Dedicated to Professor Klaus Weissermel on the occasion of his 60th birthdayBesides its technical meaning, the word "electronics" signifies another industrial revolution. The driving force behind this development is the very rapid progress in the field of integrated semiconductor circuits. An ever-increasing number of structures of ever-decreasing size must be accommodated on the same surface of the semiconductor crystal. This trend towards miniaturization embraces not only the integrated circuit but also its mounting panel, the printed circuit board; integrated circuits with 65 536 storage spaces, i. e. more than 100000 individual functions, on a semiconductor die of less than 1 cm2 are already standard today in industry. This micro-world, the potential of which can hardly be fully appreciated even today, has a direct appeal to all those of scientific inclination. However, the role of chemistry in the creation of this world becomes clear only on closer examination of the manufacturing processes: no mechanical tool is fine enough and no machine is sufficiently precise and rapid to work out complicated structures in the micron range with the required perfection. Chemistry first made possible the mass production of electronic components and consequently their widespread use today, and it is chemistry which will also play a decisive role in the future. Whether in the field of photoresists for the production of printed circuit boards with conductor widths of less than 100 pm, or in overcoming the 1 pm barrier in the manufacture of semiconductors using electron beam-and X-ray-resists, photochemistry, radiation chemistry, and polymer chemistry will have to develop new manufacturing processes and provide industrially utilizable materials.
Thermisch oder photochemisch induzierte Ringverengung von 2-Azido-3,3-difluorcyclobutenen 1, deren Syntbese aus den Cyclobutanen 3a, b und 6 beschrieben wird, liefert in guter Ausbeute die 2,2-Difluorcyclopropane 2. Ausgehend vom Oxim 15 ist 2 b auch durch basenkatalysierte Eliminierung aus dem 0-4-Nitrobenzolsulfonat zugdnglich. In Gegenwart nucleophiler Aromaten und von Furan eiitstehen aus l b und l i die ringerweitcrten Pyrrole 14. Ein Reaktionsmechanismus wird vorgeschlagen. Ring Contraction of Azidocyclobutenes to CyclopropanecarbonitrilesThermally or photochemically induced ring contraction of 2-azido-3,3-difluorocyclobutenes 1, the synthesis of which from the cyclobutancs 3a, b and 6 is described, leads to 2,2-difluorocyclopropanes 2 in good yields. 2 b is also accessible by base-catalysed elimination from the 0-4-nitrobenzenesullonate of the oxme 15. In the presence of nucleophilic arenes and furan 1 b and l i undergo ring expansion to pyrroles 14. A possible mechanism of these reactions is proposed.Eine Reihe ungesattigter sechs-und siebengliedriger cyclischer Azide sind tliermischl) und photochemischz) i n die ringvesengten Nitrile uberfuhrbar. Ausgehend von Funf-und Vierringanden wurden Cydncydo butan-und Cyancyclopropanverbindungen bisher nicht erhalten.Jedoch \el duf die kurzii~h veroffentlichte?) Dnrstellung von (I-Aminoathyl)cyclopropan dimh Reduklion von I -Azido-2-jod-I -methylcydo butan und von 1 -(I, 1 -Diazidoathyl)-Imethylcyclopropan durch Ein\iirkung von JodLhlord Lind Ndtriurndzld auf I ,2-l>imcthylcyclobuten hingewicsen.Wir fanden nun, da13 2-Azido-3,3-difluorcyclobutene I a-k be1 Bestrahlung mit Licht der Wellenlange A . 290 nm (@Sol~dexglasfilter) Stickstoff abspalten u n d sich mit guten Ausbeuten in die 2,2-Difluorcyclopropancarbonltrile 2a-k umuandeln. I 1) R. A . Abramovitch und E. P. K.kbu in S.
P,P-Dichloroa,a-diphenyiethylene (50). m.p. 80 "C 131 P,P-Dichloroa,a-diphenylethylene (85). m.p. 80°C [3] P,P-Dichloro-a,a-diphenylethylene (SO). m.p. 132 "C 141 P-Fluoro-P-chloro-a,a-diphenylethylene (50). m.p. 38 'C, b.p. 132"C/18 mm P,P-Dibromoa,a-diphenylethylene (20). m.p. 85 "C [51 P-Chloro-P-bromo-a,a-diphenylethylene (66). m.p. 132-134 O C P-Fluoro-8-bromou.a-diphenylethylene (50). m.p. 92-94 "C P-Chloro-@-phenyl-a,a-diphenylethylene (40). m.p. 120-122 "C 141 P-Bromo-P-phenyl-z,a-diphenylethylene (25). m.p. 130 "C 161
Die UV‐Bestrahlung wasserhaltiger Lösungen der Steroidketone I bzw. III liefert über eine Keten‐Zwischenstufe stereoselektiv nur eine der C‐13 epimeren, ringgeöffneten Carbonsäuren (II). Die in Gegenwart von Cyclohexylamin vorgenommene Belichtung führt beim Campher (IV) zu einer untergeordneten, beim Homocampher (XI) zu einer nennenswerten Amidbildung. Die photolytische Säurebildung vollzieht sich beim Homo‐Steroidketon XVII in erhöhtem Ausmaß und führt zum entsprechenden C‐13‐Epimerenpaar. Diese Beobachtungen lassen sich durch unterschiedliche Ringspannung in den Übergangszuständen der intramolekularen H‐Übertragung deuten. — Eine Methode zur Darstellung größerer Mengen von XI wird beschrieben.
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