5,6,7,8-tetrahydroquinoline 2- pyrimidine

The relative ease of the reaction with the (l,l-dicyanopentynyl)pyrimi-dines induced studies of the reaction of 5-R-2-(l,l-dicyanohex-5-yn-1-yl)pyrimidine (R = H, NO2, Ar). They react with more difficulty, due to the longer tether between diene ad dienophile leading to a decreased entropic assistance. At a considerable higher temperature than observed for the (l,l-dicyanopentynyl)pyrimidines (210°C instead of 130°C and 8,8-dicyano-5,6,7,8-tetrahydroquinolines are formed (89T5151) (Scheme 33). 

The formation of a nitrene adjacent to a double bond can be used in the synthesis of novel heterocyclic systems. For example, the azide 721 converts smoothly into the tricyclic product 722 on irradiation and the same modus operandi is used for the synthesis of pyrrolo[2,3-J]pyrimidines from substituted 4-azidopyrimidines . Aziridine formation is also encountered in the cyclization of 723 to the tetrahydroquinoline derivatives 724 . Other cyclizations provide routes to imidazoindoles 725 " or thienopyrroles 726 . ... 

Jhh and " Jhh couplings have been measured by Katrizky et al for re-gioisomeric 3-[2- or 5-anilino-2-(alkylamino)phenyl]propanoic acids, 2H-1,4-benzothioazin-3(4/f)-ones and 2,3-dihydro-l,5-benzothiazepin-4(5if)-ones, by Suri et for a series of pyrido[l,2-a]pyrimidine derivatives, and by Laatsch and co-workers for helquinoline, a new tetrahydroquinoline antibiotic isolated from Janibacter limosus. The configuration around the double bonds and the epoxide stereochemistry of oximidine III, a new antitumor antibiotic against transformed cells from Pseudomonas sp., has been established on the basis of Vhh by Hayakawa et... 

The term ferf-amino effect is used to describe ring-closure of N, A -dialkyl-substituted anilines with an unsaturated electrophilic ortho substituent to afford fused tetrahydroquinolines [22] or other iV-heterocycles [15, 19, 20,46, 85-87]. The terf-amino effect has been widely utilized in the synthesis of pyridine, pyrimidine, and pyridazine derivatives, which has been well reviewed by Matyus et al. [15]. 

The oxidative aromatization of tetrahydro-5(l/f)-quinolinones and tetrahydropyrido [2,3-fif]pyrimidin-4(//)-one withpara-benzaldehydes as oxidants in NaOEt/EtOH results in the formation of the corresponding quinolone and aryl methanol because of the hydride transfer from tetrahydroquinoline to arylaldehydes during the oxidation process. The yield of the products basically depends on the substituents with -l-M effect attached to the para position of benzene rings connected to the 2- and 4-positions of the hydro-quinolinone moiety and substituents with -I effect attached to the aryl aldehydes. 

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