The structures of open-chain bis-Reissert analogues and their salts were investigated using I3C NMR spectroscopy. Evidence is presented to show that the former exists in the acyclic form in solution. Detailed structural studies and the I3C NMR data clearly show that, in solution, the open-chain bis-Reissert salt analogues exist predominantly as the amino tautomer.

An open‐chain bis‐Reissert salt analog 5 has been synthesized and fully characterized. The reaction of the salt analog with methyl acrylate yields the pyrrole 7 which exists in solution in the azafulvene form 7a. The reaction of the salt analog with dimethylacetylene dicarboxylate (DMAD) affords the bispyrrole 9.

Use of video display terminals (VDTs) is associated with a decreased jkequency of blinking and an increased rate of tear evaporation. This leads to ocular fatigue (I), which is one of the major symptoms of dry eye (2). The causes or alterationsin the nonnal tearfllm that lead to dry eye syndrome or keratoconjunctivitis sicca are given here, followed by a brief account of the diagnostic measures. Various compounds and dosage forms that are in use and emerging for the treatment of dry eye are described. 6.5-7.6. The turnover of tears is heavily dependent on environmental conditions, such as temperature, relative humidity, and wind as well as age and the physiological state of the patient (7). The cul-de-sac normally holds 7-9 pL of tears but 465

Propionaldehyde (I), ethylenediamine (II), and KCN are coupled to yield the amino nitrile (III).

Das bei der sauren Verseifung des Dinitrils (I) zur Dicarbonsäure (III) als Zwischenprodukt auftretende Salz (II) wird isoliert.