Studies on the syntheses of heterocyclic compounds. Part DCXII. A simple synthesis of benzopyran and dibenzopyran derivatives

trans-2-(3-Hydroxyphenyl)cyclohexanol (1b) was converted into 6-methyl-6-phenylbenzopyran (11a) and 6-spirocyclohexanobenzopyran (11b) by phenolic cyclization or under acidic condition. This type of reaction was also applied to the synthesis of 3,4-dihydro-6-methoxy-1-methoxycarbonyl-1-methyl-1H-2-benzopyran (IV).     

Studies on the syntheses of heterocyclic compounds. Part DXCVII. A synthesis of dienone analogs by electrolytic oxidation

Electrolytic coupling reaction of laudanosine (1) gave the O-methylflavinantine (II). N-Ethoxycarbonylated dihydrostilbene (IVa) gave a rearranged dienone (Va) and N-trifluoro-acetylated dihydrostilbene (IVb) contrastively gave an unrearranged dienone (Vb).     

A synthesis of O-ethylcularidine (studies on the syntheses of heterocyclic compounds. Part cccxxxiii

In order to confirm the structure of cularidine (I), O-ethylcularidine (II) was synthesized and shown to be identical with the naturally occurring O-ethyleularidine on the basis of NMR spectroscopy and the R_f values.     

Studies on the syntheses of heterocyclic compounds. Part DCXLIV . Catalytic reduction of homoproaporphine related compounds

Hydrogenation of the homoproaporphine (IV) over platinum oxide gave a mixture of the cyclohexanols VIIa and VIIb. In contrast, reduction of IV on palladium provided the cyclo-hexanone VI, which was also obtained from VIIb by oxidation. Treatment of the cyclohexanols VIIa and VIIb under hydrogen on platinum oxide afforded the same mixture of VIIa and VIIb.     

Studies on the syntheses of heterocyclic compounds. Part CCLXXIII. Synthesis of C-nordihydrocorynantheol and its related compounds

Mannich reaction of tryptamine with 3,3,4-triethoxycarbonylhexaldehyde (IV) gave the cyclized product (VIII), whose hydrolysis, followed by decarboxylation, afforded the acid (IX). After esterification of IX, reduction of ester (X) with lithium aluminum hydride gave the C-nordihydrocorynantheol (II). The syntheses of IV and XV were also described. Furthermore, the Mannich reaction of L-N-benzyl-1-methyltryptophan methyl ester (XV) with IV was also examined. This reaction gave the ester (XVII), which was hydrolyzed and decarboxylated to give the acid (XVIII). Esterification of XVIII, followed by catalytic hydrogenation, gave the lactam (III).     

Enzymic phenol oxidation of N-methylcoclaurine. Studies on the syntheses of heterocyclic compounds. Part cccxxxii

The enzymic phenol oxidation of N-methylcoclaurine (111) with homogenized potato peels in the presence of hydrogen peroxide was examined and found to give a mixture of the dimer (VI) and trimer (VII) with C-O-C head to tail coupling. Furthermore, the same oxidation of III with homogenized rhizome of Nelumbo nucifera Gartner and hydrogen peroxide was also investigated.     

Studies on the syntheses of heterocyclic compounds. Part DLIV. A total synthesis of (±)-coreximine by thermolysis

Thermolysis of the dibenzyloxy-substituted benzocyclobutene IXc effected cyclization and mono-O-debenzylation to provide a facile route to the total synthesis of the protoberberine isoquinoline (±)-coreximine (XIII).     

Studies on the syntheses of heterocyclic compounds. Part CCCXXX Synthesis of a homocularine type compound

An intramolecular Ullmann reaction of bromophenethylisoquinoline (X) was investigated in order to obtain the homocularine type compound (V), which could be one of the potential alkaloids belonging to 1-phenethylisoquinoline series. Methylation of the phenolic 8-hydroxyisoquinoline (XVIII), one of the position isomers which was separated by silica gel chromatography from a mixture of 6-hydroxy- (XVII) and 8-hydroxyisoquinoline (XVIII) prepared as usual, gave the starting material (X), which was cyclized by the Ullmann reaction in the presence of cupric oxide. The structure of our objective homocularine (V) was assigned from spectral data.     

