cl, Me): structurally characterized examples with a formal double bond between group 14 and 16 elements bearing a halide.

Treatment of [{HC(CMeNAr)2}GeX] (Ar = 2,6-iPr2C6H3, X = Cl (1), F (2)), with elemental sulfur at room temperature smoothly afforded the [{HC(CMeNAr)2}Ge(S)X] (X = Cl (3), F (4)). Compound 4 can also be obtained from 3 with the fluorination reagent Me3SnF. Reaction of 3 with MeLi led to the formation of [{HC(CMeNAr)2}Ge(S)Me] (5). Single-crystal X-ray structural analyses indicate compounds 3-5 are monomeric. The germanium centers adopt four coordinated sites and reside in distorted tetrahedral environment. Compounds 3 and 4 are structurally characterized examples with a formal double bond between group 14 and 16 elements bearing a halide.

Journal Article↗
PubMed2002

A new highly efficient three-component domino Heck-Diels-Alder reaction with bicyclopropylidene: rapid access to spiro[2.5]oct-4-ene derivatives.

Bicyclopropylidene (1) was found to surpass even methyl acrylate (17 a) in its rate of undergoing carbopalladation with aryl- or alkenylpalladium species, leading to substituted allylidenecyclopropanes 5, 7 and 10, mostly in high yields (37-78 %). These dienes and cross-conjugated trienes react in a Diels-Alder mode with dienophiles to give spiro[2.5]octenes 18 a-Ph, 18 b-Ph and 18 a-Vin, respectively, in good yields (89, 69 and 65 %). The overall transformation can be achieved as a one-pot three-component reaction with a variety of dienophiles to furnish the domino Heck-Diels-Alder products 18 regioselectively in most cases in good to very high yields (49-100 %). The reaction of 1 with iodobenzene (2-Ph) and 17 a gave 18 a-Ph in virtually quantitative yield-also on a gram scale-using only 1 mol % of catalyst, and even bromobenzene (22) gave 18 a-Ph in 59 % yield. Bicyclopropylidene (1), in the presence of palladium acetate/triphenylphosphane underwent rearrangement to allylidenecyclopropane (5-H), which in turn dimerized (73 %) in the absence of other reaction partners, or could be trapped by diethyl fumarate (17 c) to give the Diels-Alder adduct 18 c-H in 45 % yield. The coupling of oligoiodobenzenes with 1 and subsequent cycloaddition could be extended to a multicomponent reaction. In this way, 1,4-diiodobenzene (37), 1 and an alkyl acrylate gave the products 38 of a twofold Heck-Diels-Alder reaction in up to 87 % yield, 1,3,5-triiodobenzene (39) reacted in up to 72 % yield and ultimately 1,2,4,5-tetraiodobenzene (41) gave the fourfold domino Heck-Diels-Alder product 42 in 47 % isolated yield, in a single operation in which 12 new carbon-carbon bonds were formed.

Journal Article↗
PubMed2002

Syntheses, structures, and surface aromaticity of the new carbaalane [(AlH)(6)(AlNMe(3))(2)(CCH(2)R)(6)] (R = Ph, CH(2)SiMe(3)) and a stepwise functionalization of the inner and outer sphere of the cluster.

The reaction of the acetylene RC triple bond CH (R = Ph, CH(2)SiMe(3)) with an excess of AlH(3).NMe(3) in boiling toluene leads to the carbaalane [(AlH)(6)(AlNMe(3))(2)(CCH(2)R)(6)] (R = Ph 1, CH(2)SiMe(3) 2) in good yield. Treatment of 2 with BCl(3) under varying conditions gives the chlorinated products [(AlCl)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] 3 and [(AlCl)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(2)Cl)(6)] 4, respectively. The latter clearly demonstrates that the cluster can be stepwise functionalized within the inner and outer sphere. The X-ray single-crystal structures of 1, 2, and 4 have been determined. All compounds have in common that the central core consists of a cluster having eight aluminum and six carbon atoms. The bonding properties in this cluster are described as a new manifestation of three-dimensional surface aromaticity. Each Al(4)C fragment of the cube is formed by four bonds with three electron pairs, thus leading to a strong delocalization of the electrons. A phenomenological modeling using a three-dimensional Hückel scheme with fitted parameters to reproduce the energies from ab initio calculations revealed that the orbital scheme localized at one Al(4)C fragment possesses an orbital sextet with a large HOMO-LUMO gap. This is in line with the criteria of aromaticity. The idea of aromaticity was sustained also by qualitative valence bond reasons enumerating the different resonance structures by means of graph theoretical methods.

