Azimine. VI. 1-Alkoxycarbony 1-2,3-dialkyl- und -2,3-diaryl-azimine

Azimines VI: 1-Alkoxycarbonyl-2,3-dialkyl- and -2,3-diarylazimines Alkoxycarbonyl-nitrenes 2 – generated in situ by α-elimination from N-[(4-nitrophenyl)-sulfonyloxy]carbamates 4 – were reacted with six aliphatic and aromatic azo compounds to yield 1-alkoxycarbonyl-azimines 11 (R′ = Alkyl). Thus, (2Z)- or (2E)- 1 -alkoxycarbonyl-2,3-diisopropyl-azimines ( 8 or 9 ) were obtained stereospecifically from (E)- or (Z)-1,1′-dimethylazoethane ( 5 or 6 ) and 1-alkoxycarbonyl -2,3-(cis-1,3-cyclopentylene)-azimines ( 10 ) resulted from 2,3-diazabicyclo[2.2.1]-2-heptene ( 7 ), always using both ethoxy- and methoxycarbonyl-nitrene ( 2a and 2b ). With 2a , (E)-azobenzene ( 14 ) was converted only to a single stereoisomer of 1-ethoxycarbonyl-2,3-diphenyl-azimine ( 17 ) and both stereoisomers of azo(p-toluene) ( 15 or 16 ) reacted to give the same stereoisomer of 1-ethoxycarbonyl-2,3-di(p-tolyl)-azimine ( 18 ).     

Acyl- und Alkylidenphosphane. XVI. (Dimethylaminomethyliden)- und (Diphenylmethyliden)phosphane

Acyl- and Alkylidenephosphines. XVI. (Dimethylaminomethylidene)- and (Diphenylmethylidene) phosphines Alkyl- or arylbis(trimethylsilyl)phosphines 1 (R = mesityl, C₉H₁₁ a ; (CH₃)₃C b ; C₆H₅ c ; CH₃ d ) react only very slowly with dimethylformamide 2 and benzophenone 4. After repeated addition of small amounts of solid sodium hydroxide, however, the reaction-time is shortened from several months to a few days. The reactions between 1 a or 1 b and 2 yield the (dimethylaminomethylidene)phosphines 3 a and 3 b ; from 1 a and 4 mesityl-(diphenylmethylidene)phosphine 5 a is obtained. The formation of the thermally labile phosphines 3 d and 5 c is proved by NMR spectroscopy; these compounds dimerize very fast to give 2,4-bis(dimethylamino)-1,3-dimethyl- 10 d and 1,2,2,3,4, 4-hexaphenyl-1,3-diphosphetane 15 c. Similarly the lithium trimethylsilylphosphides 6 a , 6 c and 6 e (R = (CH₃)₃Si) react with 2 or 4 to form 3 a and 5 c as well as (diphenylmethylidene)-trimethyl-silylphosphine 5 e .     

Acyl- und Alkylidenarsane. VII. Tetrakis(2,2-dimethylpropionyl)diarsan - Darstellung und struktur

Acyl- and Alkylidenearsines VII Synthesis and Structure of Tetrakis(2,2-dimethylpropionyl)diarsine Lithium dihydrogenarsenide and 2,2-dimethylpropionyl chloride in a molar ratio of 3:2 react at ?40 to ?50°C in tetrahydrofuran or 1,2-dimethoxyethane to give the corresponding etherate of lithium bis(2,2-dimethylpropionyl)arsenide ( 2a ). Treatment of these solutions with stoichiometric amounts of 85% tetrafluoroboric acid · diethylether adduct yields yelloworange tetrakis(2,2-dimethylpropionyl)diarsine ( 5 ) in 64 or 62% yield resp., but not the expected bis (2,2-dimethylpropionyl)arsine ( 4a ). The very air-sensitive compound crystallizes in the monoclinic space group P2₁/n {?100 ± 3° C; a = 1224.6(3); b = 1419.7(3); c = 1333.1(3) pm; β = 96.22(2)°; Z = 4}. According to the X-ray structure analysis (R_w = 0.036) the molecule shows synclinal conformation; the two diacylarsyl-subunits are twisted against one another by an angle of 86°. As in another acylarsine [1] the As? C distances (203 to 205 pm) were found to be significantly longer then the standard value of 196 pm. Further characteristic bond lengths and angles are: As– 242; C? O 120 to 121 pm; As? As? C 88 to 107°; As? C? O 118 to 122°     

