Synthesis and anti-HIV-1 activity of a series of 1-(alkoxymethyl)-5-alkyl-6-(arylselenenyl)uracils and -2-thiouracils

A series of 1-(alkoxymethyl)-5-alkyl-6-(phenylselenenyl)uracils and -2-thiouracils modified at the 3- and/or 5-position of the C-6 phenylselenenyl ring with methyl or fluoro substituent has been synthesized and tested for their ability to inhibit HIV-1 replication. Lithiation of the acyclic uracil and 2-thiouracil derivatives 11-14 and 27-32 with lithium diisopropylamide or lithium bis(trimethylsilyl)amide followed by reaction with an appropriate diaryl diselenide afforded 6-arylselenenyl compounds 18-26 after removal of the tert-butyldimethylsilyl protecting group and 35-47 . Compounds 48-54 were prepared from compounds 38-44 by oxidative hydrolysis of the thione function. Of these compounds, 50 inhibited HIV -1 replication in human T₄ lymphoblastoid cells at a 50% effective concentration (EC₅₀) of 0.0047 μM with a selectivity index of >42600.     

PALLADIUM(0)-CATALYZED SYNTHESIS OF 2-PHENYL-2H-CHROMENE

ABSTRACT

2-Phenyl-2H-chromene is obtained in quite good yield starting from 3-[(2-tert-butyldimethylsilyl)oxyphenyl]prop-2-enal. Condensation of this aldehyde with phenyl magnesium bromide, followed by the acetylation of the alcohol obtained, and then intramolecular cyclization in the presence of a palladium catalyst gave the phenylchromene in an overall 34% yield.     

A DIRECT LITHIATION ROUTE TO 2-ACYL-1-(PHENYLSULFONYL)INDOLES

ABSTRACT

2-Acyl-1-(phenylsulfonyl)indoles (3, 7–9) are prepared in 75–84% yield from 1-(phenylsulfonyl)indoles (1, 5) in one operation by treatment of the latter with s-butyllithium followed by inverse quenching of the C-2 lithioindoles with carboxylic acid anhydrides (6).     

Preparation of (R)-11-hydroxyaporphine directly from (R)-10,11-dihydroxyaporphine ((R)-apomorphine)

A Regioselective synthesis of (R)-11-hydroxyaporphine 2 directly from (R)-10,11-dihydroxyaporphine ((R)-apomorphine, 1 ) is described for the first time. The isopropylidene ketal ring of 10,11-(isopropyl-idenyldioxy)aporphine 5 obtained by the isopropylidenation of apomorphine was regioselectively opened by ten equivalents of trimethylaluminum to give (R)-10-hydroxy-11-tert-butyloxyaporphine 6 . The free 10-hydioxyl position of 6 was triflated with N-pbenyltrifluoromethanesulfonimide and potassium carbonate under reflux to give (R)-10-[(trifluoromethyl)sulfonyloxy]-11-tert-butyloxyaporphine 7 . The reduced product, 11-tert-butyloxyaporphine 8 was prepared from 7 by a palladium-catalyzed hydrogenolysis. The ether cleavage of (R)-11-tert-butyloxyaporphine with 48% hydrobromic acid afforded the desired (R)-11-hydroxyaporphine 2 in good yield.     

Synthesis of 3,4,5-trisubstituted indoles via iterative directed lithiation of 1-(triisopropylsilyl)gramines

Directed lithiation of 1-(triisopropylsilyl)gramines 1 with tert-butyllithium followed by reaction with trimethylsilylmethyl azide produced 4-amino-1-(triisopropylsilyl)gramines 7. The N-tert-butoxycarbonyl derivatives 8 were lithiated selectively at C-5 with tert-butyllithium and the lithiated species were reacted with a variety of electrophiles to give 5-functionalized compounds, 9 and 10. A facile method to produce 3,4,5-trisubstituted indoles from readily available gramine derivatives is thereby established.     

Synthesis of 5-(3-Tert-Butylamino-2-Hydroxy) Propoxy-3,4-Dihydrocarbostyril

5-(3-tert-Butylamino-2-hydroxy) propoxy-3, 4-dihydrocarbostyril ( 1 , carteolol) was prepared by an acid-catalyzed cyclization of the N-pivaloylamino-ester ( 5 ), which was obtained by using organolithiation of m-pivaloylanisidine, followed by Wittig and catalytic hydrogenation reactions. The total yield of 1 obtained from m-anisidine ( 2 ) is 21%.     