Journal Article↗
PubMed2002

Reactions of AlH(3) x NMe(3) with nitriles: structural characterization and substitution reactions of hexameric aluminum imides.

The reaction of AlH(3).NMe(3) with RCN proceeds with the evolution of trimethylamine and affords (HAINCH(2)R)(6) (R = Ph (1), p-MeC(6)H(4) (2), p-CF(3)C(6)H(4) (3)). Compounds 1 and 3 are characterized by single-crystal structural analysis. Compound 1 reacts with Me(3)SiBr as well as with PhC[triple bond]CH to give (XAINCH(2)Ph)(6) (X = Br (4), PhC[triple bond]C (5)). Structural data and other characterization data of compounds 4 and 5 show that all the hydridic hydrogen atoms in 1 have been replaced by bromine atoms and PhC[triple bond]C groups, respectively. Compounds 1-5 are potential precursors for the preparation of aluminum nitride. Crystals of 1 are rhombohedral, space group R3 macro, with a = 15.7457(13) A, b = 15.7457(13) A, c = 14.949(2) A, V = 3209.8(5) A(3), and Z = 3. Crystals of 3.(3)/(4)C(7)H(8) are triclinic, space group P1 macro, with a = 17.527(11) A, b = 18.894(12) A, c = 19.246(15) A, alpha = 96.11(7) degrees, beta = 102.23(4) degrees, gamma = 106.79(3) degrees, V = 5867(7) A(3), and Z = 4. Compound 4 crystallizes in the monoclinic space group P2(1)/c, with a = 14.175(4) A, b = 16.678(5) A, c = 10.731(3) A, beta = 106.82(2) degrees, V = 2428.6(11) A(3), and Z = 2. Compound 5. C(7)H(8) crystallizes in the monoclinic space group C2/c, with a = 25.842(5) A, b = 15.443(3) A, c = 20.699(4) A, beta = 105.88(3) degrees, V = 7945(3) A(3), and Z = 4.

Journal Article↗
PubMed2001

Nucleophilic Trapping of pi-Allylpalladium Intermediates Generated by Carbopalladation of Bicyclopropylidene: A Novel Three-Component Reaction Cyclopropyl Building Blocks in Organic Synthesis, Part 73. This work was supported by the Fonds der Chemischen Industrie and Bayer AG. We are indebted to Dr. B. Knieriem, Göttingen, for his careful proofreading of the final manuscript. Part 72: A. de Meijere, M. von Seebach, S. I. Kozhushkov, S. Cicchi, T. Dimoulas, A. Brandi, Eur. J. Org. Chem. 2001, in press; Part 71: A. de Meijere, S. I. Kozhushkov, D. Faber, V. Bagutskii, R. Boese, T. Haumann, R. Walsh, Eur. J. Org. Chem. 2001, in press.

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Journal Article↗
PubMed2000

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Journal Article↗
PubMed1999

Chameleon Thermal Behavior of Cycloadducts of Nitrones to Methyl 2-Chloro-2-cyclopropylidene- and 2-Chloro-2-spiropentylideneacetates.

Methyl 2-chloro-2-cyclopropylideneacetate (2) and its spiropentane analogue 3 cycloadd to dihydroisoquinoline N-oxide (9), pyrroline N-oxide (12), and C-phenyl-N-methylnitrone (16) to give 5-spirocyclopropaneisoxazolidines in good yields (58-93%). The thermal behavior of the 5-spirocyclopropaneisoxazolidines is rather differentiated, depending strongly on the constitution of the nitrone and the solvent. As nitrone 9 has the tendency to undergo cycloreversion reactions, the ketoamide rearrangement products 20 and 21 from its cycloadduct derive from the thermodynamically favored 4-spirocyclopropaneisoxazolidine regioisomers formed after the cycloreversion process. In DMSO as solvent different rearrangement processes take place, leading to benzoindolizinones in modest yields (15-21%). The cycloadducts from 12 and 16 undergo a cyclopropyl to cyclobutyl ring enlargement facilitated by the presence of a chlorine substituent on the carbon alpha to the spirocyclopropane ring. Whereas these compounds from nitrone 16 demonstrated an unusual stability, those from nitrone 12 undergo a cascade rearrangement to yield indolizinone derivatives 34, 35 cleanly (73-83% yield). This overall transformation offers a new method for the synthesis of the indolizine skeleton.

