Showing papers by "George M. Sheldrick published in 1983"
TL;DR: In this paper, a 2:1 adduct of t-butylamino-diorganylfluorosilanes with aluminum trichloride in petroleum ether was derived.
26 citations
24 citations
TL;DR: In this paper, the 1 : 1 adduct of Tin Tetrachloride and Bis(trimethylsilyl)sulfur diimide was shown to function as a bidentate ligand.
Abstract: Sowohl (CH3)3SiNSO als auch (CH3)3SiNSNSi(CH3)3 reagieren mit SnCl4 unter Bildung des 1 : 1-Adduktes (CH3)3SiNSNSi(CH3)3 · SnCl4 (1). Eine Einkristallrontgenstrukturanalyse zeigt, das das Schwefeldiimid als zweizahniger Ligand fungiert. 1 kristallisiert in der Raumgruppe P21/m mit den Zellkonstanten a = 663.7(1), b = 1998.9(3), c = 696.7(1) pm und β = 94.18(2)°.
Adduct of Tin Tetrachloride and Bis(trimethylsilyl)sulfur Diimide
Both (CH3)3SiNSO and (CH3)3SiNSNSi(CH3)3 react with SnCl4 to yield the 1 : 1 adduct (CH3)3SiNSNSi(CH3)3 · SnCl4 (1). An X-ray analysis shows that the sulfur diimide functions as a bidentate ligand. 1 crystallizes in the space group P21/m with unit-cell constants a = 663.7(1), b = 1998.9(3), c = 696.7(1) pm, and β = 94.18(2)°.
23 citations
TL;DR: In this article, the cucurbitacin glycosides B(8), C(3), D(9), E(4), F(5), G(6), and H(10), as well as the known compound datiscoside (1) have been isolated and characterized.
Abstract: Datisca glomerata has been systematically fractionated by following cellular toxicity in an effort to identify previously uncharacterized cytotoxic principles. Several new cucurbitacin glycosides, including datiscosides B(8), C(3), D(9), E(4), F(5), G(6), and H(10) and the known compound datiscoside (1), as well as cucurbitacins B(11), D(2), and F(7) have been isolated and characterized. Structures were assigned to the compounds on the basis of their high field 1H n.m.r., 13C n.m.r., high-resolution mass spectra (CI, EI, and FD) and chemical interconversions. The structure of datiscoside C(3) was independently established by single-crystal X-ray analysis at 193 and 293 K.
22 citations
TL;DR: AuClR2(dppm) with AgClO4 gives [R2ClAu(dplm)AuPPh3] as discussed by the authors.
Abstract: Reactions of gold(III) complexes of the types [AuClR2(dppm)] and [AuR3(dppm)](R = C6F5, dppm = bis(diphenylphosphino)methane] with other gold complexes, such as [Au(O3ClO)(PPh3)], [Au(C6F5)(tht)], [AuCl(tht)], or [AuCl3(tht)](tht = tetrahydrothiophene) which contain a readily displaceable ligand (O3ClO– or tht), lead to the formation of cationic binuclear complexes of the types [R2ClAu(dppm)Au(PPh3)]ClO4 and [R3Au(dppm)Au(PPh3)]ClO4 or of neutral ones [R2ClAu(dppm)AuX] and [R3Au(dppm)AuX](R = C6F5, X = Cl or C6F5). Reaction of [AuClR2(dppm)] with AgClO4 gives [AuR2(dppm)]ClO4 which has been structurally identified by X-ray crystallography. The crystals are orthorhombic, space group Pnma, with a= 17.204(4), b= 20.053(4), c= 11.348(2)A, Z= 4, and R= 0.065 for 3 401 unique observed reflections. Oxidation of [XAu(dppm)AuX](X = Cl or C6F5) with [TlClR2] or TlCl3 leads to the cationic trinuclear complex [ClAu(dppm)Au(dppm)AuCl][AuClR3], whose crystal structure has also been determined : space group P, with a= 12.170(6), b= 14.448(8), c= 23.780(10)A, α= 101.29(5), β= 90.01 (4), γ= 93.68(4)°, Z= 2, and R= 0.085 for 4 891 unique observed reflections. The cation shows short Au ⋯ Au contacts (ca. 3.1 A).
22 citations
TL;DR: The synthesis of 4-chloro-1,2,3,5-dithiadiazolium chloride (9) from SCI2 and either N-cyanosulfur difluoride imide (8) or bis(trimethylsilyl) carbodiimide (12) is described in this article.
