Carbon-nitrogen rings

Nitrogen-containing 15-membered trialkyne macrocycles, such as l,6,ll-frw(aiylsulfonyl)-l,6,ll-triazacyclopentadeca-3,8,13-triynes and enediynes as 1,6,11-frw(arylsulfonyl)-1,6,11-triazacyclopentadeca-3-ene-8,13-diynes have been prepared and subjected to a [2+2+2]-cyclotrimerization process catalyzed by transition metal complexes, e.g., RhCl(CO)(PPh3)2 05JOC2033 . The reaction of pemosylated diethylenetriamine and 2-substituted propan-1,3- 

The novel preparation of 5-cyano[n](2,4)pyridinophane-6-ones [n = 6 (5%), 7 (11%), 8 (63%), 9 (71%)] was conducted by allowing cyanoacetatoamide to react with cycloalk-2-enones 05OBC638 . Pd-Catalyzed amination of either 3,5-dibromo- or 3,5-dichloropyridine with linear polyamines led to the formation of a new family of pyridine-containing macrocycles (e.g. 6) possessing an exo -oriented pyridine iV-atoms 05HCA1983 . The treatment of 3,5- 

A new methodology has appeared where 1-acyldipyrromethane was converted into the Pd-chelate of tram-A2B2 porphyrin in a one-flask reaction, in which the 1-acyldipyrromethane in refluxing EtOH containing KOH and Pd(MeCN)2 exposed to air simply self-condensed 05JOC3500 . Treatment of 4,7-dihydro-4,7-ethano-27/-isoindole and pentafluorobenzaldehyde 

---

Bases The bases in DNA have carbon-nitrogen ring structures because of the nitrogen... 

Fig. 1. Benzazepine formation by carbon-nitrogen ring closure.

---