Über die Reduktion des Benzvalenozonids zum cis ‐1,3‐Cyclobutandimethanol mit LiAlH ₄

Abstract

Das polymere Ozonid des Benzvalens (1) wird mit LiAlH4 bei −30°C in Bicyclo[1.1.0]butan‐endo,endo‐2,4‐dimethanol (7) übergeführt, bei höherer Temperatur entsteht cis‐1,3‐Cyclobutan‐dimethanol (4). Mit deuterierten Verbindungen wurde der stereochemische Ablauf dieser ungewöhnlichen CC‐Hydrogenolyse aufgeklärt. Dazu mußte eine vollständige Analyse der 1H‐NMR‐Spektren der markierten cis‐1,3‐Cyclobutandicarbonsäureanhydride 9a–c durchgeführt werden. 7 und sein Bismethylether 16 addieren an der zentralen Bindung Thiophenol zu den cis‐Produkten 18 bzw. 19. Säure oder Ag+‐Ionen überführen 7 unter Öffnung einer seitlichen Bindung in die Ether 21.

endo,endo‐2,4‐Bis(azidomethyl)bicyclo[1.1.0]butane: A Highly Strained Organic Diazide

“…In particular, diazide 9 was easily prepared by using QN 3 as the nucleophile. Finally, it is pointed out that 1 is synthesized from benzvalene in three simple steps, [18,25] and that benzvalene is accessible in preparatively useful amounts from cyclopentadiene in a one-pot procedure. In addition, such a compound would offer the opportunity for further derivatization because of the high strain energy of the bicyclo[1.1.0]butane system.…”

endo,endo- andexo,exo-Bicyclo[1.1.0]butane-2,4-dimethanol Dimesylate: Synthesis, Structure and Solvolysis

“…Crude endo,endo-9 (1.72 g) was obtained from the dialcohol endo,endo-8 (1.00 g), according to the procedure described previously. [6] At variance with the earlier experiment, it turned out to be a yellowish solid. Dissolution in CH 2 Cl 2 /light petroleum ether (referring to the fraction with b.p.…”

“…[6] Benzvalene [7] was ozonised and the ozonide reduced to give bicyclobutane-2,4-dimethanol endo,endo-8, which was converted into endo,endo-9 under standard conditions (Scheme 3). Unlike in the earlier investigation, [6] endo,endo-9 was this time obtained as a pure crystalline solid in 57% yield. According to the X-ray structure analysis (Figure 1), endo,endo-9 possesses C 2 symmetry in the crystal.…”

“…Structural assignments of all new compounds were based on known NMR parameters of model compounds, namely those of 15a [14] for the bicyclobutane derivatives (exo,exo-8, exo,exo-9, exo,exo-15b, 25), those of 22 [6] for the disubstituted cyclobutanes (23,24), and those of (1α,2α,3α)-2-(phenylsulfanyl)cyclobutane-1,3-dimethanol [6] for the trisubstituted cyclobutanes (18,20,21). The parent bicyclobutane shows highly characteristic one-bond 13 …”

“…Since mesylates and tosylates solvolyse approximately equally rapidly, [3] we chose to study the ditosylate 28. Of the known routes to this compound, [19Ϫ21] its synthesis from benzvalene (Scheme 10) [6,21] proved to be the most convenient one for us. When heated at 80°C in anhydrous ethanol in the presence of triethylamine, 28 was consumed completely within seven days and gave a mixture of rather volatile products, probably as the result of elimination reactions.…”