Abstract: Die Synthese von 4-Chlor-1,2,3,5-dithiadiazolium-chlorid (9) aus N-Cyanoschwefeldifluoridimid (8) bzw. aus Bis(trimethylsilyl)carbodiimid (12) und SCI2 wird beschrieben. Das zu 9 analoge Dibromid 13 entsteht aus 8 und S2Br2. Mit Hilfe von Silbersalzen, Sauren und Lewis-Sauren last sich das ionisch gebundene Chlor in 9 leicht austauschen unter Bildung von CICN2SA− (9a–d, A− = AsF, SbCl, ½SnCl, SO3F−). An dem Hexafluoroarsenat 9a wurde eine Kristallstrukturbestimmung durchgefuhrt.
4-Chloro-1,2,3,5-dithiadiazolium Salts
The synthesis of 4-chloro-1,2,3,5-dithiadiazolium chloride (9) from SCI2 and either N-cyanosulfur difluoride imide (8) or bis(trimethylsilyl)carbodiimide (12) is described. The analogous dibromide 13 is formed from S2Br2 and 8. The ionic chlorine in 9 may easily be exchanged with the help of silver salts, acids, and Lewis acids yielding ClCN2SA− (9a–d, A− = AsF, SbCl. ½SnCl, SO). The crystal structure of the hexafluoroarsenate 9a has been determined.
19 citations
TL;DR: In this article, the triruthenium dodecacarbonyl [Ru3(CO)12] reacts with nitrobenzene to give [Ru 3(CO]10(NPh)](3) and [Ru 2.5(C)2] in low yields, accompanied by formation of CO2.
Abstract: Triruthenium dodecacarbonyl [Ru3(CO)12] reacts with nitrobenzene to give [Ru3(CO)10(NPh)](3) and [Ru3(CO)9(NPh)2](4) in low yields, accompanied by formation of CO2. The solution i.r. spectrum of (3) suggests the presence of triply bridging NPh and CO groups, confirmed by a single-crystal X-ray structure determination; space group P21/n, a= 12.457(1), b= 11.428(1), c= 29.234(2)A, β= 92.38(1)°, Z= 8, and R= 0.036 for 4 817 unique observed reflections. The two independent molecules differ slightly in the relative orientations of the phenyl groups. Mean bond lengths include Ru–Ru 2.746(5), Ru–µ-C 2.172(8), and Ru–µ-N 2.055(5)A. The i.r. Spectra of complexes (3) and (4) are discussed in terms of a molecular-orbital description of ‘ M3(CO)9’ moieties.
19 citations
TL;DR: In this article, the synthesis and successful rearrangement of the pentaspirane 4 yields the hexacyclic 11, whose stereochemistry was unequivocally established as all- cis by X-ray analysis of a single epoxide derived therefrom.
18 citations
TL;DR: In this article, the compounds [(CH 2 X) 3 2 Ag]AsF 6 (X = S, Se) have been prepared from CH 2 X 3 and AgAsF6 in liquid So 2 as minor and major products respectively.
18 citations
TL;DR: In this article, the reaction of trimeric thioformaldehyde with AgAsF6 in liquid SO2 leads to the compound [Ag2{(CH2S)3}5][AsF 6]2·SO2, which was characterised by X-ray structure determination.
Abstract: The reaction of trimeric thioformaldehyde with AgAsF6 in liquid SO2 leads to the compound [Ag2{(CH2S)3}5][AsF6]2·SO2, which was characterised by X-ray structure determination [space group Pbca, with a= 16.286(3), b= 28.487(5), c= 18.118(3)A, and Z= 8; R= 0.061 for 5 150 unique observed reflections]. The isolated canons, of the form L2AgLAgL2(L = ligand), display irregular co-ordination geometry at silver; one silver is co-ordinated by four sulphurs from three ligands, the other by five sulphurs from three ligands.
17 citations
TL;DR: In this paper, the lithium salt of t-butylaminofluorobis(methyltrimethylsilylamino)silane, (Me3SiNMe)2SiFNLiCMe3, reacts with aluminium trichloride to form a dimeric silylaminodichloroalane, [(Me2SiNsMe) 2SiFNCMe3AlCl2]2 (I); the cyclodisilazane [(Me3 SiNMe),2SiNCMe 3]2,
TL;DR: In this paper, a planar Si2P2 ring with SiP bonds between 224.1 (1) and 228.0(1) pm was found for cyclic compounds 4 and 5.
