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Copper-catalyzed cascade synthesis of 2-aryl-3-cyanobenzofurans from o-hydroxybenzaldehydes and arylacetonitriles in the presence of copper acetate and sodium methoxide is reported. The synthesized 2-aryl-3-cyanobenzofurans emit bright blue under UV light with a quantum yield up to 88.9%.

A catalytic enantioselective Mannich-type reaction of a cyclohexanone-derived alkenyl trichloroacetate with isatin imines was achieved using an (S)-BINOL-derived chiral tin dibromide possessing a 4-tert-butylphenyl group at 3- and 3′-positions as the chiral precatalyst in the presence of sodium methoxide, sodium iodide, and methanol. Optically active 3-alkylated 3-amino-2-oxindoles having up to 90% enantiomeric excess were diastereoselectively obtained in high yields under the influence of the in situ generated chiral tin iodide methoxide.

A highly efficient and rapid method for the synthesis of 2-hydroxy-1,4-benzoxazine and butenolide derivatives has been developed. The key step in this protocol involves the reduction of benzoxazinone derivatives. Further reaction of 2-hydroxy-1,4-benzoxazine with secondary amines and sodium methoxide affords the corresponding 2-amino-1,4-benzoxazines and butenolide derivatives, respectively, in good yields.

A metal-free diastereoselective synthesis of novel 4-halo-3,6-di-aryl-2,6-diaza-bicyclo[3.2.0]heptan-7-one by intramolecular endo-trig haloamination of 3-amino-2-azetidinone is reported. The amidiolytic ring opening of diaza-bicyclo[3.2.0]heptan-7-one with sodium methoxide provides an easy access to previously unknown 4-halo-3-aryl amino-pyrrolidine-2-carboxylic acid methyl esters in good yields.

Nucleophilic ring opening of 23H-[21,23-didehydro-10,15,20-tris(4-methoxycarbonylphenyl)-5-oxaporphyrinato](trifluoroacetato)zinc(II) with various nucleophiles such as alkoxide, amine, thiolate, and enolate gave 19-substituted bilinone zinc complexes, and they were isolated as free base bilinones. An X-ray crystallographic study demonstrated that the product of 5-oxaporphyrin with sodium methoxide was 21H,23H-(4Z,9Z,15Z)-1,21-dihydro-19-methoxy-5,10,15-tris(4-methoxycarbonylphenyl)bilin-1-one with a helicoidal conformation. The structure of the product of 5-oxaporphyrin with an enolate of ethyl acetoacetate was 21H,22H,24H-(4Z,9Z,15Z,19E)-19-(1-ethoxycarbonyl-2-oxopropylidene)-5,10,15-tris(4-methoxycarbonylphenyl)-1,19,21,24-tetrahydrobilin-1-one, with three inner NH groups. The product with SH– was also the same tautomer, 21H,22H,24H-19-thioxo-bilin-1-one, with three NH groups, while the products with RO–, RNH2, and RS– nucleophiles were 21H,23H-bilin-1-ones with two inner NH groups. The first-order rate...

Bis-Boc-activated 2,5-diketopiperazines on reaction with potassium hydroxide or sodium methoxide in dry tetrahydrofuran led to Boc-protected hydantoins through an unprecedented ring contraction. This rearrangement was applied to several monosubstituted 2,5-diketopiperazines with good yields and regioselectivity.

During the total synthesis of calothrixin B, various novel and unexpected results were noticed such as cleavage of C–N bond in imine using sodium cyanoborohydride, sodium methoxide as a hydride source for reduction, deformylation in the presence of bromine, and deacylation using ceric ammonium nitrate (CAN). A detailed mechanism has been proposed for the unexpected results and a few of them are generalized. Temperature dependent NMR studies have been carried out for confirmation of the structure of one of the intermediates in the synthetic sequence.

A novel, inexpensive, and efficient palladium-, copper-, ligand-, and amine-free Sonogashira-type cross-coupling reaction of terminal alkynes with unreactive aryl fluorides in the presence of sodium, sodium methoxide, and calcium hydroxide under the assistance of a Grignard reagent was developed. A plausible mechanism was also suggested.

