Toward a general route to the eunicellin diterpenes: the asymmetric total synthesis of deacetoxyalcyonin acetate

A novel approach to the hydroisobenzofuran core utilizing a TiCl4-mediated [4+3] annulation is reported. This [4+3] annulation protocol provides a short, general route to the hydroisobenzofuran core present in the eunicellin diterpenes. Using this annulation, a short synthesis (17 steps) of deacetoxyalcyonin acetate, a member of the eunicellin family, has been achieved.     

Michael additions to trifluoromethylvinyl sulfone

Michael addition reactions of trifluoromethyl vinyl sulfone with organic compounds with labile hydrogen atoms are studied. Such additions can be successfully accomplished using potassium fluoride and 18-crown-6-ether or benzyltrimethylammonium hydroxide (Triton B) as catalysts.     

Identification and decay of182Tl

A new activity with a 3s half-life at mass 182 was produced via proton spoliation reaction on thorium carbide target and mass separation. From the observation of known rays observed in¹⁸²Hg, it was assigned to the (⁺+ EC) decay of¹⁸²Tl, the spin and parity of which is very likely 7⁺.     

Darstellung und charakterisierung von trifluormethylthio-cyclopropanen

The reactions of dihalogenocarbenes (CX₂, X = F, Cl, Br) with CF₃SCHCH₂ or (CF₃S)₂CCH₂ yield the corresponding substituted cyclopropanes. 1,1-Dibromo-2-trifluoromethylthio- or 1,1-dibromo- 2,2-bis(trifluoromethylthio)cyclopropanes react with (nC₄H₉)₃SnH to form trifluoromethylthio - or 1,1-bis(trifluoromethylthio)cyclopropane in good yields. Physical and spectroscopic data of the new substances are provided.     

Aminoalkoholester von Hydroxyboranen,IX Salicylamid-Bor-Mannichbasen als potentielle Antitumorwirkstoffe

A synthesis of new boron containingMannich bases of salicylamide by reaction of salicylamide, formaldehyde and boron-heterocycles is reported.

VIII. Mitteilung:Stump, R. K., Zimmerman jr., H. K., Schleppnik, A. A., Gutsche, C. D., Liebigs Ann. Chem.667, 18 (1963).     

Ergebnisse aus versuchen zur darstellung von bis(trifluormethylsulphanyl)thioketen (CF3S)2C=C=S

The attempted preparation of bis(trifluoromethylsulphanyl)thioketene is described. Mono-and di-(trifluoromethylsulphanyl)-substituted orthothioesters may be prepared fromCH₃C(SC₂H₅)₃ and CF₃SCl in the presence of anhydrous ZnCl₂. The unstable compoundshave been isolated and characterized. The corresponding CF₃Se and CF₃SO₂ derivativesare only formed as intermediates which decompose to ketene diethylmercaptal. Suchmono- and di-substituted products are obtained in good yield from H₂C=C(SC₂H₅)₂ andCF₃ECl (E=S, Se). The reaction of H₂C=C(SC₂H₅)₂ with CF₃SO₂F gave only poor yieldsof (CF₃SO₂)_nCH_2−n=C(SC₂H₅)₂ (n=1, 2) which were only capable of characterizationin etheral solution by spectral means. Attempts to prepare (CF₃S)₂C=C=S by refluxing(CF₃S)₂CHC(O)Cl, (CF₃S)₂CHC(O)OH or (CF₃S)₂C=C=O with P₄S₁₀ in toluene yieldedonly the cyclic dimer and the corresponding 1,3,4-trithiolan.     

Darstellung und Reaktionen von Selenocarbonyldifluorid und seines cyclischen Dimeren 2,2,4,4-Tetrafluor-1,3-diselenetan [l]

Inhaltsübersicht. Das erstmals hergestellte B(SeCF₃)₃ zerfällt unter dem katalytischen Einfluß von Alkalifluoriden zu F₂C=Se und BF₃. In Anwesenheit von BF₃ polymerisiert F₂CSe bereits. bei ?;80°C. Oberhalb 150°C depolymerisiert (F₂CSe)_n wieder zu F₂C=Se und. Durch Halogenaddition an F₂C = Se gewinnt man F₂XCSeX (X = Cl, Br). Das in der Reihe Cl_3–nF_nCSeCl noch fehlende Cl₂FCSeCl wird durch Umsetzung von CSe₂, ClF und Cl₂ synthetisiert. F_nCl_3–nCSeCl (n = 1. 2) liefert mit Zinn die entsprechenden symmetrischen Diselane, mit AgCN die Selenocyanate. Durch Halogenaustausch mit BX₃ (X = Cl, Br) wird umgewandelt. XC(S)Cl reagiert mit Hg(SeCF₃)₂ zu CF₃SeC(S)X (X = F, Cl. CF₃Se). Daraus werden durch Chloraddition die entsprechenden Sulfenylchloride synthetisiert. IR-NMR- und Massenspektren der neu hergestellten Substanzen werden angegeben. Preparation and Reactions of SeCF₂ and its Cyclic Dimer 2,2,4,4-Tetrafluoro-1,3-diselenetane Abstract. B(SeCF₃)₃, prepared for the first time, decomposes under the influence of alkali metal fluorides to F₂C=Se and BF₃. In presence of BF₃, SeCF₂ polymerizes even at ?80°C. Above 150°C (F₂CSe)n depolymerizes to F₂C = Se and Halogen addition to F₂C=Se produces F₂XCSeX (X = Cl, Br). The compound Cl₂FCSeCl could be synthesized by the reaction of CSe₂ with ClF and Cl₂. These selenenylchlorides react with tin producing the corresponding symmetric diselenides whereas with AgCN the selenocyanates are formed. can be transformed to through halogen exchange reaction with BX₃ (X = Cl, Br). XC(S)Cl reacts with Hg(SeCF₃)₂ to give CF₃SeC(S)X (X = F, Cl. CF₃Se), from which the corresponding sulfenylchlorides can be synthesized by chlorine addition. I.r., n.m.r., and mass spectra of the newly prepared compounds are reported.