Abstract: Lithiiertes tert-Butylphosphan reagiert mit Di-tert-butyldifluorsilan und Difluorbis[methyl(trimethylsilyl)amino]silan zu den (Fluorsilyl)phosphanen 1 und 2 sowie zum (Di-tert-butylsilandiyl)-bisphosphan 3. Die cyclischen Verbindungen 4 und 5 werden durch die Umsetzung von 1 und 2 mit tert-C4H9Li erhalten. Dilithiiertes 3 reagiert mit Dichlorphenylphosphan zum 1,2,3-Triphospha-4-silacyclobutan 6. Nach Kristallstrukturanalysen besitzen 4 und 5 jeweils planare Si2P2-Ringe mit SiP-Bindungen zwischen 224.1(1) und 228.0(1) pm.
Cyclisation of (Fluorsilyl)phosphanes to 1,3-Diphospha-2,4-disilacyclobutanes – Crystal Structure Determinations
Lithiated tert-butylphosphane reacts with di-tert-butyldifluorosilane and with difluorobis[methyl(trimethylsilyl)amino]silane to give the (fluorosilyl)phosphanes 1 and 2 as well as the (di-tert-butylsilanediyl)bisphosphane 3. The cyclic compounds 4 and 5 are obtained in the reaction of 1 and 2 with tert-C4H9Li. Dilithiated 3 reacts with dichlorophenylphosphane to form the 1,2,3-triphospha-4-silacyclobutane 6. According to crystal structure analyses, 4 and 5 contain planar Si2P2 rings with SiP bonds between 224.1(1) and 228.0(1) pm.
TL;DR: The structure of the γ-naphthocyclinone has been investigated in this paper, showing the configuration of the central bicyclo[3.2.1] octadienone ring to be 6′R, 8′S.
TL;DR: In this article, the crystal structure of [AuCl(C4Ph4)(phen)] has been determined : space group P, a= 11.040(2)°, b= 12.283(2), c= 13.670(3)A, α= 99.76(2).
Abstract: The reaction between [{AuCl(C4Ph4)}2](C4Ph4= 1,2,3,4-tetraphenylbuta-1,3-diene-1,4,diyl) or [AuCl(C4Ph4)(tht)] and neutral unidentate ligands L gives rise to bridge cleavage or to displacement of the tetrahydrothiophen ligand (tht) yielding neutral complexes of the type [AuCl(C4Ph4)L][L = pyridine, PPh3, P(C6H11)3, or CNBut]. The reaction of the dimeric complex with NEt4Cl leads to the anionic complex [NEt4][AuCl2(C4Ph4)]. The use of bidentate ligands allows the preparation of two different types of complexes : [Au(C4Ph4)(L–L)][AuCl2(C4Ph4)][L–L = 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), or Ph2P(CH2)2PPh2(dppe)] and [AuCl(C4Ph4)(L–L)][L–L = phen or 2,2′-biquinolyl (bquin)]. Preparations of the probably non-heterocyclic [Pd2Cl2(C4Ph4)(bipy)2] and two gold(I) complexes [Au2(C4Ph4)(PPh3)2] and [Au2(C4Ph4)(dppe)] are also described. The crystal structure of [AuCl(C4Ph4)(phen)] has been determined : space group P, a= 11.040(2), b= 12.283(2), c= 13.670(3)A, α= 99.76(2), β= 113.58(2), γ= 101.94(2)°, R= 0.030. Distorted five-co-ordination is observed [Au–N 2.184(4) and 2.755(4)A].
TL;DR: In this paper, the [(CH2O)6Ag2]2+ cation, which possesses approximate D3d symmetry with the two silver atoms each co-oriented by alternate oxygens of a novel twelve membered macrocyclic ether, was isolated from the reaction of (CH 2O)3 with AgAsF6.
Abstract: Crystals containing the [(CH2O)6Ag2]2+ cation, which possesses approximate D3d symmetry with the two silver atoms each co-oriented by alternate oxygens of a novel twelve membered macrocyclic ether, were isolated from the reaction of (CH2O)3 with AgAsF6.
TL;DR: The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 874 as discussed by the authors, and the full manuscript is available in: http://www.anie.org.