Studies on the syntheses of azole derivatives. Part VIII. Photolysis of N-aryl-N-benzylearbamoyl azides [studies on the syntheses of heterocyclic compounds. Part CDXV

Photolysis of N-benzyl-N-phenylearbamoylazide (IVc) afforded 1-benzy 1-2-benzimidazolinone (Ic), 2-benzimidazolinone (IIe), 4-benzy 1-2-benzimidazolinone (IIe), and 5-benzy1-2-benzimidazo-linone (IIf)- The same reaction of N-benzyl-N-(4-chlorophenyl) carbamoyl azide (IVd) gave 3-benzyl-1-(phenylhydrazocarbonyl)-2-benzimidazolinone (VIb) besides the above four products. In the case of N-benzyl-4-(4-butoxyphenyl)carbamoyl azide (IVe), 1-benzy1-5-butoxy-2-benz-imidazolinone (1e), 5-butoxy-2-benzimidazolinone (IId), 5-benzy1-2-benzimidazolinone (IIf), and 4-benzy1-6-butoxy-2-benzimidazolinone (IIg).     

Ochotensine and related compounds. II. A synthesis of iso-ochotensine. (Studies on the syntheses of heterocyclic compounds. CCLXXV )

In order to examine the total syntheses of ochotensine (1) and ochotensimine (II), one of the isomers, iso-ochotensine (III), was synthesized as a preliminary experiment. Namely, Wittig reaction of VI, followed by treatment with sodium bicarbonate solution, gave the expected compound, 7-ethoxycarbonyl-3-ethoxycarbonyloxy-2-methoxy-13-methyIene-10,11-methyIene-dioxyochotensinan (VII) which was reduced with lithium aluminum hydride to give III. This was also obtained by methylation of 3-hydroxy-2-methoxy-13-methylene-10,11-methyIenedioxy-ochotensinan (VIII).     

Studies on the syntheses of heterocyclic compounds. Part CCCXXIX. Syntheses of i-spiroisoquinoline derivatives by phenolic cyclization

Phenolic cyclization of 2-(3-hydroxyphenyl)-2-methylethylamine (XIIIa) and 2-(3-hydroxyphenyl)phenethylamine (XIIIb) with various carbonyl compounds afforded eight types of corresponding 1-spirocycloalkano- and 1-spiroheterocycloalkano-1,2,3,4-tetrahydroisoquinoline derivatives (1-VIII) and 1,1-disubstituted-1, 2,3,4-tetrahydroisoquinoline derivative (IX). The acetyl derivatives of VI and IX and the benzoyl derivatives of III and V were also prepared. In addition, a synthetic method for obtaining the starting phenethylamines was examined.     

Studies on the syntheses of heterocyclic compounds—DCXCIII: A total synthesis of atheroline by photolysis

Atheroline (3) an oxoaporphine alkaloid, has been synthesised by photolysis of 8 bromo 1-(3-hydroxy-4-methoxybenzoyl)-6,7-dimethoxyisoquinoline (13) in the presence of sodium hydroxide.     

Studies on the syntheses of heterocyclic compounds—DLIX : A synthesis of benzocarbazole derivatives by thermolysis

A thermal reaction of indolylmagnesium bromide (5) with 1-cyano-4,5-dimethoxybenzocyclobutene (6) gave a mixture of 6-cyano-5a, 6,11,11a-tetrahydro-8,9-dimethoxy-5H-benzo [b] carbazole (8a) and 6-cyano-5a, 6, 11, 11a-tetrahydro-9-hydroxy-8-methoxy-5H-benzo [b] carbazole (10). Compound 8a was easily converted to 6-cyano-8, 9-dimethoxy-5H-benzo [b] carbazole (12) by dehydrogenation on 30% Pd-C.     

Studies on the syntheses of heterocyclic compounds—DLXIX : One-step synthesis of dihydropyridocarbazole derivatives

Heating indole and 4,5-dibromomethyl-3-hydroxy-2-methylpyridine hydrobromide (10), followed by acetylation, gave the desired dihydropyrido[4.3-b]carbazole (12) and its structural isomer, dihydropyrido[3.4-b]carbazole (13). The structures of (12 and 13) were determined by UV spectral investigations of the corresponding dehydrogenated products, 4-acetoxy-3-methyl-6H-pyrido[4.3-b]carbazole (11) and 4-acetoxy-3-methyl-10H-pyrido[3.4-b]carbazole (14).On the other hand, the same reaction in the presence of sodium iodide afforded 12 together with four other coupling products which were not cyclized, such as (16, 17, 18), and a dimer.