Heating of 6H-anthra[1,9-cd][1,2]oxazol-6-ones with dialkyl sulfoxides in sulfolane gave S,S-dialkyl-N-(9,10-dioxo-9,10-dihydroanthracen-1-yl)sulfoximides which underwent cyclization to naphtho-[1,2,3-cd]indol-6(2H)-one derivatives on heating in boiling tetrahydrofuran in the presence of sodium methoxide. p-Toluenesulfinic acid was isolated as by-product in the cyclization of S-methyl-S-(4-methylphenyl)-N-(9,10-dioxo-9,10-dihydroanthracen-1-yl)sulfoximide. The heterocyclizations of S,S-dipropyl- and S,S-dibutyl-N-(9,10-dioxo-9,10-dihydroanthracen-1-yl)sulfoximides to 1-ethyl- and 1-propylnaphtho[1,2,3-cd]-indol-6(2H)-ones were accompanied by formation of the corresponding 1-[1-hydroxyethyl(propyl)]naphtho-[1,2,3-cd]indol-6(2H)-ones.

Inexpensive formamide and sodium methoxide are employed for the N-formylation of amines and amino acids.

The ring transformation of dichloro β-lactams (I) in the presence of sodium methoxide is investigated.

The first catalytic system for amide bond formation is presented by using a mild, nontoxic, environmentally benign, and convenient synthetic protocol.

A facile and efficient synthesis of fully substituted pyridin-2(1H)-ones has been developed by the reaction of readily available α-oxoketene-S,S-acetals with malononitrile in the presence of sodium methoxide in methanol under reflux.

Borane (III) together with sodium methoxide is an appropriate donor for Suzuki-Miyaura type allenylation reactions.

Treatment of readily prepared lactam-fused benzothiazines (III) with a large excess of sodium methoxide in methanol unexpectedly gives indolo-1,4-benzothiazepines (V) instead of the expected 4,5-dihydro-1,4-benzothiazepines (VI).

A two-step sequence involving cleavage of β-lactams with sodium methoxide and subsequent cyclization of the resulting amino esters affords novel diastereomerically pure title compounds (IV).

O-benzyl protected pyranoid ene lactones (5,6-dihydro-2H-pyran-2-ones) were obtained in high yield in a two-step procedure. Treatment of a phenyl glycosyl sulfones , which were readily prepared from their corresponding sulfides, with lithium diisopropylamide (LDA) at −90 o C afforded elimination products . These intermediates were then treated with sodium methoxide in the presence of dicyclohexano-18-crown-6 .

The sodium salt of 4-amino-3-cyanopyrazolo[3,4-d]pyrimidine (1) was condensed with (2-acetoxyethoxy)methyl bromide (2) to provide the corresponding protected acyclic nucleoside, 4-amino-3-cyano-1-[(2-acetoxyethoxy)methyl]-pyrazolo[3,4-d]pyrimid ine (3). Treatment of 3 with sodium methoxide in methanol provided a good yield of methyl 4-amino-1-[(2-hydroxyethoxy)methyl]pyrazolo[3,4-d]pyrimidine-3- formimidate (4). Treatment of the imidate (4) with sodium hydrogen sulfide gave the thiocarboxamide derivative 5. Aqueous base transformed 4 into 4-amino-1-[(2-hydroxyethoxy)methyl]pyrazolo[3,4-d]pyrimidine-3- carboxamide (6) in good yield. Treatment of 5 with mercuric chloride furnished the toyocamycin analogue 7. Evaluation of compounds 1, 3-7 revealed that only the heterocycle (1) and the thiocarboxamide acyclic nucleoside (5) were active. Compound 5 was the more potent with activity against human cytomegalovirus and herpes simplex virus type 1.

If sodium methoxide was present as an electrolyte and nacleophile,the 1-acylpyridinium salt intermediate would be deacylated and converted to the free base pyridine.

The title compounds were synthesized in good yield by the reaction of dienes with primary aliphatic amines followed by treatment with sodium methoxide.

The formation of adducts with 1 :2 and 1:3 stoichiometry by methoxide addition to nitro-activated anisoles has been examined spectrophotometrically. For these equilibria the ‘basicity’ of sodium methoxide solutions in methanol is appreciably greater than that of corresponding potassium methoxide solutions. This is in contrast with other measures of basicity and is attributed to the association of the multi-charged adducts with cations which is stronger with sodium than with potassium ions.

Methyl 2-methoxy- and 2-tert-butoxycarbonylamino-2-deoxy-glycosides were obtained from methyl 2-carbamoyl-2-deoxyglycosides via Hofmann rearrangement with sodium methoxide/bromine/methanol or sodium hydroxide/sodium bromite/methanol or lead tetraacetate tert-butyl alcohol/dimethylformamide

Reaction of methyl bacteriopheophorbide d 2 in tetrahydrofuran with sodium methoxide led to oxidation of the ethyl side chain at position 12 to afford an acetyl group. Experiments with 18O2 suggest a mechanism via abstraction of a proton and reaction of the secondary radical formed with molecular oxygen. The implications of this mechanism for the biosynthesis of the bacteriochlorophylls are discussed. The 12-acetyl compound 3 was investigated by X-ray crystallography.

