2'-C-branched ribonucleosides. 2. Synthesis of 2'-C-beta-trifluoromethyl pyrimidine ribonucleosides

[structure: see text]. The first synthesis of 2'-C-beta-trifluoromethyl pyrimidine ribonucleosides is described. 1,2,3,5-Tetra-O-benzoyl-2-C-beta-trifluoromethyl-alpha-D-ribofuranose (3) is prepared from 1,3,5-tri-O-benzoyl-alpha-D-ribofuranose (1) in three steps and converted to 3,5-di-O-benzoyl-2-C-beta-trifluoromethyl-alpha-D-1-ribofuranosyl bromide (5). The 1-bromo derivative (5) is found to be a powerful reaction intermediate for the synthesis of ribonucleosides. The reaction of silylated pyrimidines with (5) in the presence of HgO/HgBr2 affords exclusively the beta-anomers (6-8). Deprotection of (6-8) with ammonia in methanol yields the 2'-C-beta-trifluoromethyl nucleosides (9-11).     

Interaction of 2-Aminoindoles with Tetracyanoethylene. 2. 3-Dicyano-methylene-2-iminoindolines

3-Dicyanomethylene-2-iminoindolines are obtained on interacting 2-aminoindoles with tetracyanoethylene in acidic medium. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1515–1520, October, 2005.     

An Ab Initio Study of C2H2.H2, C2H2.N2, and C2H2.Ar Complexes

Ab initio calculations at the post Hartree–Fock level were performed on complexes of acetylene with hydrogen, nitrogen, and argon. Total energies, optimum geometries, and binding energies were calculated, using the 6-311G** and the 6-31+G(2df,2pd) basis sets. Calculations showed the complexes to be more stable than the separate entities, with the exception of the acetylene–hydrogen complex.     

Pyrimidones. 2. Synthesis and reactions of 2-chloropyrimidines

The treatment of 1-alkyl-5-aryl and 1-alkyl-4,5-diaryl-2-(1H)pyrimidones with phosphorus oxychloride and phosphorus pentachloride resulted in chlorination and dealkylation to furnish 2-chloro-5-aryl (or 4,5-diaryl)-pyrimidines. These chlorpyrimidines were reacted with a variety of nitrogen, oxygen, sulfur, and carbon nucleophiles to produce the corresponding 2-substituted pyrimidines. In the case of phenyllithium, attack occurred at the 4-position of the pyrimidine ring yielding 11 . Triazolopyrimidine 9 was synthesized via the treatment of 2d with hydrazine followed by reaction with triethyl orthoformate.     

Reactivity of 2-halo-2H-azirines. 1. Reactions with nucleophiles.

Nucleophilic substitution reactions of 2-halo-2H-azirines 1a, 1b, 1d, and 1e with potassium phthalimide and aniline allowed the preparation of new substituted 2H-azirines 2-5. The reactions of 2-bromo-2H-azirine 1a with methylamine led to the synthesis of alpha-diimines 7 and 8. 2-Halo-2H-azirines were also established as building blocks for the synthesis of a range of heterocyclic compounds, namely, quinoxalines 10a-10d, 3-oxazoline 14, and 2H-[1,4]oxazines 18 and 20. X-ray crystal structures of alpha-diimine 7, 3-oxazoline 14, and 2H-[1,4]oxazine 18 are reported.     

2-Amino-2-thiazoline. V. phenylthioureido and phenylureido derivatives of 2-thiazoline

The reaction of 2-amino-2-thiazoline (I) with phenylisothiocyanate has been reported to give 2-imino-3-phenylthiocarbamoylthiazolidine (II) at low temperatures and l-phenyl-3-(2-thiazolin-2-yl)-2-thiourea (III) at ca. 100°. When performed by us, however, this reaction gave only a single mono-adduct regardless of the temperature. Nmr and chemical evidence indicates that structure III is the correct one. Treatment of I with phenylisocyanate also gave a mono-adduct which was established to be l-phenyl-3-(2-thiazolin-2-yl)urea (V). Compound I does not form a simple di-adduct with excess phenylisothiocyanate but does so with phenylisocyanate to give 2-phenylcarbamoylimino-3-phenylcarbamoylthiazolidine (VI). The reaction of III with phenylisocyanate gives 2-phenylthiocarbamoylimino-3-phenylcarbamoylthiazolidine (VII), however, the corresponding reaction of V with phenylisothiocyanate does not give the anticipated product but a mixture of compounds which includes VI and VII.     

