Organoborierung von Alkinylstannanen, XVIII. Neue kondensierte heterocyclische Systeme aus N- und C-lithiierten Azolen und cis- 1,2-organometallisch substituierten Alkenen/ Organoboration of Alkynylstannanes, XVIII. Novel Fused Heterocyclic Systems from N- and C-Lithiated Azoles and cis-1,2-Organometallic Substituted Alkenes

Kerschl, Susanna; Wrackmeyer, Bernd

doi:10.1515/znb-1986-0716

Zeitschrift Für Naturforschung B

1986

DOI: 10.1515/znb-1986-0716

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Organoborierung von Alkinylstannanen, XVIII. Neue kondensierte heterocyclische Systeme aus N- und C-lithiierten Azolen und cis- 1,2-organometallisch substituierten Alkenen/ Organoboration of Alkynylstannanes, XVIII. Novel Fused Heterocyclic Systems from N- and C-Lithiated Azoles and cis-1,2-Organometallic Substituted Alkenes

Susanna Kerschl¹,

Bernd Wrackmeyer²

Abstract: AbstractOrganoboration of dimethyl(chloro)-1-propynylstannane with triethylborane gives (E̲)-2-dimethyl(chloro)stannyl-3-diethylboryl-pent-2-ene (2a) in high yield. Reactions of 2a with N- and C-lithiated azoles (pyrazole, 1-m ethylimidazole, 1-methyl-1,2,4-triazole) lead to the new fused heterocyclic systems 8, 10, 12. In the case of 10 and 12 it was possible to detect (by 11B, 119Sn NM R ) the isomers 9 and 11 which have a zwitterioni… Show more

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Cited by 16 publications

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Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ⁴‐sulfanyliden)‐1,2,5‐azastannaboratolen

et al. 1991

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from the boron to the sulfur atom. Ethylene is eliminated from compound 6a (not 6b) to give the diaminosulfane derivative 7a. The 2: 1 reaction between 1 and 4 affords an unstable intermediate 8 with a fluxional structure, leading to 9 in which an EtS moiety bridges a borole ring (analogous to 6 but without the additional N -Sn coordination) and a boratole ring (analogous to 5). All compounds are characterized by 'H-, "B-, I3C-, "N-(in part), "Si-and "'Sn-NMR spectra.Organometallische Substituenten an der C = C-Doppelbindung nehmen groDen Einflulj auf die Reaktivitlt von Alkenen. Bei cis-Stellung der Substituenten sind neuartige Reaktionen entweder an den metallischen Zentren und/oder an der C = C-Doppelbindung moglich. So verleiht die Anwesenheit zweier elektrophiler Gruppen an der C = C-Doppelbindung in 1 diesem Alken-Derivat bemerkenswerte Eigenschaften in Reaktionen rnit Nucleophilen'). Bisher haben wir zahlreiche Umsetzungen von 1 mit Agentien untersucht, die entweder uber ein nucleophiles Zentrum (z.B. Metallamide 233J) oder iiber zwei benachbarte nucleophile Zentren Ergebnisse und Diskussion Praparative BefundeFuhrt man die Umsetzungen von 1 mit 3 bei 0°C in Hexan durch, lassen sich die Produkte 5a,b bei -30°C als kristalline orangegelbe Feststoffe isolieren; 5c bildet tiefrote Kristalle. Die Struktur dieser Verbindungen folgt schlussig aus den NMR-Daten in Losung und wird durch die Ergebnisse der Rontgenstrukturanalysen bestiitigt. Bei Raumtemperatur in Losung lagern sich 5a,b allmlhlich in 6a,b um, wobei eine Ethylgruppe vom Bor-zum Schwefel-Atom ubertragen wird (Gl. 2). Das Bor-Atom ist in 6 wieder trigonalplanar umgeben, wahrend fur das Zinn-Atom aufgrund der NMR-Daten die Koordinationszahl 5 anzunehmen ist.Fur R = tBu folgt der Umlagerung zu 6a, ebenfalls bereits bei Raumtemperatur, die Eliminierung von Ethylen, Chem. Ber. 124 (1991)

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Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ⁴‐sulfanyliden)‐1,2,5‐azastannaboratolen

et al. 1991

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2,5‐Dihydro‐1,2,5‐azoniasilaboratole Derivatives – Useful Starting Materials in Heterocyclic Synthesis