Spirocyclization of 1-(o-aminophenyl)cycloalkanols and 1-(2′-amino-3′-pyridinyl)cycloalkanols

A one-step synthesis of spiro[cycloalkane-1,4′-2H-3′,1-benzoxazin]-2′-ones and spiro[cycloalkane-1,4′-1H-pyrido[2′,3′-d][1,3′]oxazin]-2′-ones, obtained in good yield from the corresponding 1-(o-aminophenyl) and 1-(2′-amino-3′-pyridinyl)cycloalkanols is described using ethyl carbonate in presence of n-butyllithium.     

2,3- and 3,4-Bis(diethoxyphosphorylmethyl)-5-tert-butylfurans

Reduction of 2-, 4-acetoxymethyl derivatives of 5-tert-butylfuran-3-carboxylic acid leads to the corresponding bis(hydroxymethyl)furans. Bis(chloromethyl)furans prepared from the latter were involvedin reaction with sodium diethyl phosphite. In the presence of two equivalents of a phosphorus-containing nucleophile, bis(phosphonomethyl)furans are formed. One equivalent of sodium diethyl phosphite reacts with 3,4-bis(chloromethyl)furan to give a mixture of 3-and 4-phosphorylated products in a 4.5:1 ratio in a low yield. The revealed difference in reactivity between the 3- and 4-chloromethyl groups demonstrates the importance of shielding of the chloromethyl group by the neighboring tert-butyl substituent. Examination of the ¹H NMR spectra of 3,4-bis(hydroxymethyl)-, 3,4-bis(chloromethyl)-, 3,4-bis(diethoxyphosphorylmethyl)-5-tert-butylfurans, and also specially prepared 5-tert-butyl-3-(diethoxyphosphorylmethyl)-4-(ethoxymethyl)-2-methylfuran established that the signal of the substituent neighboring to the tert-butyl group is always shifted downfield.     

Stereochemical differentiation and simultaneous analysis of 3-, 4-, and 5-hydroxyalkanoic acids from biopolyesters by multidimensional gas chromatography

The direct enantioselective analysis of 3-, 4-, and 5-hydroxy fatty acids from biological material has been achieved by enantioselective multidimensional gas chromatography (enantio-MDGC) with heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)- or (2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin as chiral stationary phase. All the bacteria investigated produced polyesters of enatiomerically pure (R) configured compounds.     

Total Syntheses of (−)-Conduritol B ((−)-1L-Cyclohex-5-ene-1,3/2,4-tetrol) and of (+)-Conduritol F((+)-1D-Cyclohex-5-ene-1,2,4/3-tetrol). Determination of the Absolute Configuration of (+)-Leucanthemito

The ‘naked sugar’ (+)-(1R,2R4R)-2-endo-cyano-7-oxabicyclo[2.2.1]hept-5-sn-2-exo-yl acetate ((+)- 4 ) was converted (7 steps, 45% overall) with high stereoselectivity into (?)-(4R,5S,6R)-4,5,6-tris{[(tert-butyl)dimethylsilyl]oxy}cyclohex-2-en-1-one ((?)- 11 ). Reduction of (?)- 1 with NaBH₄- CeCl₃ · 7 H₂O, followed by deprotection of the silyl ether moieties gave (+)-conduritol F ((+)- 1 ; 47%) whose characteristics were identical to those of natural (+)-leucanthemitol. Reduction of (?)- 11 with DIBAH, followed by deprotection of the silyl ether moiety led to (?)-conduritol B ((?)- 3 ; 51 %).     

Efficient and beta-Stereoselective Synthesis of 4(5)-(beta-D-Ribofuranosyl)- and 4(5)-(2-Deoxyribofuranosyl)imidazoles(1)