Abstract: The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 874. DOI:10.1002/anie.198308740
TL;DR: In this paper, the Au2(SeO2)2O was prepared from gold and excess selenic acid in a sealed tube at 533 K. The crystal structure [Pba2, a = 659.2(2), b = 1183.7(3), c = 399.8(1) pm, Z = 2,R = 0.087] was determined; gold atoms are bridged by oxide ions and selenite ions.
Abstract: Abstract Au2(SeO2)2O was prepared from gold and excess selenic acid in a sealed tube at 533 K. The crystal structure [Pba2, a = 659.2(2), b = 1183.7(3), c = 399.8(1) pm, Z = 2,R = 0.087] was determined; gold atoms are bridged by oxide ions (lying on twofold axes) and selenite ions. The extended structure consists of polymeric layers parallel to the xy-plane. The light atom positions are inaccurate because of the presence of a heavy atom in a polar space group.
TL;DR: In this paper, a triclinic, space group P, VNSNSN ring was refined to R= 0.053 for 1 601 unique observed diffractometer data.
Abstract: Tetrasulphur tetranitride reacts with excess of VCl4 in CH2Cl2to form a mixture of VCl2(S2N3)(2) and S2N2·VCl4(3), whereas with excess of TiCl4 only S4N4·TiCl4(1) is formed. Crystals of (2) are triclinic, space group P, with a= 571.3(2), b= 695.7(3), c= 772.9(3) pm, α= 95.38(3), β= 99.62(3), γ= 97.58(3)°, and Z= 2. The structure was refined to R= 0.053 for 1 601 unique observed diffractometer data. It consists of chlorine-bridged dimers, linked by additional weak V–N interactions to form polymeric chains. The six-membered VNSNSN ring is effectively planar.
TL;DR: In this article, a reaction de [MoOCl 3 (th 7 ) 2 ] avec les thiols aromatiques HSAr and le methoxyde de sodium/methanol conduit aux ions complexes [Mo 2 O 2 (SAr) 6 (OMe)] −.
Abstract: La reaction de [MoOCl 3 (th 7 ) 2 ] avec les thiols aromatiques HSAr et le methoxyde de sodium/methanol conduit aux ions complexes [Mo 2 O 2 (SAr) 6 (OMe)] − . Le complexe [Et 4 N] [Mo 2 O 2 (4-MeC 6 H 4 S) 6 (OMe)] cristallise dans le groupe P2 1 2 1 2 avec a=26,416, b=41,380 et c=15,237 A, Z=12. Affinement jusqu'a R=0,110
TL;DR: Dimeric pentafluoro-N-methylbenzimidoyl-bridged palladium(II) derivatives react with isonitriles to give monomeric, terminal imidoyal complexes, whereas PPh3 causes elimination of methyl isonitrile from the IMIDoyl group as mentioned in this paper.
TL;DR: In this article, the crystal structure determination of a five-membered ring cross dimer has been confirmed by the crystal analysis of cyclic silylhydrazine rings.
Abstract: N,N-Bis(fluorsilyl)amine (1 – 3) reagieren mit dilithiierten Hydrazinen zu vier- und funfgliedrigen Silylhydrazinringen (4 – 8). Praparativ gelang der Nachweis der Isomerisierung eines 3-(tert-Butylamino)-1,3-diaza-2,4-disilacyclobutans (8) zum 1,2,4-Triaza-3,5-disilacyclopentan (9). Lithiumsalze von Silylhydrazinen reagieren mit Fluorsilanen unter Substitution (10 – 15). Dilithiiertes Hydrazin reagiert mit Me2SiF2 zu N(SiFMe2)3 (16). Die Bildung von isomeren N-(Fluorsilyl)-N,N′-bis(trimethylsilyl)- und N′-Fluorsilyl-N,N-bis(trimethylsilyl)hydrazinen wird durch Ringschlusreaktionen (17 – 19) nachgewiesen und durch die Kristallstrukturuntersuchung eines Kreuz-Dimeren-Funfrings belegt (19). Der zehngliedrige Bicyclus 22 entsteht in der Reaktion des N,N′-Bis(fluordimethylsilyl)-N,N′-bis(trimethylsilyl)hydrazins(14) mit dilithiiertem Hydrazin.
