Makoto Nitta

Stereoselective cyclization of δ-alkenylamines catalyzed with butyllithium. Synthesis of cis-N-methyl-2,5-disubstituted pyrrolidines

Abstract Treatment of δ-alkenylamines ( 1a-1d ) with a catalytic amount of butyllithium gave cis-N -methyl-2,5-disubstituted pyrrolidines ( 2a-2d ) stereoselectively in good yields.

The Sinthesis and Chemical Properties of 11H-Cyclohepr[b]indeno[2,1-d]pyrrole

The reaction of N-(3-indenyl)iminotributylphosphorane with 2-chlorotropone gave novel 11H-cyclohept[b]indeno[2,1-d]pyrrole, which was converted to the corresponding ketone and alcohol. The chemical properties of the three compounds were studied

Metal-carbonyl-induced reaction of isoxazoles. Ring cleavage and reduction by hexacarbonylmolybdenum, pentacarbonyliron, or nonacarbonyldi-iron

In the presence of [Mo(CO)6] and water the isoxazoles (1a–f) undergo thermally induced reductive cleavage of the N–O bond to give β-amino enones in good yield. Similar results were obtained by the use of [Fe(CO)5] and water with photoirradiation, or of [Fe2(CO)9] and water with heating. A mechanism involving an N-complexed isoxazolepentacarbonylmolybdenum or isoxazoletetracarbonyliron, and a [Mo(CO)5]- or [Fe(CO)4]-complexed (β-oxo vinyl)nitrene intermediate is proposed for the reactions. The complexed nitrene moiety could be reduced by the central metal in the presence of water to give amine. Furthermore, treatment of 2-benzoyl-3-phenyl-2H-azirine (8a), which is an isomer of 3,5-diphenylisoxazole, with the metal carbonyls and water also resulted in the formation of a β-amino enone possibly via the corresponding complexed (β-oxo vinyl)nitrene. An N-complexed isoxazolepentacarbonylmolybdenum intermediate was prepared by the photoreaction of [Mo(CO)6] with 3,5-dimethylisoxazoie. Its characterization, and chemical transformations, have been carried out to investigate the proposed mechanism.

Synthesis, properties, and redox ability of optically active 3-carbamoyl-1,6-dimethylpyrimido[4,5-c]pyridazine-5,7(1H, 6H)-dione and related pyrimido-annulated pyridine analogues

Optically active 3-carbamoyl-1,6-dimethylpyrimido[4,5-c]pyridazine-5,7(1H,6H)-dione (13a) and related pyrimido-annulated pyridine analogues (13b,c) were prepared via the corresponding 3-ethoxycarbonyl-1,6-dimethylpyrimido[4,5-c]pydazine-5,7(1H,6H)-dione (11a) and the related compounds (11b,c). The properties of lla-c, 13a-c, and the related 1,3,6-trimethylpyrimido[4,5-c]pyridazine-5,7(1H,6H)-dione (18a) as well as 7-phenyl-and 3,7,8-trimethyl-pyrido[2,3-d]pyrimidine-2,4(3H,8H)-dione (18b,c) having no carbamoyl or ester function were studied by the UV-VIS spectra and redox potentials. Although pyridazine derivative (13a) was not reduced, pyridine derivatives (11b,c), (13b), and (18b) were reduced by Na 2 S 2 O 4 to give dihydrogenated compounds (20b,c), (21b), and (22b), respectively. The photo-induced oxidation reactions of 13a,b and 18a-c toward some amines under aerobic conditions were studied to give the corresponding imines in more than 100% yields [based on compounds 13a,b and 18a-c], suggesting that the oxidation proceeds in an autorecycling process.

A NOVEL ROUTE TO 1-AZAAZULENES BY THE REACTION OF BETA -AMINO ENONES WITH ACTIVATED TROPONES

The reaction of β -amino enones with activated tropones (2-bromo-, 2-chloro-, and 2-tosyloxytropones) underwent an enamine alkylation followed by dehydrating condensation to give 1-azaazulene derivatives in modest yields

The reactions of N-vinyliminophosphoranes. Part 14. A short new synthesis of [n](2,4)pyridinophane ring system (n= 9–6): static and dynamic structural studies of [7]- and [6](2,4)pyridinophanes

A short new synthesis of the [n](2,4)pyridinophane ring system (n= 9–6) consists of allowing N-vinyl- and N-(1-phenylvinyl)iminophosphoranes to react with cyclic α,β-unsaturated ketones. Structural studies of the compounds prepared were based on spectroscopic measurements and MNDO calculations. The 1H and 13C NMR spectra at various temperatures showed dynamic behaviour for the oligomethylene chains of [7]- and [6]-(2,4)pyridinophane derivatives (8c,d). The energy barriers ΔGc‡ of the bridge flipping are 12–13 kcal mol–1(Tc, 20 °C) for (8c) and 21–22 kcal mol–1 kcal mol–1(Tc, 150° C) for (8d). The lower-energy process of the oligomethylene chain in (8d) is the pseudorotation with Ea= 10.3 ± 0.2 kcal mol–1, ΔH‡= 9.8 ± 0.2 kcal mol–1, and ΔS‡=–4.8 cal mol–1 deg–1. Two stable conformations of the hexamethylene bridge of (8d) were unambiguously determined by low-temperature NMR. The strain of the [n](2,4)pyridinophane ring system was found to increase as the chain length becomes shorter. Remarkable deformation of the pyridine rings of (8c,d) was suggested by the geometrical optimization by MNDO calculation and the red shift of the UV spectrum.