A synthetic route to 4(5)-(beta-D-ribofuranosyl)imidazole (1), starting from 2,3,5-tri-O-benzyl-D-ribose (5), was developed via a Mitsunobu cyclization. Reaction of 5 with the lithium salt of bis-protected imidazole afforded the corresponding 5-ribosylimidazole 7RS. Hydrolysis of 7RS gave a 1:1 mixture of diol isomers 8R and 8S having an unsubstituted imidazole. Mitsunobu cyclization of the mixture 8RS using N,N,N',N'-tetramethylazodicarboxamide and Bu(3)P exclusively afforded benzylated beta-ribofuranosyl imidazole 9beta in 92% yield, accompanied by alpha-anomer 9alpha, in a ratio of 26.3:1. The configuration of 9beta was established by X-ray crystallography of ethoxycarbonyl derivative 10beta. Reductive debenzylation of 9beta over Pd/C was carried out, and the synthesis of 1 was attained from starting 5 in four steps and 87% overall yield. This synthetic methodology was extended to the synthesis of 4(5)-(2-deoxy-beta-D-ribofuranosyl)imidazole (2). Mitsunobu cyclization of a 1:1 mixture of the corresponding diol isomers 14RS produced 15beta and 15alpha in a ratio of 5.4:1. The synthesis of 2 was attained in a 59% overall yield from the starting 3,5-di-O-benzyl-2-deoxy-D-ribose (12). beta-Stereoselective glycosylation in the key step is discussed and explained by intramolecular hydrogen bonding between an NH in the imidazole and the oxygen functional group in the sugar moiety.     

Synthesis of 1-(benzotriazol-1-yl)alkyldiphenylphosphine oxides and their transformations to novel benzotriazol-1-yl-substituted cyclopropanes

Diphenylphosphinous anion reacted with chloromethylbenzotriazole to give (benzotriazol-1-yl)methyldiphenylphosphine oxide, which, after lithiation, was alkylated to give 1-(benzotriazol-1-yl)alkyldiphenylphosphine oxides in good yield. Treatment of 1-(benzotriazol-1-yl)alkyldiphenylphosphine oxides with n-butyllithium followed by condensation with epoxides, afforded benzotriazol-1-yl-substituted cyclopropanes, which underwent further lithiation and subsequent reaction with numerous electrophiles to provide a variety of novel benzotriazol-1-yl-substituted cyclopropane derivatives.     

Functionalisation of 1,2,3-triazole via lithiation of 1-[2-(trimethylsilyl)ethoxy]methyl-1H-1,2,3-triazole

The preparation of a number of 5-substituted 1-[2-(trimethylsilyl)ethoxy]methyl-1H-1,2,3-triazoles via reaction of 1-[2-(trimethylsilyl)ethoxy]methyl-1H-1,2,3-triazole with n-butyllithium followed by addition of various electrophiles is reported. Removal of the protecting group by action of diluted aqueous hydrochloric acid or by tetrabutylammonium fluoride in tetrahydrofuran leads to the appropriate 4-substituted 1H-1,2,3-triazoles.     

Synthesis of 5S-(1-Oxoalkyl and Aryl)-2-pyrrolidinone Derivatives1

N-Benzyl pyroglutamate esters react with aryllithium reagents and methyllithium to give moderate to good yields of 5-(1-oxoaryl) or 5-(1-oxoalkyl)-2-pyrrolidinone derivatives. The reaction proceeds without racemization, but is accompanied by formation of 5-(1-hydroxy-1-alkyl)-2-pyrrolidinone derivatives. This reaction gives very poor yields of ketone products with most other alkyl organolithium reagents such as n-butyllithium. Grignard reagents react to give primarily the alcohol.     

Synthesis and Structure of 2,3-Bis(5-tert-butyl-2-methoxyphenyl)buta-1,3-diene by Bromine Elimination of (Z)-1,4-Dibromo-2,3-bis(5-tert-butyl-2-methoxyphenyl)-2-butene

2,3-Bis(5-tert-butyl-2-methoxyphenyl)buta-1,3-diene was prepared by bromination of (Z)- and (E)-2,3-bis(5-tert-butyl-2-methoxyphenyl)-2-butene followed by treatment with zinc powder in a mixture of CH₂Cl₂ and acetic acid, which was converted to the corresponding o-terphenyl skeleton by the condensation with dimethyl acetylenedicarboxylate followed by oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone.     

Short Synthesis of 1-(3-tert-Butyl-1-phenyl-1H-pyrazol-5-yl)-3-(5-(2-morpholinoethoxy)-2H-chromen-8-yl) Urea Derivatives

A short and efficient synthesis of 1-(3-tert-butyl-1-phenyl-1H-pyrazol-5-yl)-3-(5-(2-morpholinoethoxy)-2H-chromen-8-yl) urea derivatives (1a–c), a novel type of p38 MAPK inhibitors, is described. The Claisen thermal rearrangement of arylpropargyl ethers was employd as a key step to synthesize the chromene core. The solvent effect on the ratio of the resultant two isomers of Claisen thermal rearrangement, namely 2-methylbenzofuran and 2H-chromen, was also investigated.     

