Thermische stabilität von Bis(alk-2-enyl)zink-Verbindungen

The dialk-2-enylzinc compounds I–III react slowly at 20 to 50°C by addition of the ZnC bond to the CC bond of an alk-2-enyl group to give oligomers from which the alkenes XIII–XV are released on hydrolysis. For I–III homolytic cleavage of the ZnC_allyl bond, followed by coupling of the allyl radicals to give the alkadienes V–VII, IX and XI predominates above 50°C. IV decomposes mainly homolytically even at 20°C.     

Synthesis of indolines and tetrahydroquinolines fromortho-(alk-2-enyl)anilines

Intramolecular cyclization ofo-alkenylanilines was studied. Heating ofo-(cyclopent-2-en-1-yl) arylammonium chlorides at 200–220 °C yields cyclopenta[b]indolines as the main reaction products. Cyclization of 4-methyl-2-(pent-3-en-2-yl)aniline under the same conditions gave a mixture of indolines and tetrahydroquinolines. An alk-1-enylarylamine containing a vinylic double bond does not form cyclization products on the nitrogen atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 975–978, May, 1999.     

Cyclization of ortho-(alk-2-enyl)anilines under the action of iodine

The reaction of ortho-(cyclohex-2-enyl)aniline with I₂ in nonpolar and polar solvents affords predominantly 1-iodohexahydrocarbazole and azatricyclotridecatriene, respectively. Under analogous conditions, 4-methyl-2-(1-methylbut-2-en-1-yl)aniline undergoes cyclization to form exclusively products with quinoline structures regardless of the solvent used.     

Ortho-Formylierung von Anilinen durch Umlagerung von Bis(methylthio)methan-S-(N-aryl)imiden

By reaction of anilines with dithioacetals of formaldehyde [in particular, with bis(methylthio)methane] andtert. butylhypochlorite the corresponding intermediate mono-sulfimides are formed which rearrange easily—after addition of triethylamine—to yield dithioacetals5 ofo-amino benzaldehydes.

Herrn emer. o. Univ. Prof. Dr.O. Hromatka zum 80. Geburtstag gewidmet.     

Stereoselektive c-glycosidsynthese durch titan-(iv)-katalysierte addition von silylenolethern an 2-acyloxy-3-keto-glycale

C-Glycosides are stereoselectively formed by the titan-(IV)-catalysed addition of silyl enolethers $\text{2}$ to 2,4,6-tri-O-acyl-1-deoxy-D-erythro-hex-1-enopyran-3-uloses $\text{1}$ followed by elimination of the 4-acyloxy substituent. Cyclohexenyl silylether $\text{2a}$ reacts with 2-acetoxy-3-keto-glycal derivative $\text{la}$ forming only one product $\text{3a}$. Thus, the reaction seems to be diastereospecific with respect to both new chiral centers of the product.     

Darstellung von Cyclotrisilazanen durch Kondensation von Bis (alkylamino) silanen mit 1,3-Dichlordisilazanen

The title reaction (compare equ. 1) leads with yields of about 40% to the so far unknown compounds I to VI with various substituents on the N atoms in positions 2/4- and in 6. Some physical data are recorded in Table 1.     

A facile method for the synthesis of 3,1-benzooxazines from N-acyl-2-(alk-2-enyl)anilines

Electrophilic addition of HCl or Br₂ to N-acyl-2-(alk-2-enyl)anilines is accompanied by intramolecular cyclization of these amides to give 3,1-benzooxazine hydrochlorides or hydrobromides in high yields.     

Synthesis of 3,1-Benzoxazines from N-Substituted ortho-(Cycloalk-1-enyl or alk-2-en-2-yl)anilines

New derivatives of 3,1-benzoxazine have been synthesized by the cyclization of RCO-substituted at the nitrogen atom (R = OEt, Me, NH₂) ortho-(cycloalk-1-enyl or alken-1-yl)anilines under mild conditions.     

1-(1-Carboxy-2-R-4-methylcyclohex-4-enyl)carbonyl- and 1-(2-R-4-Methylcyclohex-4-enyl)carbonyl-3,5-dimethyl(diphenyl)pyrazoles

1-(1-Carboxy-2-R-4-methylcyclohex-4-enyl)carbonyl- and 1-(2-R-4-methylcyclohex-4-enyl)carbonyl-3,5-dimethyl(diphenyl)pyrazoles have been obtained from the reaction of monohydrazides of 2-R-methyl-4-cyclohexen-1,1-dicarboxylic acids and hydrazides of 2-R-4-methyl-4-cyclohexen-1-monocarboxylic acids with acetylacetone and dibenzoylmethane. The conditions for the formation of the pyrazoles depend on the nature of the substituents in the hydrazide starting materials and the structure of the 1,3-diketone used.     

Diacyltelluride: Synthesen durch Reaktionen von Acylchloriden mit Bis(trialkylsilyl)telluriden; Strukturbestimmungen an Di(1-adamantoyl)tellurid und Adamantancarbonsäureanhydrid

Diacyltellurides: Synthesis by Reactions of Acyl Chlorides with Bis(trialkylsilyl)tellurides. Structure Determinations of Di(1-adamantoyl)telluride and Adamantanecarbonic Anhydride Bis(isopropyldimethylsilyl)telluride ( 1 ) is prepared from tellurium with lithiumtriethylhydridoborate and chloro(isopropyl)dimethylsilane. From reactions of acylchlorides RCOCl with 1 , diacyltellurides (RCO)₂Te (R = CH₃- 2 , i-C₃H₇- 3 , i-C₄H₉- 4 , (CH₃)₃CH₂-) 5 are isolated in pure state after removal of chloro(isopropyl)dimethylsilane. With succinic and glutaric dichlorides, 1 leads to impure cyclic diacyltellurides 6 (tellurosuccinic anhydride) and 7 (telluroglutaric anhydride). The reactions of bulky pivaloyl chloride and 1-adamantoyl chloride with 1 are too slow to be synthetically useful, but using bis(trimethylsilyl)telluride, dipivaloyltelluride 8 and di(1-adamantoyl)telluride 9 are straightforwardly available. 9 is accompanied by traces of 1-adamantanecarbonic anhydride 10 and by small amounts of di(1-adamantyl)ditelluride 11 . Constitutions of the new compounds 1 , 3–7 and 9 were confirmed by multinuclear NMR and mass spectroscopy. The structures of 9 and 10 were determined by X-ray crystallography.     

Butatrien durch Thermolyse von Propiolsäure-(2-propinyl)ester

Flow thermolysis of 2-propynyl propiolate (5) at 580° afforded butatriene (6) (ca. 50%) and, as by-products, 4-methylene-2-cyclobuten-1-one (7) , 2-ethynylpropenal (8) , 1-penten-4-yn-3-one (9) , 4-penten-2-ynal (10) (total ca. 10%), along with some propynal, acetylene, CO₂ and CO. In the same way, propiolic acid (1,1-D₂)-2-propynyl propiolate (11) led to (1,1-D₂)-butatriene (12) and a little 4-((D₂)methylene)-2-cyclobuten-1-one (13). A mechanism is proposed for the transformation of 5 into 6 and of 11 into 12 , which also accounts for the formation of 7,8,9 and 10 , as well as 13. The position of one of the published ¹³C-NMR signals of butatriene (6) must be revised. Thermolysis of methyl- (1) and ethyl propiolate (2) resulted in small yields of 2-buten-4-olide (3) and 2-penten-4-olide (4).