Rearrangements of the pyrimido[1,2-a]indoles 1 and 2 and the pyrimido[1,2-a]indolinium iodide 13 produce the 1,2,3,4,5,6-hexahydro-1,5-benzodiazocines 7–9. The diazepino[1,2-a]indole 16 produces the 2,3,4,5,6,7-hexahydro-1,6-benzodiazonine 18. Formation of compounds 7 and 8 is less facile than that of compounds 9 and 18. The pyrimido[1,2-a]indoles 1 and 2 and the diazepino[1,2-a]indole 16 undergo rearrangement with arenesulphonyl chlorides such as toluene-p-sulphonyl chloride but not with carboxylic acid chlorides to give the diazocines 10 and 12 and the diazonine 20. Mechanisms for the rearrangements are discussed in terms of indole 2,3-oxide intermediates. The reduction of the pyrimido[1,2-a]indole 2 with lithium tetrahydroaluminate generates the bicyclic aminal 26. The treatment of the bicyclic lactam 11 with lithium tetrahydroaluminate or with sodium methoxide results in ring-opening and formation of the 1,2,3,4-tetrahydro- and 1,2,3,4,5,6-hexahydro-1,5-benzodiazocines 27 and 28.

Reaction of methyl 2-bromo-2,3-dideoxy-5-O-(4-methylbenzoyl)-D-erythro-pentofuranoside (7)with silylated uracils using trimethylsilyl triflate as catalyst afforded the corresponding 2'-bromonucleosides(10). 2,3-Didehydro sugar was prepared by heating 7 with sodium azide in dimethylformamide. 2,2'-Anhydronucleosides were prepared by treating the nucleosides 10 with sodium methoxide at room temperature. 1-(2-Azido-2,3-dideoxy-β-D-threo-pentofuranosyl)thymine (15) and its α-anomer (16) were prepared by treating 10 with sodium azide and subsequently methanolic ammonia

Reaction of 2-chloroquinoxaline-3-carbonitril(1) with different types of nucleophiles such as thiourea, sodium methoxide, aniline, a-mercaptoacetic acid, ethyl-α-mercaptoacetate and anthranilic acid have been studied. Hydrolysis of 3-carbonitril-2(lH)-quinoxalinthione (11) with HCI gave 2(1H)-quinoxalinone-3-carboxamide (VIII). Compound I1 was reacted with bromoacetone, phenacylbromide and chloroacetonitrile in sodium ethoxide solution to yield thieno[2,3-b]quinoxaline derivatives IX, X, XI1 respectively. Compound X was reacted with ethylacetoacetate to give pyrido[5′,4′:4,5]thieno[2,3-b]quinoxaline-2-one(XI). Compound XI1 was reacted with ethylcyanoacetate to give 4-amino-3-cyano pyrido[4′,4′:4,5] thieno[2,3-b]quinoxaline-2-one(XVIII). Acylation of XI1 with Ac,O and benzoylchloride gave the monoacyl derivatives XI11 and XIV respectively. Hydrolysis of XI1 gave the corresponding carboxamide XIX. A number of pyrimido[5′,4′: 4,5]thieno[2,3-b]quinoxalines have been prepared by three other independen...

Dihydro-4,4-dimethyl-2,3-furandione (4e) was synthesized from diethyl oxalate, methylpropanal (1a) and formaldehyde in the presence of sodium methoxide. In a similar manner, analogs of dihydro-2,3-furandione 4 were prepared prepared using other aldehydes

Reactions of (E)-O-arylbenzaldoximes 1-3 with MeONa-MeOH have been studied kinetically. The reactions proceed via competing E2 and S N Ar reactions, in which the first step is rate-determining. Although the reactions were strongly influenced by the electronic effect of the β- and O-aryl substituents, they were insensitive to the steric effect of the O-aryl group, except that the S N Ar reaction was retarded by the CF 3 group of 2. For eliminations from 1-3 promoted by MeONa-MeOH, the k H /k D value increased and the Hammett p value decreased with better leaving groups