Synthesis of Cyclic Silylhydrazines – Crystal Structure of a Five-membered Cross Dimerisation Product
N,N-Bis(fluorosilyl)amines (1 – 3) react with dilithiated hydrazines to give four- and five-membered silylhydrazine rings (4 – 8). The isomerisation of a 3-(tert-butylamino)-1,3-diaza-2,4-disilacyclobutane (8) to a 1,2,4-triaza-3,5-disilacyclopentane (9) has been demonstrated. Lithium salts of silylhydrazines react with fluorosilanes to give substitution products (10 – 15). Dilithiated hydrazine reacts with Me2SiF2 yielding N(SiFMe2)3 (16). The formation of isomeric N-(fluorosilyl)-N,N′-bis(trimethylsilyl)- and N′-(fluorosilyl)-N,N-bis(trimethylsilyl)hydrazines has been accomplished via ring-closure reactions (17 – 19) and confirmed by the crystal structure determination of a five-membered ring cross dimer (19). The ten-membered bicyclic ring system (22) is obtained by the reaction of (14) with dilithiated hydrazine.
TL;DR: The Titelverbindungen XNCFCFNX (13, 14, X = Cl, Br) lassen sich in einfacher Weise aus den drei Komponenten Dicyan, X2 and HgF2 gewinnen as mentioned in this paper.
Abstract: Die Titelverbindungen XNCFCFNX (13, 14, X = Cl, Br) lassen sich in einfacher Weise aus den drei Komponenten Dicyan, X2 und HgF2 gewinnen. Als weitere Produkte konnten die N-halogenierten Amino- bzw. Iminoperfluorethane Cl2NCF2CF2NCl2 (11), ClNCF-CF2NCl2 (12), BrNCFCF2NBr2 (15) und Br2NCF2CF2NBr2 (16) nachgewiesen werden. Aus Einkristall-Rontgenbeugungsdaten wurde die Struktur von 14 bestimmt.
TL;DR: In this paper, a triclinic complex of tetrasulphur tetranitrogen dioxide ligands has been prepared, which is known as [Ag(S4N4O2)4]+[AsF6].
Abstract: A complex of silver(I) containing tetrasulphur tetranitrogen dioxide ligands has been prepared. The crystals of [Ag(S4N4O2)4]+[AsF6]– are triclinic, space group P, with unit-cell dimensions a= 1 142.6(6), b= 1 194.9(5), c= 1 254.8(6) pm, α= 66.44(4), β= 96.71(4), γ= 91.30(4)°, and Z= 2, final R= 0.039 for 4 968 unique diffractometer data with F > 3σ(F). The Ag atom lies 53 pm below a square of four nitrogen atoms (mean Ag–N 256 pm). Bisdisphenoidal (triangulated dodecahedral) co-ordination of Ag is completed by two intramolecular Ag–O contacts (mean 307 pm), and intermolecular Ag–N and Ag–O interactions (both 273 pm). These intermolecular interactions give rise to a centrosymmetric cationic dimer. The S4N4O2 ligands are approximately planar except for the SO2 units; only nitrogen and oxygen atoms attached to SVI interact with Ag, thereby causing the least disruption of delocalised bonding in the rest of the ring.
TL;DR: In this paper, the reaction of 1,1-diphenylhydrazine with S2Cl2 in the presence of triethylamine leads to 1, 1-dimethylthionitrosamine, and the chromium pentacarbonyl derivative was isolated and characterised by X-ray structure determination.
Abstract: The reaction of 1,1-diphenylhydrazine with S2Cl2 in the presence of triethylamine leads to 1,1-diphenylthionitrosamine. The chromium pentacarbonyl derivative was isolated and characterised by X-ray structure determination; [Cr(SNNPh2)(CO)5](2) crystallises in the space group P21/c with a= 786.5(1), b= 2 236.5(2), c= 1 054.6(1) pm, β= 89.44(8)°, and Z= 4; [Cr(SNNMe2)(CO)5](3) also crystallises in P21/c, with a= 1 042.2(3), b= 1 250.7(4), c= 954.6(3) pm, β= 110.21(3)°, and Z= 4. The structures were refined to R= 0.079 for 1 573 diffractometer data with F > 3σ(F), and R= 0.049 for 2 388 data with F > 3σ(F) respectively. The structures are similar, with CrSNNC2 planes approximately eclipsed to the carbonyls. One of the phenyl groups in (2) can take part in π interaction with the nitrogen atoms, which is associated with longer N–N and shorter S–N and Cr–S bonds in (2) than in (3).
TL;DR: Das vollstandige Manuskript dieser Zuschrift as mentioned in this paper was published in 1983, 874, and it is available in Amazon.com for a limited time.
