Cyclobuten‐Ringöffnung: Eine nützliche Reaktion zur Synthese doppelsträngiger Moleküle

Cyclobutene Ring Opening: A Useful Reaction for the Synthesis of Double‐Stranded Molecules Syntheses and ring‐opening reactions of the compounds endo ‐ 5a – e and 9a – c , all containing cyclobutene rings, are described. From these experiments it is concluded that compound 9a is a useful AB‐type Diels‐Alder monomer for the synthesis of well‐defined double‐stranded molecules. The stereochemistry of the adducts endo ‐ 4b and endo ‐ 5d is determined by X‐ray structure analysis.