Nonacarbonyldiiron-induced reaction of 2-oxa-3-azabicyclo[3.2.0]hepta-3,6-diene system. Preparation and thermal behavior of the cyclobutene-iron complex

La reaction du titre donne le (η 2 -phenyl-4 oxa-2 aza-3 bicyclo [3.2.0] heptadiene-3,6)-Fe(CO) 4 . Comportement thermique du complexe

On the reactions of 6-phosphoranylideneaminouracils and related 6-aminouracils with 2,4,6-cyclooctatrienone: Reactions of the intermediates of uracil-annulated 8-azabicyclo[5.3.1]undecatetraene ring systems

The reaction of 1,3-dimethyl-6-phosphoranylideneaminouracil (4) with 2,4,6-cyclooctatrienone (7) in AcOH gives an intermediacy of uracil-annulated 8-azabicyclo[5.3 1]undeca-2,4,7,9-tetraene (9), which results in the formation of 9-acetoxy-5a,10-methano-2,4-dimethyl-2H-5,5a,6,8a,9,10-hexahydrocyclopent[b]-pyrimido[5,4-f]azepine-1,3(4H)-dione and 1,3,7- and 1,3,5-trimethylpyrido[2,3-d]pyrimidine-2(1H),4(3H)-diones (12 and 13) after several reaction sequences. A similar reaction using 6-amino-1,3-dimethyluracil (5) also afforded the same products probably via uracil-annulated 8-azabicyclo[5.3.1]undeca-2,4,6,9-tetraene (14). A similar intermediate is also postulated in the reaction of 3-methyl-6-methylaminouracil (6) with 2,4,6-cyclooctatrienone, and results in the formation of 9-acetoxy-5a,10-methano-2,4,5-trimethyl-2H-5,5a,6,8a,9,10-hexahydrocyclopent-[b]pyrimido[5,4-f]azepine-1,3(4H)-dione (26), 3,7,8- and 3,5,8-trimethylpyrido-[2,3-d]pyrimidine-2(3H),4(8H)-diones (27 and 28).

On the reactivity of tricarbonyl(1–4-η-cyclohepta-1,3,5-triene)iron derivatives: C–C bond formation of tricarbonyl(cycloheptatrienide)irons with 2-chlorotropone

Tricarbonyl(1–4-η-cyclohepta-1,3,5-triene)iron derivatives [(RC7H7)Fe(CO)3](R = H, OMe, CN, and Ph)(4a–d) have been prepared and a study made of the nucleophilic attack of 2-chlorotropone by their corresponding anions. The tricarbonyl(cycloheptatrienide) iron and tricarbonyl(methoxycycloheptatrienide)iron undergo the reaction to give tricarbonyl[1–4-η-7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene]iron (7a) and tricarbonyl[1–4-η-6-methoxy-7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene] iron (7b), respectively. In contrast, tricarbonyl (cyanocycloheptatrienide)iron reacted with 2-chlorotropone to afford tricarbonyl[1–4-η-6-cyano-7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene]iron (7c) and tricarbonyl[1–4-η-5-cyano-7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene] iron (9c) in a ratio of (7c)/(9c)=1:5.6. Similarly, tricarbonyl(phenylcycloheptatrienide)iron with 2-chlorotropone also affords two products, tricarbonyl[1–4-η-6-phenyl-7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene]iron (7d) and tricarbonyl[1–4-η-2-phenyl-7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene]iron (10d), in a ratio of (7d)/(10d)= 3 : 1. The selective formation of (7b) and the product ratios of (7c) : (9c) and (7d) : (10d) are discussed on the basis of the electronic and steric factors of the substituent in the formally unco-ordinated allyl anion on the cycloheptatrienide ring. The stereochemistry of the tropone nucleus at C-7 is deduced to be exo to the [Fe(CO)3] entity on the basis of 1H n.m.r. spectral results. The products (7a, b, d) are easily decomplexed by trimethylamine oxide to give 7-(2-oxocyclohepta-1,3,5-trienyl)- and 1-substituted 7-(2-oxocyclohepta-1,3,5-trienyl)cyclohepta-1,3,5-triene derivatives in good yields.

On the reaction of tricarbonyl (4―7-η-1H-1,2-diazepine)iron with activated acetylenes: preparation of 1-vinyl-1H-1,2-diazepine derivatives

Addition reactions of tricarbonyl(4–7-η-1H-1,2-diazepine)iron (2a) to the triple bond of dimethyl acetylenedicarboxylate (DMAD), methyl propiolate (MP), and dibenzoylacetylene (DBA) have been investigated. The stereochemical outcome is influenced by the solvent system and the acetylenic compounds employed. While the reaction of (2a) with DMAD in an aprotic solvent afforded the syn-adduct (3a) as the major product in a protic solvent the reaction resulted in inversion of stereoselectivity to give predominantly the anti-adduct (4a). The reaction of (2a) with MP or with DBA exhibited a similar change in stereoselectivity, although MP has preferential syn selectivity and DBA has high anti-selectivity. The addition reactions of 3-methyl- and 5-methyl-derivatives of (2a) with DMAD have also been studied in order to confirm the mechanism of these reactions. The decomplexation reactions of several adducts have also been studied, with a view to the preparation of 1-vinyl-1H-1,2-diazepine derivatives.