(E)- and (Z)-1-benzenesulfonyl-4-trimethylsilyl-2-butenes as (E)-1-(1,3-butadienyl) synthons

(E)- and (Z)-1-benzenesulfonyl-4-trimethylsilyl-2-butenes (E/Z=9), prepared from 4-trimethylsilyl-1-buten-3-ol, $\text{n}$-butyllithium and benzenesulfenyl chloride and oxidation of the intermediate (E)- and (Z)-1-benzenesulfinyl-4-trimethylsilyl-2-butenes with hydrogen peroxide, react with $\text{n}$-butyllithium and then primary halides to give 4-benzenesulfonyl-1-trimethylsilyl-2-alkenes which are rapidly 1,4-debenzenesulfonyltrimethylsilated to (E)-1,3-alkadienes by tetra-$\text{n}$-butylammonium fluoride at O°C.     

Procedure for the Rapid Synthesis of the Monomer 1,4-Bis(chloromethyl)-2-(2-ethylhexyloxy)-5-methoxybenzene

The alkylation of 4-methoxyphenol with 2-ethylhexyl bromide was accelerated by using potassium tert-butoxide in dimethylformamide. Subsequent chloromethylation occurred quickly using acetic acid as a cosolvent to give the poly[(2-(2-ethylhexyloxy)-5-methoxy-p-phenylene)vinylene] (MEH-PPV) monomer in 61% overall yield on a 2-mol scale.     

Synthesis and optical behaviors of 2-(9-phenanthrenyl)-, 2-(9-anthryl)-, and 2-(1-pyrenyl)-1-alkylimidazole homologues

Eight 2-(9-phenanthrenyl)-, 2-(9-anthryl)- and 2-(1-pyrenyl)-1-alkyl-benzimidazole compounds, three 2-(9-anthryl)-1-alkylphenanthroimidazole compounds and five 4,5-diphenyl-1-alkyl-2-(9-anthryl)imidazole compounds were synthesized by alkylation reactions of the corresponding benzimidazole, phenanthroimidazole or imidazole compounds. 2-(10-Bromo-9-anthryl)-1-alkyl-benzimidazole compounds were prepared by bromination reaction of 2-(9-anthryl)-1-alkylbenzimidazole compounds. All the synthesized compounds were characterized by elemental analysis, ¹H NMR, ¹³C NMR, MS or HRMS; their absorption coefficients (), maximum absorption λ_amax, fluorescence emission maximum λ_em, Stokes shifts and fluorescence quantum yields (Φ_F) in ethyl acetate were determined; their fluorescent lifetimes (T₁ and T₂) were measured in ethyl acetate and in solid state, respectively. The crystal structure of 2-(9-anthryl)-1-n-butyl-4,5-diphenylimidazole (12a) was determined to be triclinic, space group P-1 types, using single crystal X-ray crystallography technique. The results showed that these compounds exhibited moderate fluorescence-emission abilities and higher solubility in most organic solvents than their corresponding starting materials. The relationships between the optical behaviors and structures for these compounds were discussed.     

Synthesis and Circular Dichroism of Optically Pure (±)-(1S,2S,5S)-5-Methoxy-3,4,6,7-tetramethylidenebicyclo[3.2.1]oct-2-yl Derivatives. Baker's Yeast Reduction of 4-Methoxy-5,6,7,8-tetramethylidenebicyclo[2.2.2]octan-2-one

Baker's yeast reduction of 4-methoxy-5,6,7,8-tetramethylidenebicyclo[2.2.2]octan-2-one ( 11 ) under fermenting conditions afforded (?)-(1S,2S,4R)-4-methoxy-5,6,7,8-tetramethylidenebicyclo[2.2.2]octan-2-ol ((?)- 13 ) in 60% yield with an e.e. > 99.5%. Its methanesulfonate (?)- 14 was hydrolyzed and rearranged with high stereo-selectivity into (+)-(1S,2S,5S)-5-methoxy-3,4,6,7-tetramethylidenebicyclo[3.2.1]octan-2-ol ((+)- 15 ). The absolute configuration of (?)- 13 was deduced from the CD spectrum of its 4-(dimethylamino)benzoate ((+)- 22 ) applying the chiral exciton-coupling method. The CD spectrum of (+)- 15 and of its (tert-butyl)dimethylsilyl ether ((+)- 23 ) showed exciton-split type of Cotton effects attributed to through-space interactions between the s-gauche-buta-diene and s-cis-butadiene chromophores of these systems.