Takane Uchida

Mannich Reactions of Indoles with Dichloromethane and Secondary Amines under High Pressure

Mannich reactions of indole with dichloromethane and secondary amines gave the corresponding Mannich bases in moderate to good yields, while 2-methylindole afforded only low yields of the Mannich bases. Some limitations were observed in the cases of hindered amines and 2-phenylindole

Cycloaddition reactions of 6-cyanobenz[a]indolizines with activated alkynes. Formation of benzo[2.2.3]- and [2.3.4]cyclazines

Cycloaddition reactions of 6-cyanobenz[a]indolizines with activated alkynes such as dimethyl acetylenedicarboxylate, diacetylacetylene, methyl propiolate, methyl trimethylsilylpropiolate, methyl phenylpropiolate, and 4-phenyl-3-butyn-2-one were investigated.

Reactions of 5-Cyano-1,4-diphenylpyridazino[4,5-a]indolizines with Dimethyl Acetylenedicarboxylate: Regioselective Formation of 1:2 Michael Type Adducts

Reactions of 5-cyano-1,4-diphenylpyridazino[4,5-a]indolizines with dimethyl acetylenedicarboxylate afforded regioselectively the 1:2 adducts in a Michael fashion rather than in a 1,3-dipolar manner. The structure was established by an X-ray crystallography

Synthesis of stable 7-phosphanorbornadiene P-oxides

Nonbenzo-annelated stable 7-phosphanorbornadiene P-oxides have been prepared for the first time by the high pressure Diels-Alder reaction of 1,2,3,4,5-pentaphenylphosphole oxide with diaroylacetylenes. The P-oxides decompose around 100 o C to give the 1,2-diaroyl-3,4,5,6-tetraphenylbenzenes

Formation of an extremely unusual 1:2 adduct from 3-cyanoindolizines and dimethyl acetylenedicar☐ylate

Abstract Refluxing a mixture of 3-cyanoindolizine and dimethyl acetylenedicar☐ylate in toluene affords a 1:2 adduct, the structure of which is unambiguously determined by an X-ray analysis.

Synthesis of 2,3,4-triphenyl-3-azabicyclo[3.2.0]hepta-1,4-diene and its novel reaction with dimethyl acetylenedicarboxylate

A 3-azabicyclo[3.2.0]hepta-1,4-diene that is unsubstituted in the cyclobutene moiety has been prepared for the first time and undergoes a novel reaction with dimethyl acetylenedicarboxylate to give azepine 6.

Reaction of dicyanomethylides with 3-(3′,3′-dimethyltriazene-1-yl)- pyridine-4-carboxylic acid. Unexpected preferential formation of pyrido[4,3-a]indolizines

Abstract Contrary to theoretical predictions on the basis of a discrete hetaryne intermediate (frontier orbitals, total atomic charges on C-3 and C-4, and activation energies for the concerted process) from the MO calculations, reactions of dicyanomethylides with 3-(3′,3′-dimethyltriazene-1-yl)pyridine-4-carboxylic acid, a formal precursor of 3,4-didehydropyridine, afforded exclusively the pyrido[4,3-a]indolizines. The results are better in accord with a mechanism involving a zwitterionic hetaryne precursor.

Site selectivity in the 1,3-dipolar cycloaddition reaction of unsymmetric pyridinium bis(methoxycarbonyl)methylides with methyl propiolate

The 1,3-dipolar cycloaddition of unsymmetric pyridinium bis(methoxycarbonyl)methylides with methyl propiolate proceeds in moderate to good yields with high to moderate site selectivity with respect to the ylide. Polar 3-substituted pyridinium bis(methoxycarbonyl)methylides generally gave predominantly the corresponding 8-substituted indolizines regardless of the substituents. The results can be explained by dipole-dipole interactions

Cycloaddition reactions of cycloimmonium ylides with triphenylcyclopropene

Cycloaddition reactions of 1,2,3-triphenylcyclopropene (TPP) with a variety of substituted pyridinium dicyanomethylides (1) give the corresponding 1,2,3-triphenylindolizines (3)[and (4)], 6-cyano-7,8,9-triphenyl-4H-quinolizines (5), 4-cyano-1,2,3-triphenyl-4H-quinolizines (6), and/or 1 : 1 adducts (7)[and (8)], depending on the substituents and their positions. The effect of substituents on the course of the reaction is discussed qualitatively. The pyrazinium dicyanomethylide (16) with TPP produces the 7-azaindolizine (19), whereas pyridazinium (17) and phthalazinium (18) dicyanomethylides give the primary adducts (20) and (21), respectively. Reaction of pyridinium bis(alkoxycarbonyl)methylides (22) with TPP gives, however, generally poor or no yield of the indolizines.

Nitrogen 14 NMR and Correlations of Oxidation Potentials of Dibenzo[a,d]cycl[2.2.3]azines with the Corresponding HOMOs: Further Evidence for Peripheral Conjugate System

For the first time, 14 N NMR spectra of a novel type of heterocycles, dibenzo|a,d|cycl|2.2.3|azines were described. The chemical shifts are almost independent of substituents at position 2. The correlations of oxidation potentials with HOMO energies of dibenzo|a,d|cycl|2.2.3|azines also offer very good correlation coefficients (r 2 >0.92) regardless of calculation methods at various levels. Thus, it was concluded that the contribution of the unshared electron pairs of the central nitrogen to the peripheral conjugation in this system is almost negligible.