2-Polyfluoroalkylchromones. 6. Synthesis of substituted 2-morpholino-2-trifluoromethylchroman-4-ones

Morpholine adds smoothly at the double bond of substituted 5- and 8-nitro-2-trifluoromethylchromones to form the corresponding 2-morpholino-2-trifluoromethylchroman-4-ones. 6-Methoxy-5-nitro-2-trifluoromethylchromone adds also benzylamine, whereas 7-methoxy-8-nitro-2-trifluoromethylchromone undergoes ring opening under the action of benzylamine to give 3-benzylamino-4,4,4-trifluoro-1-(2-hydroxy-4-methoxy-3-nitrophenyl)but-2-en-1-one.     

Diazines. IX. Metalation of 2-chloro, 2-methoxy and 2-pivaloylaminoquinoxaline

The lithiation of 2-chloro, 2-methoxy and 2-pivaloylaminoquinoxaline was studied. In the case of 2-chloro and 2-methoxyquinoxaline the simultaneous formation of dimers could not be avoided. The resulting lithio derivatives were reacted with carbonyl compounds and iodine. Yields in excess of 50% were obtained.     

Antiandrogen. I. 2-azapregnane and 2-oxapregnane steroids.

2-Azachlormadinone acetate (5a, 17-acetoxy-6-chloro-2-azapregna-4,6-diene- 3,20-dione), 2-oxachlormadinone acetate (6, 17-acetoxy-6-chloro-2-oxapregna-4,6-diene-3,20-dione) and the derivatives were prepared as potential antiandrogenic agents. Biological evaluation showed that 5a and 6 had a potent antiandrogenic activity when tested in the castrated male rat.     

Polyethers. I. Polymerization of 2-methyl-2-butene oxide

2-Methyl-2-butene oxide (2,3-epoxy-2-methylbutane) was polymerized with modified alkylaluminum initiators a t low temperatures to a high-melting, crystalline, film-forming polymer. High yields and comparatively high molecular weights were obtained with Al(i-Bu)₃?xH₂O initiators in inert diluents. When such initiators were modified with acetylacetone they became ineffective. Ammonia could be substituted for water in formulating an active initiator. Attempts to prepare an active initiator in the presence of the monomer were unsuccessful indicsting competition with the water for Al(i-Bu)₃. Thermal decomposition of the polymer produced methyl isopropyl ketone with some pivaldehyde.     

2-Polyfluoroalkylchromones. 7. Reactions of 6-substituted 2-tetra- and 2-pentafluoroethylchromones with 2-aminoethanol

The reactions of 2-aminoethanol with 6-methyl-2-tetra- and 6-methyl-2-pentafluoroethylchromones involve the carbonyl group to give imines; the reactions with 6-nitro-2-tetra- and 6-nitro-2-pentafluoroethylchromones involve the C(2) atom, resulting in the pyrone ring opening. This also occurs in the reactions of 2-(1,1,2,2-tetrafluoroethyl)chromone with ammonia and benzylamine.     

4-Hydroxy-2-quinolones. 2. Simple synthesis of arboricine

Acylation of methyl N-methylanthranilate with phenylacetyl chloride with subsequent intramolecular cyclization of the resulting anilide was used to synthesize 1-methyl-3-phenyl-4-hydroxy-2-quinolone (arboricine).See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 522–524, April, 1992.     

2-Polyfluoroalkylchromones. 5. Nitration and chlorination of 2-trifluoromethylchromones

Electrophilic nitration of 2-trifluoromethylchromone and its 6- and 7-methoxy derivatives affords 6-, 5-, and 8-nitro derivatives, respectively, while 5,7-dimethyl-2-trifluoromethylchromone yields a 6,8-dinitro derivative. Radical chlorination results in 3-chloro derivatives.     

Lithiation of Pyrrol-2-Acetic Acids. Synthesis of 2-Alkylpyrroles.

N-methylpyrrol-2-acetic acid and pyrrol-2-acetic acid were converted into di- and trianions on reaction with two equivalents of lithium diisopropylamide or three equivalents of t-butyllithium, respectively. Reaction of the anions with one equivalent of an alkyl bromide or iodide gave the corresponding mono-α-substituted acetic acids which on thermal decarboxylation gave pure 2-alkylpyrroles.     

Dioscorone. Regioselective Oxxmercuration of 2-Azabicyclo[2. 2]oct-5-ene

Oxymercuration of 2-azabicylo[2.2.2]oct-5-ane 1 occurs regioselectively to give a50:50 mixture of 5-syn-and 5-anti-isoquinculidinols 2 which can be converted to dioscorone 5.