C45- und C50-Carotinoide. 5. Mitteilung

C₄₅- and C₅₀-Carotenoids. Synthesis of an Optically Active Cyclic C₂₀-Building Block and of (2R,2′S)-3′,4′-Didehydro-1′,2′-dihydro-2-(4-hydroxy-3-methylbut-2-enyl)-2′-(3-methylbut-2-enyl)-β,ψ-caroten-1′-ol (= C. p. 473) The synthesis of the optically active C₂₀-building block (R)- 16 and of the optically active C₅₀-carotenoid C.p. 473 ( 1 ) starting from (?)-β-pinene is reported.     

Bildung und Eigenschaften von Acylphosphanen. VI. Synthese von Alkyl- und Arylbis (trimethylsilyl)- sowie Alkyl und Aryltrimethylsilyphosphanen

Syntheses and properties of Acylphyosphanes. VI. Syntheses of Alkyl- or Arylbis (trimethylsilyl)- and Alkyl- or Aryltrimethylisilyphosphanes Methods for the preparation of alkyl-or arylbis (trimethylsily)-and alkyl-or aryltrimethylsilyphosphanes are described.

• 1 Primary phosphanes used for the syntheses of the title compounds were prepared by known methods (reduction with LiAlH₄).
• 2 Alkyl- and arylbis(trimethylsily) phosphanes are obtained from the corresponding dilithium phosphides (primary phosphanes and methyllithium) and trimethylchlorosilane or from lithiumbis (trimethylsilyl) phosphide and alkyl halides.
• 3 Suitable syntheses for alkyl-or aryltrimethylsilylphosphanes are the reactions of alkyl-and aryllithiumphosphides with trimethylchlorosilane or of alkyl- and arylbis (trimethylsily) phosphanes with methanole. The reaction between phenylbis (trimethylsilyl)phosphane and water was studied in detail and the formation of trimethylsilanole was proved by ¹H-n.m.r. spectroscopy.

The reactions of lithiumtrimethylsilyphosphides and 2,2-dimethylpropionyl chloride yield (2,2- dimethylpropionyl) trimethylsilylphosphanes (keto forms).     

Acyl- und Alkylidenphosphane. XXVIII. Synthese und Struktur von 1,3-Dibenzyl- und 1,3-Diethyl-2,4-bis(phenylimino)-1,3-diphosphetan

Acyl- and Alkylidenephosphines. XXVIII. Synthesis and Structure of 1,3-Dibenzyl- and 1,3-Diethyl-2,4-bis(phenylimino)-1,3-diphosphetane Catalyzed by small amounts of solid sodium hydroxide, the adducts 1a and 1b formed from benzyl- or ethylbis(trimethylsilyl)phosphine and phenylisocyanate, react at +20°C slowly to give hexamethldisiloxane and oligomeric [(phenylimino)methylidene]phosphines. In different solvents the benzyl compound was found to exist only as a mixture of [N,N′-(E)/(Z)]-isomeric 2,4-bis-(phenylimino)-1,3-diphosphetanes 2a with their alkyl groups at the phosphorus atoms in trans position, whereas in case of the ethyl derivative 2b a second pair of [N,N′-(E)/(Z)]-isomeric dimers with their substituents in cis position and two trimeric forms ( 3b and 4b ) could be detected in cyclopentane. [N,N′-(E)]-1r,3t-dibenzyl- ( 2a ) and [N,N′-(E)]-1r,3t-diethyl-2,4-bis(phenylimino)-1,3-diphosphetane 2b isolated from 1,2-dimethoxyethane or cyclopentane, crystallize in the monoclinic space group P2₁/c or P2₁/n, resp., with following dimensions of the unit cell determined at temperatures of measurement of +20 ± 3°C/?130 ± 3°C: a = 2145.4(1)/569.3(1); b = 568.1(2)/719.1(2); c = 1960.2(2)/2042.6(4) pm; β 99.43(1)°/95.03(2)°; Z = (2+2) and 2, resp. X-ray structure determinations (R_w = 0.034/0.041) show both molecules to be centrosymmetric. Characteristic rounded bond lengths (pm) and angles (°) are: endocyclic P? C 185/184; C? P? C 82/81; P? C? P 98/99; exocyclic P? C 186/184; C?N l27/127; C?N? C 121/11.