2,3-Dihalo-1-(phenylsulfonyl)-1-propenes, obtained by the addition of bromine or iodine onto (phenylsulfonyl)propadiene, were found to exhibit interesting reactivity as both mono- and dielectrophiles, with the mode of reactivity depending upon the nature of the nucleophile as well as the reaction conditions. Thus, amines or thiophenols smoothly effected substitution at the allylic site, while sodium methoxide reacted at the vinylic position through an addition-elimination process

5(4H)-Thiazolone derivative 4, obtained from N-dithiocarbobenzoxyglycine (1) and N,N-dimethyl-N′-heteroarylformamidines 3 in acetic anhydride, was rearranged with sodium methoxide in methanol followed by acidification with acetic acid into imidazole-4-carboxylic acid derivatives 5, 6 and 7. These were further converted with methyl iodide into methylthio derivatives 8, with hydrogen peroxide into the corresponding disulphide 9, with hydrazine and amines into hydrazide 10 and amides 11. In the reactions of 4a and 6a with amines in the presence of dichloromethane symetrically disubstituted methanes 14–18 were formed.

The reaction of methyl propionyl acetate with formamidine acetate in the presence of sodium methoxide produces 6-ethyl-4(3H)-pyrimidinone (1) in 67% isolated yield. Reaction with phosphorus oxychloride and subsequent catalytic hydrogenolysis affords 4-ethylpyrimidine (3) in 41% overall yield.

The 3'-iodonucleosides 4 have been synthesized by condensation of silylated 5-alkyluracils 2 with methyl 5-O-tert-butyldiphenylsilyl-2,3-dideoxy-3-iodo-D-threo-pentofur anoside (3). 4 was treated with sodium azide and the deprotected nucleoside 5 was subsequently obtained by treatment with tetrabutylammonium fluoride. The nucleoside 4 produced the corresponding 2',3'-didehydro-2',3'-dideoxy nucleoside 6 and 3',4'-didehydro-2',3'-dideoxy nucleoside 7 in elimination reactions on treatment with sodium methoxide.

Two new fluorescent regioselective O-acetylated N-acetylneuraminic acid (Neu5Ac) thioketosides, 2α-[4-(dansylamino)phenylthio]-7,8,9-tri-O-acetyl-N-acetylneuraminic acid {2α-[4-(dansylamino)phenylthio]-Neu5,7,8,9Ac4} (3) and 2α-[4-(dansylamino)phenylthio]-4-O-acetyl-N-acetylneuraminic acid {2α-[4-(dansylamino)phenylthio]-Neu4,5Ac2} (9) were synthesized. The synthesis of both derivatives started with the peracetylated benzyl ester 1 as precursor. The 7,8,9-tri-O-acetylated compound was prepared by partial deacetylation of 1 with sodium methoxide or with hydrazine hydrate, followed by catalytic benzyl ester hydrogenolysis. – Complete Zemplen deacetylation of 1 gave the Neu5Ac benzyl ester thioketoside 4, which was converted into the 8,9-isopropylidene-protected compound 5. By carefully performed regioselective 4-O-acetylation with acetic anhydride/pyridine in dichloromethane we obtained the desired fluorescent 4-O-acetyl derivative 6 and the nonfluorescent sulfonacetamide 7 as byproduct. Acidic 8,9-deprotection of 6 and finally catalytic hydrogenolysis of the benzyl ester 7 terminated this synthetic route, yielding 2α-[4-(dansylamino)phenylthio]-Neu4,5Ac2 (9). – The 4-O-acetylated derivative 9 could not be de-O-acetylated by influenza-C virus esterase. However, the virus esterase transformed the tri-O-acetylated derivative 3 in small amounts into the Neu5Ac thioketoside 10.

Treatment of methyl N-methylthionocarbamate (2a) with a catalytic amount of iodine or conc. H2SO4 results in the unexpected formation of the isomer, methyl N-methylthiolcarbamate (3a) in 90% yield. This has subsequently been transformed into methyl N-methylcarbamate (4a), by sodium methoxide. A curious transformation of methyl N-methyldithiocarbamate (1a) to (4a) on prolonged treatment with sodium methoxide is also discussed.

Treatment of dye 3 with sodium methoxide, morpholine, or diphenylphosphine gives the respective substituted derivatives 4, 5 and 6 in high yields. The reaction of 3 with sodium acetate followed by workup affords ketone 7 which is also obtained by demethylation of a methoxy derivative 4 under non-hydrolytic conditions.

