Quinolines 1,2,3,4-tetrahydro

Benzo h quinolin 1,2,3,4-Tetrahydro-E18, 575, 576 [Aren-Hydrier.] Biphenyl 4-Amino-2 -methyl- XI/I,... 

Tetrahydroquinoline Tetrahydro-iso-quinoline Indole Carbazole Piperazine... 

Reduction. Quinoline may be reduced rather selectively, depending on the reaction conditions. Raney nickel at 70—100°C and 6—7 MPa (60—70 atm) results in a 70% yield of 1,2,3,4-tetrahydroquinoline (32). Temperatures of 210—270°C produce only a slightly lower yield of decahydroquinoline [2051-28-7]. Catalytic reduction with platinum oxide in strongly acidic solution at ambient temperature and moderate pressure also gives a 70% yield of 5,6,7,8-tetrahydroquinoline [10500-57-9] (33). Further reduction of this material with sodium—ethanol produces 90% of /ra/ j -decahydroquinoline [767-92-0] (34). Reductions of the quinoline heterocycHc ring accompanied by alkylation have been reported (35). Yields vary widely sodium borohydride—acetic acid gives 17% of l,2,3,4-tetrahydro-l-(trifluoromethyl)quinoline [57928-03-7] and 79% of 1,2,3,4-tetrahydro-l-isopropylquinoline [21863-25-2]. This latter compound is obtained in the presence of acetone the use of cyanoborohydride reduces the pyridine ring without alkylation. 

H-Cyclopenta[7,8]naphtho[2,3-6]furan-7-yl glyoxylate, 2,3,6,10-tetrahydro-6-hydroxy-6-methyl-3,10-dioxo-, methyl ester H NMR. 4, 560 (66JCS(C)743) Cyclopenta[6]quinoline, 6,7,8,9-tetrahydro- C NMR, 2, 122 (77JOC300, 77JOC2742)... 

Naphtho[l,2-h]pyrylium salts, 5,6-dihydro-2,4-diphenyl-synthesis, 3, 869 Naphtho[2,l-h]pyrylium salts synthesis, 3, 866 Naphthoquinolines, tetrahydro-synthesis, 2, 469 N aphtho[ 1,2-7]quinolines Skraup synthesis, 2, 467... 

IH-chromene synthesis from, 3, 766 Quinoline, 4-acetoxy-1,2,3,4-tetrahydro-synthesis... 

Quinoline, 4-methyl-5,6,7,8-tetrahydro-synthesis, 2, 471 Quinoline, 2-methylthio-3-nitro-3-substituted... 

Other secondary amines such as pyrrolidine, di- -butylamine, tetrahydro-quinoline, n-benzylamine, and piperidine were also found to be capable of effecting this reduction. Interestingly, morpholine does not reduce enamines as readily (47) and its acid-catalyzed reaction with norbornanone was reported (45) to give only the corresponding enamine (93), although trace amounts of the reduction product were detected when cyclohexanone was treated with morpholine under these conditions (47a). The yield of morpholine reduction product was increased by using higher temperatures. 

When 3-phenyl-3//-triazolo[4,5-/]quinoline was heated at 390 00°C, IH-pyrido[2,3-c]carbazole 149 originated. Its structure could be confirmed by unambiguous synthesis from the 8,9,10,1 l-tetrahydro-7//-pyrido[2,3-c]carbazole (52CJC711). 

Phenyl-l, 2,3,6-tetrahydro[l, 3]thiazino[3,2-n]quinolin-6-ones 90 were prepared in the reactions of 2-mercapto-5-phenyl-l,4-dihydroquinolin-4-ones 103 and 1,3-dihalopropane in 55-79% yields (97JAP(K)97/278780). 

The Reisert compound 93, prepared from quinoline derivatives 92, gave upon reaction with dimethyl acetylenedicarboxylate the pyrroloquinoline 95. Reduction of 93 gave the tetrahydro derivative that upon reaction with dimethyl acetylenedicarboxylate afforded 96 (85JOC722). Reaction of 94 with acrylonitrile in presence of base gave pyrroloquinoline 97 (77JCS(P1)2018) (Scheme 18). 

Dimethoxy-2-(arylimino)-2,3,6,7-tetrahydro-4//-pyrimido[6,1 -n]iso-quinolin-4-ones were N-alkylated with A-(catalytic amount of I2 in boiling 2-butanone in 13-67% yields (00MIP19). 

---