Piperidine treatment, hot

Incorporation of an anthraquinone moiety, attached through an acyclic backbone unit, into a duplex DNA such that the anthraquinone was opposed to 5-methyl-dC resulted in an efficient one-electron oxidation to 5-formyl-dC or 5-hydroxymethyl-dC. Treatment of the duplex with hot piperidine led to strand-specific cleavage at the oxidised cytosine base. An anthraquinone has been used to link chimeric a-p oligonucleotides for formation of alternate-stranded triplexes. The two oligonucleotides were linked through a substituted propionic acid derivative which was further conjugated to the anthraquinone via various polyamines. 

Benzoyldiaryl ethers are cyclized in good-to-excellent yield by treatment with hot sulphuric acid-acetic acid [3027,3029]. A 2-aminopyran ring is formed when a heterocyclic ketone is heated with a cinnamonitrile and piperidine [3095]. Reduced chromen-5-one are also formed in a basic medium when acroleins are heated with 1,3-cyclohexanediones [2763a]. 

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