Reaction of o-bromo aromatic amines (2, 4, 7, 10, 15) with ethyl potassium xanthate gave the corresponding fused thiazol-2(3H)-thiones (16, 19, 22) which in turn were first alkylated with methyl iodide and then treated with sodium methoxide to produce fused thiazol-2(3H)-ones (18, 21, 24). Treatment of 4-(4-pyridinyl)-benzenamine dihydrobromide (1) with DMSO gave 2-bromo-4-(4-pyridinyl)benzenamine (2). Reduction of 4-(4-bromo-3-nitrophenyl)-pyridine (3) with stannous chloride gave 2-bromo-5-(4-pyridinyl)-benzenamine (4)

The azabicyclic endo compound 3 was synthesized by reaction of enamine 1 with 2-benzoyl-1,3-dichloropropane (2). The thermodynamically more stable exo isomer 4 was obtained by epimerization of 3 with sodium methoxide. The reduction of 3 and 4 was carried out with different reducing agents. The syn/anti isomeric amino alcohols 7a/7b and 8a/8b were separated either by fractional crystallization of their fumarate salts or by column chromatography. The relative configurations at C-7 and C-9 and the conformations of the molecules were determined by chemical and/or NMR spectroscopic methods.

Reaction of N-cyanomethylisoquinolinium methiodide (2a) with sodium methoxide gave a rearranged tetrahydroisoquinolin-8-ol (5a) in high yield. With 1- or 4-substituted N-cyanomethylisoquinolinium (2b-d) and 8-hydroxy- tetrahydroisoquinolinium methiodides (2f), similar rearrangement was observed. PlausibIe mechanism on formation of the products was discussed

Stereoselective synthesis of α-D-glucosyl-branching polysaccharide by chemical and enzymic reactions was investigated. Ring-opening polymerization of 1,6-anhydro-3-O-benzoyl-2,4-di-O-benzyl-β-D-glucopyranose (1) with PF5 as catalyst at low temperature gave a highly stereoregular polymer, which was converted to 2,4-diO-benzyl-(1→6)-α-D-glucopyranan by debenzoylation with sodium methoxide. The polymer was glucosylated according to the glycosyl imidate method. Deprotection of the branched polysaccharide was carried out with sodium in liquid ammonia at -78 °C to give a (1→6)-α-D-glucopyranan having α-D-glucopyranosyl and β-D-glucopyranosyl branches. Only the β-D-glucopyranosyl branch of the polymer was completely removed by enzymatic hydrolysis by the use of cellulase to provide stereoregular (1→6)-α-D-glucopyranan having an α-D-glucopyranosyl branch at the C-3 position. Polymers were characterized by optical rotation, NMR spectroscopy, GPC, and X-ray diffractometry.

The cyclic carbophosphazene N 3 P 2 CCl 5 reacts with sodium methoxide, sodium trifluoroethoxide, and sodium phenoxide to yield the corresponding pentaalkoxy- and pentakis(aryloxy)cyclocarbophosphazenes. By contrast, N 3 P 2 CCl 5 does not react with the main group and transition metal nucleophiles lithium diphenylphosphide and lithium pentacarbonylmanganate and reacts incompletely with sodium dicarbonyl(η 5 -2,4-cyclopentadien-1-yl)ferrate

A convenient synthesis of enantiomerically pure aldopentono-1,4-thiolactones is described. Thus, 4-thio-D-ribono-1,4-lactone (12) has been prepared from D-gulono-1,4-lactone (1), via its 2,3-O-isopropylidene derivative 3. The 5,6-glycol system of 3 was oxidized with NaIO 4 . Chemoselective reduction of the resulting aldehyde function with NaBH 3 CN led to 2,3-O-isopropylidene-L-lyxono-1,4-lactone (7). Tosylation of 7 and subsequent treatment of the tosylate 8 with sodium methoxide afforded methyl C,5-epoxy-2,3-O-isopropylidene-L-lyxonate (9) as a key intermediate. Treatment of 9 with thiourea gave the C,5-thiirane derivative having the D-ribo configuration (10). Regioselective opening of the thiirane ring and simultaneous thiolactonization took place by heating 10 with KOAc-HOAc-DMF. The resulting 5-O-acetyl-2,3-O-isopropylidene-4-thio-D-ribono-1,4-lactone(11) was readily convertd, by acid removal (2% HCl) of the protecting groups, into the crystalline thiolactone 12. A similar approach was employed for the synthesis of 4-thio-L-lyxono-1,4-lactone(19), starting from D-ribono-1,4-lactone

Substituted cyclopropyl ether 3 is readily available from γ-bromoalkylidene malonate 2 via a Michael Induced Ring Closure (MIRC) reaction with sodium methoxide. Single Electron Transfer mechanism is suggested for the key cyclization step to account for the observed high reactivity of a tertiary halide, phosphonium salt and nitro compound.

