✍ Scribed by Shadpour E. Mallakpour; Heinz Kolshorn; Dieter Schollmeyer; Reimund Stadler
No coin nor oath required. For personal study only.
In contrast to other electron deficient enophiles or dienophiles which react with 1,4‐cyclohexadiene (1,4‐CHD) under aromatization, 1,2,4‐triazoline‐3,5‐diones react in a defined reaction sequence. In a first step the 1,4‐cyclohexadiene reacts via an ene‐reaction. The intermediately formed substituted 1,3‐cyclohexadiene immediately reacts in a Diels‐Alder reaction. The regiochemistry of the Diels‐Alder reaction is controlled by the solvent polarity. This reaction sequence can be used to synthesize polymers. Low‐molarmass model compounds were synthesized to elucidate the stereochemistry of the polymers. By varying the bistriazolinedione, polymers with backbones of different rigidity are available.
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Cis-9,10-dihydro-9,10-ethanoanthracene-11-12-dicarboxylic acid anhydride (1) was converted into its amic acid derivative by reaction with L-leucine. The cyclization reaction was carried out in situ using triethylamine to give the succinic imide-acid derivative (2). Compound (2) was converted to the
## Abstract New spirocyclic heterocycles **8, 16, 19/20, 25, 27**, and **30** derived from pyrimido[4,5‐__b__][1,4]diazepin]‐8′(9′__H__)‐one were synthesised by a tandem nitroso‐ene/__Diels–Alder__ reaction of 4‐(alkenoylamino)‐5‐nitrosopyrimides. The crystal structure of **16** was established by
## Abstract The 2,5‐dimethylidene‐3,6‐bis[(__Z__)‐(2‐nitrophenyl)sulfenylmethylidene]‐7‐oxabicyclo[2.2.1]heptane (**13**) can be used to generate polyfunctional and multicyclic molecules with high regio‐ and stereoselectivity __via__ two successive __Diels__‐__Alder__ additions using two different