Abstract: Das vollstandige Manuskript dieser Zuschrift erscheint in: Angew. Chem. Suppl. 1983, 874. DOI: 10.1002/ange.198308740
TL;DR: In this article, the complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 945; DOI:10.1002/anie.198309450
Abstract: The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 945. DOI:10.1002/anie.198309450
TL;DR: In this paper, the title compound was isolated from the reaction of AgAsF6 with S(NSO)2 in liquid SO2, and it crystallises in the rhombohedral space group R3c, with a=b= 18.249(5), c= 35.95(2)A, and Z= 6.070.
Abstract: The title compound was isolated from the reaction of AgAsF6 with S(NSO)2 in liquid SO2. It crystallises in the rhombohedral space group R3c, with a=b= 18.249(5), c= 35.95(2)A, and Z= 6. The structure was refined to R= 0.070 for 1 653 unique observed diffractometer data. There are two crystallographically independent silver atoms. One lies on a three-fold axis and is octahedrally co-ordinated by the terminal oxygens of six S(NSO)2 ligands; the other occupies a general position and is unsymmetrically co-ordinated by the nitrogen atoms of three S(NSO)2 ligands. The ligands bridge the silver atoms to form a polymeric cationic network; the AsF6– anions and SO2 solvent molecule occupy holes in this network without themselves acting as ligands.
TL;DR: In this paper, the six membered ring of composition (CH3)2NCN3S2Cl2 3 a was prepared from N,N-dimethylguanidinhydrochloride and trithiadiazindichloride.
Abstract: Abstract The six membered ring of composition (CH3)2NCN3S2Cl2 3 a was prepared from N,N-dimethylguanidinhydrochloride and trithiadiazindichloride. 3 a was characterized on the basis of mass, 1H, 13C NMR spectra and X-ray structure analysis. Crystals of 3 a are monoclinic, space group P21/c, with a = 660.3(6), b = 834.5(7), c = 1774.7(15) pm, β = 112.83(6)° and Z = 4. The C2N unit lies approximately in the plane of the [-CNSNSN-] ring, with both Cl atoms on the same side of the ring.
TL;DR: In this article, the existence of a silaolefin and crystal structures of Wittig and Diels-Alder products in Reactions of Lithiated (Fluorosilyl)diazasilacyclopentenes with benzaldehyde and Methacrolein are discussed.
Abstract: Lithiumsalze der 1,2-Diaza-3-sila-5-cyclopentene reagieren mit Fluorsilanen und Aminofluorsilanen zu den 4-(Fluorsilyl)-substituierten Verbindungen 1 – 4. In Reaktion mit tert-Butyllithium bilden 1 – 4 erneut Lithiumsalze (5 – 8), die mit Fluorsilanen unter Zweitsubstitution zu 9 und 10 reagieren. In Wittig-analoger Reaktion reagieren 5 und 7 mit Benzaldehyd zum Benzyliden-Derivat 11. Spirocyclische Diels-Alder-Addukte (12, 13) werden aus 5 und 6 mit 2-Methyl-2-propenal erhalten. Als Nebenprodukt entsteht das Propenyliden-Derivat 14. Mit uberschussigem Dien (2-Methyl-2-propenal) reagiert 12 als Dienophil zu den oligocyclischen Diels-Alder-Addukten 15 und 16. Kristallstrukturen von 11 und 15 werden mitgeteilt.
On the Existence of a Silaolefin: Synthesis and Crystal Structures of Wittig and Diels-Alder Products in Reactions of Lithiated (Fluorosilyl)diazasilacyclopentenes with Benzaldehyde and Methacrolein
Lithium salts of 1,2-diaza-3-sila-5-cyclopentenes react with fluorosilanes and aminofluorosilanes to give 4-(fluorosilyl)-substituted compounds 1 – 4. By reaction with tert-butyllithium 1 – 4 themselves form lithium salts 5 – 8, which react with fluorosilanes in a second substitution giving 9 and 10.5 and 7 undergo a Wittig-type reaction with benzaldehyde to form the benzylidene derivative 11. Spirocyclic Diels-Alder adducts (12, 13) are obtained from the reaction of 5 and 6 with 2-methyl-2-propenal. The propenylidene derivative 14 is formed as a by product. With excess 2-methyl-2-propenal, 12 reacts as a dienophile giving the oligocyclic Diels-Alder adducts 15 and 16. The crystal structures of 11 and 15 are reported.