Journal Article↗
PubMed1996

Organometallic Fluorides of Zirconium and Hafnium in the Synthesis of Carboxylate Complexes: Molecular Structures of [{(eta(5)-C(5)Me(5))ZrF(OCOCF(3))(2)}(2)] and [(eta(5)-C(5)Me(5))(2)Zr(OCOCF(3))(2)].

The reaction of [(eta(5)-C(5)Me(5))ZrF(3)] and [(eta(5)-C(5)Me(5))HfF(3)] with Me(3)SiOCOCF(3) yields the dinuclear complexes [{(eta(5)-C(5)Me(5))ZrF(OCOCF(3))(2)}(2)] (1) and [{(eta(5)-C(5)Me(5))HfF(OCOCF(3))(2)}(2)] (2), regardless of the molar ratio employed. [(eta(5)-C(5)Me(5))(2)ZrF(2)] reacts with 1 and 2 equiv of Me(3)SiOCOCF(3) to form the mononuclear compounds [(eta(5)-C(5)Me(5))(2)Zr(OCOCF(3))(2)] (3) and [(eta(5)-C(5)Me(5))(2)ZrF(OCOCF(3))] (4), respectively. The molecular structures of 1 and 3 have been determined by single-crystal X-ray analysis: 1, triclinic, P&onemacr;, a = 9.508(3) Å, b = 11.002(4) Å, c = 17.528(3) Å, alpha = 78.55(4), beta = 76.80(2), gamma = 87.51(2) degrees, V = 1750(1) Å(3), Z = 2, R = 0.0378; 3, monoclinic, C2/c, a = 18.553(4) Å, b = 9.110(2) Å, c = 16.323(3) Å, beta = 114.88(3) degrees, V = 2503(1) Å(3), Z = 4, R = 0.0457. Compound 1 shows bridging bidentate and chelating carboxylate ligands as well as bridging fluorine atoms. The zirconium atoms are seven coordinated and have an 18-electron configuration. X-ray studies of 3 reveal two structural components where the carboxylate ligands coordinate in a monodentate (major component) and a chelating manner (minor component).

Journal Article↗
PubMed1996

First Mixed Fluoro-Chloro Group 4 Organometallics: Synthesis and Spectroscopic and Structural Characterization of [{(C(5)Me(5))ZrF(2)Cl}(4)], [{(C(5)Me(5))HfF(2)Cl}(4)], [(C(5)Me(5))(4)Zr(4)(&mgr;-F)(2)(&mgr;-F(2))(2)(&mgr;-Cl)(2)Cl(4)], [(C(5)Me(5))(4)Hf(4)(&mgr;-F)(2)(&mgr;-F(2))(2)(&mgr;-Cl)(2)Cl(4)], [(C(5)Me(4)Et)(2)ZrClF], and [(C(5)Me(5))(2)HfClF].

Tetrameric [{(C(5)Me(5))MF(3)}(4)] (M = Zr, Hf) react smoothly with Me(3)SiCl in CH(2)Cl(2) at room temperature to give [{(C(5)Me(5))ZrF(2)Cl}(4)] (1) and [{(C(5)Me(5))HfF(2)Cl}(4)] (2), respectively, in high yield. Treatment of [{(C(5)Me(5))MF(3)}(4)] (M = Zr, Hf) with Me(2)AlCl in toluene gives mixtures of 1 and [(C(5)Me(5))(4)Zr(4)(&mgr;-F)(2)(&mgr;-F(2))(2)(&mgr;-Cl)(2)Cl(4)] (3), and 2 and [(C(5)Me(5))(4)Hf(4)(&mgr;-F)(2)(&mgr;-F(2))(2)(&mgr;-Cl)(2)Cl(4)] (4), respectively, in an approximately 1:1 molar ratio. Metallocene type complexes [(C(5)Me(4)Et)(2)ZrCl(2)] and [(C(5)Me(5))(2)HfCl(2)] react with 1 equiv of Me(3)SnF to give [(C(5)Me(4)Et)(2)ZrClF] (5) and [(C(5)Me(5))(2)HfClF] (6), respectively. The complexes 1-6 were characterized by spectroscopic methods ((1)H and (19)F NMR and mass spectroscopy). The solid state structures of 1, 3, and 5 were determined by single-crystal X-ray diffraction analyses.

Journal Article↗