1996

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1-Alkynyl(diethy1amino)dimethylsilanes [C=CR: R = Me (la), nBu (lb), SiMe, ( l c ) ] react with triethylborane stereoselectively by 1,l-ethyloboration to give the alkenes with the boryl and silyl group in cis-positions at the C=C bond. Owing to the strongly intramolecular coordinative N-B bond, these products are 2,5-dihydro-1,2,5-azoniasilaboratoles (2a-c). Protic reagents such as azoles (indole, pyrazole, imidazole, triazole, indazole, benzotriazole) react with 2 to give diethylamine and the respective N-azolyl derivatives 3-8 which contain tetracoordinate boron in the case of 4-8. Compound 7, derived from indazole, was characterized by an X-ray analysis. With ethanol, the corresponding 2,5-dihydro-1,2,5-oxoniasilaboratoles 9 are obtained. Treatment of 2 with water affords 1,2,5-oxasilaborolanes 11, presumably via an intermediate 10 with the structure of a 2,5-dihydro-1,2,5-oxoniasilaboratole. All products were characterized by their 'H-, '*B-, 13C-, 15N-, and 2gSi-NMR data.Heterocycles containing reactive silicon-and boron-element bonds are of considerable interest for further synthetic use. In organotin chemistry, 1,1-organoboration of 1 -alkynyltin compounds proved to be extremely useful in heterocyclic syntheses"], whereas similar strategies in organosilicon chemistry have so far been demonstrated only for four types of heterocyclic systems, namely 1,2-dihydro-1,2,5-disilaborepine~[~], ~iloles[~-~], 1,l '-spirobisiloles[61, and recently for the synthesis of heterobicyclic boron com-pound~[~].The synthesis of 2,5-dihydro-l,2,5-azoniasilaboratoles of the type 2 was described previously by the route shown in eq. (1)[31. In this paper we report on a more direct way [eq.(3)], using 1,1 -organoboration, by starting from l-alkynyl-(diethy1amino)dimethylsilanes 1 and triethylborane, Et3B. The compounds 1 were prepared in high yield according to eq. (2), whereas in the literature differing routes such as the aminolysis of 1 -alkynylchlorodimethylsilanes[sl or 1 -alkynyl(trifluorosulfonato)dimethylsilane[9] are described.The synthetic potential of the heterocycles 2 was tested in reactions with some protic reagents such as various azoles, ethanol, and water. Results and Discussion Preparative ResultsThe 1-alkynyl(diethy1amino)dimethylsilanes 1 are colorless liquids, easy to purify by distillation, but sensitive to moisture. In contrast to the corresponding tin comthey are not in equilibrium with the symmetrically substituted silanes, even at a temperature of + HCI J(c)-NaCl I i a i b i : R Me "Bu SiMe, ,NEt2 ENf2 + Et,B I_) Me2SI(;BEt, (3) \ Me,Si RnEt \ \ \R 2 a, b, c I a, b, c 100-126°C. The reaction of 1 with Et,B proceeds slowly (several days) at 100°C, either in pure Et3B or in toluene, and gives the compounds 2 in high yield [eq. (3)].The 2,5-dihydro-l,2,5-azoniasilaboratoles 2 are colorless liquids and can be distilled at reduced pressure. They are sensitive to traces of moisture, but can be stored for several

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1,1-organoboration of alkynylsilicon, -germanium, -tin and -lead compounds

Wrackmeyer

1995

Coordination Chemistry Reviews

133

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Cited by 16 publications

References 3 publications

Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ⁴‐sulfanyliden)‐1,2,5‐azastannaboratolen

Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ⁴‐sulfanyliden)‐1,2,5‐azastannaboratolen

2,5‐Dihydro‐1,2,5‐azoniasilaboratole Derivatives – Useful Starting Materials in Heterocyclic Synthesis

1,1-organoboration of alkynylsilicon, -germanium, -tin and -lead compounds

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Cited by 16 publications

References 3 publications

Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ4‐sulfanyliden)‐1,2,5‐azastannaboratolen

Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ4‐sulfanyliden)‐1,2,5‐azastannaboratolen

2,5‐Dihydro‐1,2,5‐azoniasilaboratole Derivatives – Useful Starting Materials in Heterocyclic Synthesis

1,1-organoboration of alkynylsilicon, -germanium, -tin and -lead compounds

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Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ⁴‐sulfanyliden)‐1,2,5‐azastannaboratolen

Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ⁴‐sulfanyliden)‐1,2,5‐azastannaboratolen