Two methods for the chemoselective alcoholysis of acylureas were developed to generate esters and amides, respectively. In alcoholysis using sodium methoxide in methanol, methoxide attacked the acyl carbonyl to give the corresponding methyl ester. While in alcoholysis using lithium benzyloxide in diethyl ether, benzyloxide attacked the urea carbonyl to give the amide. The chemoselectivity originates in the different chelating abilities of the metals and the polarity of the solvents.

5-(2-Thienyl)-1-(2-deoxy-3,5-di-O-p-toluoyl-β-D-erythro-pentofuranosyl)-6-azauracil [VIII] and 5-cyclopropyl-1-(2-deoxy-3,5-di-O-p-toluoyl-β-D-erythro-pentofuranosyl)-6-azauracil [X] were obtained in high yields (93.5% and 81.3% respectively) exclusively as β anomers, by condensation of the corresponding silylated triazine bases with 2-deoxyu-3,5-di-O-p-toluoyl-D-erythro-pentosyl chloride in chloroform. After deblocking both nucleosides with sodium methoxide in methanol, 5-(2-thienyl)-6-aza-2′-deoxyuridine [IX] and 5-cyclopropyl-6-aza-2′-deoxyuridine [XI] were obtained. The nucleoside IX was further acetylated, brominated with Br2/CCl4 and deblocked with methanolic ammonia to give 6-aza-5[2-(5-bromothienyl)]-2′-deoxyuridine[XIV].

10-Chloroquinoxalino[2,3-c]cinnoline readily undergoes methoxydechlorination when treated with sodium methoxide. The 1-, 2-, 3-, 4- and 9-chloro isomers are unreactive towards this reagent, but the 9,10-dichloro derivative undergoes substitution of both chlorines (the 10-position being much the more reactive). The 9- and 10-bromo analogues are both unreactive towards sodium methoxide, but the 9- and 10-fluoro analogues are both highly reactive, to the extent that it has not been possible even to isolate the 10-fluoro compound. Routes to 9- and 10-piperidinoquinoxalino[2,3-c]cinnolines are described.

Regio- and stereoselective acetalizations of methyl α-D-lyxopyranoside (1), methyl β-L-arabinopyranoside (6), methyl α-D-galactopyranoside (11), and methyl β-D-galactopyranoside (13) with chloral, including an inversion of the configuration at C-3, were achieved with dicyclohexylcarbodiimide as a coagent. Additionally, the formed methyl 3,4-O-(2,2,2-trichloroethylidene)-α-D-arabinopyranoside 2, methyl 2,3-O-(2,2,2-trichloroethylidene)-β-L-lyxopyranoside 7, methyl 2,3-O-(2,2,2-trichloroethylidene)-α-D-gulopyranoside 12, and methyl 2,3-O-(2,2,2-trichloroethylidene)-β-D-gulopyranosides 14 and 15 contain an N-cyclohexylcarbamoyl group vicinal to the chloral acetal moiety; the compounds 12 and 15, moreover, a formyl group in 6-position. The formyl and carbamoyl functions may be cleaved stepwise with methanolic sodium methoxide. Deformylation of the 6-O-formyl derivative 15 affords the urethane 16 with simultaneous migration of the carbamoyl group from the 4- to the 6-position. The fluorination of 3 and 8 with anhydrous hydrogen fluoride/nitromethane/acetic anhydride, giving the glycosyl fluorides 4 and 9 without any cleavage of the cyclic chloral acetal functions, is described. BF3-catalyzed glycosylations of chloro-ethanol with the fluorides 4 and 9α/β yield the α-glycoside 5 and the anomeric mixture 10α/β, respectively, showing that neither a cyclic chloral acetal function in 3,4-O-nor in 2,3-O-position affects such reactions.

Methyl 2,3-dideoxy-3-fluoro-5-0-(4-phenylbenzoyl)-β-D-erythro-pentofuranoside was condensed with trimethylsilylated 5-substituted uracils to give nucleosides using trimethylsilyl trifluoromethanesulfonate as catalyst. In the case of 5-nitrouracil an acyclic nucleoside believed to be an intermediate for the corresponding nucleoside was isolated. The 5-substituents were selected from neural network calculations on compounds with potential activity against HIV-1. All compounds from the condensation reactions were deacylated by treatment with sodium methoxide in methanol